Ingineria · Authors: Amalia Ana DASCĂL, Tiberiu Nicolae MACARIE Publisher: PIM Iași Published:...

distr ibu ted with au totest m ag a zineVol. 8, no. 4 (33) / december 2014

SIAR IS A membeR of

InteRnAtIonAlfedeRAtIon ofAutomotIveenGIneeRInGSocIetIeS

euRopeAnAutomobIleenGIneeRScoopeRAtIon

Ingineriaautomobilului Society of

AutomotiveEngineers

of Romania

RomanianAutomobileRegister

Supported by

l Simulating the Performances of a Di Turbocharged Spark Ignition Engine l Analysis of the Depollution Mechanism on Diesel Engines l Numerical Model for NiTi Wires l Tuning Principles of Control and Protection Strategies for a S.I. Engine l Composite Indicators of Road Traffic Safety

Science and Management of Automotive and Transportation

SMAT 2014

METHODS AND WAYS OF DEPOLLUTION FOR THE AUTOMOBILE ENGINESAuthors: Florian IVAN, Daniel LIŢĂ, Andrei BUŞOI

Publisher: MATRIX ROMPublished: 2014ISBN: 978-606-25-0038-2

Despite the numerous restrictions imposed by the energy crisis of the fossil fuels and the more stringent emissions standards, the automobile still knows an impetuous develop-ment. However, the many beneficial social effects of the car must be examined in relation with the harmful effects caused by their exhaust emissions. The design of car engines today is facing with complex problems imposed by the development of „clean” engines. The concept of „green car” tends to become a reality.In this paper the authors provide an overview of theoretical and practical activities taking place to ensure a friendly interaction of the automobile engines with the environment. So, the following chapters are developed:o The interdependence Ecology-Pollutiono The pollutants produced by road vehicleso Formation mechanism of pollutantso Origin and formation mechanism of pollutants in the exhaust gas at spark-ignition engines. Influence of constructive, func-tional and technical factors. The influence of the nature of the fuelo Means of chemical depollution at the vehicles equipped with spark-ignition engineso Origin and formation mechanism of pollutants in the exhaust gas at compression ignition engine. The case of CIE with direct injection. Influence of constructive, functional and technical factors. The influence of the nature of the fuelo Means of chemical depollution at the vehicles equipped with CIEo Methods and equipment for measuring the concentration of chemical pollutants in the exhaust gas. Installations and test standsThe paper includes also an extensive bibliography.

BASIcS OF vEHIcLES ENGINEERING. THEORETIcAL AND APPLIED ELEMENTSAuthors: Amalia Ana DASCĂL, Tiberiu Nicolae MACARIE

Publisher: PIM IașiPublished: 2013ISBN: 978-606-560-350-9

The work is intended for students specializations Road Vehicles and Engineering Transportation and Traffic and anyone interested in construction, operation and maintenance of motor vehicles and the component elements.The book presents in a systematic approach a range of topics of study necessary to develop the theoretical and practical knowledge of the students regarding the general construction of motor vehicles, as well as the systems construction and their functional parameters: Structure, general arrangement and dimensions of road vehicles; Structure and arrangement of mechanic transmissions of road vehicles; Structure and arrangement of engines for road vehicles; Structure and arrangement of clutches for road vehicles; Structure and arrangement of manual gearboxes; Structure and arrangement of

automatically gearboxes; Structure and arrangement of CVT; Structure and arrangement of longitudinal transmission; Structure and arrangement of motor trains; Structure and arrangement of brake systems; Structure and arrangement of drive systems; Structure and arrangement of suspension for road vehicles; Structure and arrangement of rolling system.

3

Ingineria automobilului Vol. 8, no. 4 (33) / December 2014

Well Done, by Right People, Enthused by a Great ManLucru bine făcut, de oameni buni, animaţi de un om mare

Volkswagen is a giant of the automotive world – constituted as a rational and efficient platform of the marks Audi, Volkswagen, Seat, Skoda,

Bentley, Bugatti, Lamborghini, Porsche, MAN, Scania and Ducati.The group registered at the end of the past year 572 thousand of employees worldwide (as a comparison,

in the year 1972 the number of employees was 192 thousand). The global car sales in the year 2013 rendered 197 billion Euros. Every day, in the 107 Volkswagen factories – dispersed in 19 European and 8 Asian, American and African countries - 40 thousand automobiles are produced. Who is the man which leads such an empire? Some time ago, Dr. Ferdinand Piech, grandchild of Ferdinand Porsche – which created the automobiles and then the marks Porsche and Volkswagen – President of the Supervisory Board of the Volkswagen Group and his main owner has been nominated as a Honorary Professor at a relatively small University, in Zwickau. Despite hers size, this university has a strong Faculty for Automotive Engineering. At the other hand, the town Zwickau is the cradle of the AUDI Company. Ferdinand Piech speaks slowly, calculated, apparently cool, but his eyes reveal the passionate engineer and teacher. The innovation is at the origin of all the creation, the innovation is engine, the innovation is life, the eyes of the students absorb this life form through a magnetic way. The theoretical argumentation is excellent, the mentioned example is surprising as well as fascinating: Dr. Piech gives to the students an example of innovation, documented in many forms and underlined with numerous details. This example is focused on the eccentrically and genial sonny of the group – Ducati. The ingenious solutions adopted for the en-gine functions, the light and gracile profiles of the structures for resistance,

amortization and guidance and furthermore the elegance or the technical beauty of every part form in opinion of Dr. Piech innovation models for his engineers at Audi, Porsche and Volkswagen. Self-evident, it is very difficult to transfer an innovation from an exotic vehicle to a large series automobile, the conditions in terms of design and manufacturing are extremely differ-ent. But the potential between a well done work of a maestro and well done works of thousands of aspirants to a maestro state generate new innova-tions. At his age of 77 years, Ferdinand Piech spoke to the students during the first day of lectures six hours nonstop and during the second day 4 hours nonstop. On the platform in front of the University Amphitheatre were ex-posed during the two days of lectures the newest models of Bugatti, Bentley, Golf, Audi and Porsche. After the lectures he invited all students to visit the Volkswagen plant of Zwickau, visit guided by himself. Ferdinand Piech is directly implicated as an engineer in the conception, de-sign and manufacturing of every new automobile model of the group. He is often the first pilot of the prototypes.Ferdinand Piech suggests to the car makers respect and enthusiasm – as a good start platform for innovation. Dear professors, members of SIAR, I know and I appreciate many of you. We have not a bunch of famous marks, like Volkswagen, but we have many young lighting minds, we can suggest them respect and enthusiasm, as sane germinal of innovation. We have fertile fields waiting for seeds. I am confi-dent that we can make bunches from their fruits and flowers. Dear professors, please give as often as possible in this magazine examples of that what you can, from the scientific directions created by you, from your ex-periences, from your visions – for our students, doctors and young engineers.

Sincerely Yours, Prof. Dr. Ing. Habil. Dr. h. c. Cornel STAN

Summary „Ingineria automobilului“ No. 33 (vol. 8, no. 4)3 Well Done, by Right People, Enthused by a Great Man Lucru bine făcut, de oameni buni, animaţi de un om mare5 International Congress of the Society of Automotive Engineers of Romania – SIAR Science and Management of Automotive and Transportation Engineering – SMAT 2014 Congresul Internaţional al Societăţii Inginerilor de Automobile din România – SIAR 7 Simulating the Performances of a DI Turbocharged Spark Ignition Engine Obtained by Converting the Commercial K7M710 Engine. A Case Study Simularea performanţelor unui MAS supraalimentat, cu injecţie directă, obţinut prin conversia motorului de serie K7M710. Studiu de caz12 Analysis of the Depollution Mechanism on Diesel Engines Using the Systems NOxTRAP and HC-NOxTRAP Analiza mecanismului de depoluare a motoarelor diesel folosind

sistemele de tip NOxTRAP şi HC-NOxTRAP15 Numerical Model for NiTi Wires Designed as a Tool for Actuator Applications Model numeric pentru firele de NiTi, realizat ca instrument pentru aplicaţii din domeniul actuatorilor18 Tuning Principles of Control and Protection Strategies for a S.I. Engine Principii de calibrare a strategiilor de control şi protecţie pentru un motor cu aprindere prin scânteie22 Composite Indicators of Road Traffic Safety Indicatori compoziţi de siguranţă rutieră25 The National Contest for Students in Automotive Engineering „Professor Eng. CONSTANTIN GHIULAI”. Domain „Dynamics of Vehicles”. First Edition, 2014 Concursul Naţional Studenţesc de Inginerie a Autovehiculelor „Prof. univ. ing. CONSTANTIN GHIULAI” Domeniul „Dinamica autovehiculelor”. Ediţia I-a, 2014

4


romanian automobile

register

Director generalGeorge-Adrian DINCĂ

Director tehnicFlavius CÂMPEANU

Director adjunctDorin LEȚEA

auto test

Chief editorLorena BUHNICI

editorsRadu BUHĂNIţĂ

Emilia PETRE

Contact:Calea Griviţei 391 A,

sector 1, cod poştal 010719, Bucureşti, România

Tel/Fax: 021/202.70.17E-mail: [email protected]

www.rarom.rowww.autotestmagazin.ro

siar

ContactFaculty of Transport

University POLITEHNICAof Bucharest

Splaiul Independenţei 313Room JC 005

Cod poştal 060032, sector 6Bucureşti, România

Tel/Fax: 021/316.96.08E-mail: [email protected]

www.ingineria-automobilului.rowww.siar.ro

PRINTINGart grouP int srl

Str. Vulturilor 12-14, sector 3Bucureşti

Full or partial copying of text and pictures can be done only with Auto Test Magazine approval, of the Romanian Automobile

Register and of SIAR

soCietY oF automotiVe engineers oF romaniaPresident: Conf. dr. ing. adrian ClenCi, University of Piteşti

Honorary President: Prof. dr. ing. eugen negruŞ, University Politehnica of BucharestVice-president: Prof. dr. ing. Cristian anDreesCu, University Politehnica of Bucharest

Vice-president: Prof. dr. ing. nicolae burnete, Technical University of Cluj-NapocaVice-president: Prof. dr. ing. anghel CHiru, University „Transilvania” of Braşov

Vice-president: Prof. dr. ing. Victor oŢĂt, University of CraiovaVice-president: Prof. dr. ing. ioan tabaCu, University of Piteşti

General Secretary of SIAR: Prof. dr. ing. minu mitrea, Military Technical Academy of Bucharest

editor in chief: Prof. Dr. -Ing. habil. Prof. E. h. Dr. h.c. Cornel stan West Saxon University of Zwickau, Germany

executive editor: Prof. dr. ing. mircea oPrean, University Politehnica of BucharestDeputy chief editor:

Prof. dr. ing. gheorghe-alexandru RADu, University „Transilvania” of BraşovProf. dr. ing. ion CoPae, Military Technical Academy of Bucharest

Conf. dr. ing. Ştefan tabaCu, University of Piteştiredactors:

Conf. dr. ing. adrian saCHelarie, University „Gheorghe Asachi” of IaşiConf. dr. ing. ilie Dumitru, University of Craiova

S.l. dr. ing. Cristian ColDea, Technical University of Cluj-NapocaS.l. dr. ing. marius bĂŢĂuŞ, University Politehnica of Bucharest

S.l. dr. ing. george DRAgomir, University of Oradeaeditorial secretary: Prof. dr. ing. minu mitrea, General Secretary of SIAR

AVL List Romania – Werner moserRomanian Automobile Register – RAR – george-adrian DinCĂ

Renault Technologie Roumanie – sorin buŞeThe National Union of Road Hauliers from Romania – UNTRR – Florian miHuŢ

eDitorial boarD

HonoRArY CommiTTee oF siar

sCientiFiC anD aDVisorY eDitorial boarDProf. Dennis assanis

University of Michigan, Michigan, United States of America

Prof. rodica a. bĂrĂnesCuUniversity of IIlinois at Chicago College of

Engineering, United States of America

Prof. nicolae burneteUniversitatea Tehnică din Cluj-Napoca, România

Prof. giovanni CiPollaPolitecnico di Torino, Italy

Dr. Felice e. CorCioneEngines Institute, Naples, Italy

Prof. georges DesCombesConservatoire National des Arts et Metiers de Paris,

France

Prof. Cedomir DuboKAUniversity of Belgrade Serbia

Prof. Pedro estebanInstitute for Applied Automotive Research

Tarragona, Spain

Prof. radu gaiginsCHiUniversitatea Tehnică „Gh. Asachi” din Iaşi,

România

Prof. berthold grÜnWalDTechnical University of Darmstadt, Germany

Eng. eduard goloVatai-sCHmiDtSchaeffler AG & Co. KG Herzogenaurach, Germany

Prof. Peter KuCHarUniversity for Applied Sciences, Konstanz,Germany

Prof. mircea oPreanUniversitatea Politehnica din Bucureşti, România

Prof. nicolae V. orlanDeaRetired Professor, University of Michigan Ann Arbor, M.I., USA

Prof. Victor oȚĂtUniversitatea din Craiova, România

Prof. Pierre PoDeVinConservatoire National des Arts et Metiers de Paris, France

Prof. andreas seelingerInstitute of Mining and Metallurgical Machine, Engineering, Aachen, Germany

Prof. ulrich sPiCHerKalrsuhe University, Karlsruhe, Germany

Prof. Cornel stanWest Saxon University of Zwickau, Germany

Prof. Dinu taRAZaWayne State University, United States of America

Automotive Engineering: print edition publication, 2006 (ISSN 1842-4074), electronic edition, 2007 (ISSN 2284-5690).New Series of the Journal of Automotive Engineers (RIA), printed in 1990-2000 (ISSN 1222-5142)

5


Between 23rd and 25th of October 2014 the works of the annual SIAR Congress “SCIENCE AND MAN-AGEMENT OF AUTOMOTIVE AND TRANSPORTATION EN-GINEERING” - SMAT 2014, third edition, took place in Craiova. It was organized by the Faculty of Mechan-ics of the University of Craiova, De-partment of Automotive, Transpor-tation and Industrial Engineering with the support of FISITA (Inter-national Federation of Automotive Engineering Societies).Department of Automotive, Trans-portation and Industrial Engineer-ing of the Faculty of Mechanics from the University of Craiova hosted this event for the third time. The above-mentioned Department has always been considered one the centers of excellence within the field of the automotive engineering and transportation, broadly known both nationally and internationally.The Congress was accompanied by a wide range of activities that focused the attention of the Roma-nian and foreign specialists within the field of automotive engineering and transportation, attending the Congress works from Craiova. For a couple of days, Craiova became an international center of automotive engineering, thus offering the op-portunity for the participants to es-tablish or develop co-operation and information contacts with respect to the ongoing problems concerning

the automotive development, trans-portation safety and environment preservation.The active exchange in ideas and opinions, besides the researchers’ mobility, features the present society and yields in a developing engine of the automotive engineering branch of activity. With so numerous par-ticipants to the Congress, from the academic, social and economic en-vironments, both Romanian and foreigners, a favorable frame was created to successfully approach the main issues of the contemporary society that continuously generate challenges.The main topics of the SIAR - SMAT 2014 Congress provided an adequate scientific framework to an objective and intensive change of ideas and debates. Hence, the actual attention of the automotive engineering specialists has been driven to the following topics: Ad-vanced Propulsion Systems, Road Vehicles and Environment, Mod-ern Systems of Transportation and Traffic, Heavy and Special Vehicles, Advanced Methods in Engineering, Materials and Technologies.The about 200 participants to the Congress had the opportunity

to actively take part to the scien-tific debates of the scientific papers presented in the plenary session, section sessions, workshops, exhi-bitions, thematic visits and social events.The Congress works were wel-comed, during the opening ceremo-ny, by Dr.-Ing. Ludwig G.E. VOLL-RATH, vice-president of FISITA and president of EAEC (European Automotive Engineers Coopera-tion); Professor Dr.-Ing. Gunter HOHL, vice-president of the Aus-trian Society of Automotive Engi-neers - OVK Austria, ex-president of FISITA and ex-president of EAEC; Professor Dr.-Ing. Victor ILI ESCU, representing the Romanian Minis-

try of National Education; Profes-sor Dr.-Ing. Dan POPESCU - vice-rector for scientific research of the University of Craiova; Professor Dr.-Ing. Nicolae DUMITRU - Dean of the Faculty of Mechanics of the University of Craiova; Professor Dr.-Ing. Daniela TARNIţĂ - Director of the Research Center of Mechanical Engineering of the University of Craiova; Assoc. Professor Dr.-Ing. Adrian CLENCI - President of SIAR; Economist Ion PRIOTEA-SA - President of the County of Dolj Council; Mrs. Mihaela SAS - repre-sentative of ADV SV Oltenia, Mr. John OLDHAM - Plant Manager at Craiova FORD Engine Plant; Mr. Stefan KANYA - Regional Man-

Science and Management of Automotive and Transportation Engineering – SMAT 2014Congresul Internaţional al Societăţii Inginerilor de Automobile din România – SIAR International Congress of the Society of Automotive Engineers of Romania – SIAR

Professor Dr.-Ing.Minu MitreaSecretary General of SIAR

[email protected]

6


ager Europa SE AVL List GmbH; Mr. ION MIHAIU - Technical Manager of POPECI GRUP SA Craiova and Professor Dr.-Ing. Victor OţĂT - vice-president of SIAR and president of the SMAT 2014 Congress Orga-nizing Committee.After the opening ceremony, that takes place in the Blue Hall of the University of Craiova, the plenary session begins. Mr. John OLDHAM, describing the relevant directions of the automobile development in Ford Motor Co.’s vision for the near future, makes the first presentation.The second presentation belongs to Mr. Liviu POPESCU, Research Projects Manager at Renault Tech-nologie Roumanie. He approaches a very important topic for the pres-ent days - the electric vehicles. He also underlines the attention Re-nault Group pays to this topic.Mr. Gunther HOHL makes his pre-sentation and the public pays atten-tion to its topics since it concerns

“Developing the collaboration between the automotive engineers from Romania and other European countries”. The topic approached by Mr. Stefan KANYA from AVL Linz GmbH reveals the achieve-ments as well as the activities of the Austrian Company with respect to the vehicle’s integration in the en-vironment within the context of a continuously changing, interactive and communicational world.Eng. Adrian STROE presents the way CADWorks Craiova succeeded in developing themselves within the high competitive environment of automotive engineering software.The representative of CAELynx Craiova, Dr.-Ing. Stefan CASTRA-VETE promotes the determining role the integrated software solu-tion played in the success of the automotive engineering’s projects. Both his presentations focus on the original solutions developed by the Romanian specialists.

Eng. Oana ţÎRCOMNICU UNGA presents her point of view, underlining the need of correlation and coordina-tion of the automotive engineering de-veloping projects, sharing the exper-tise of INAS Craiova in this respect.The session works are presented in a special framework, both expressive and elegant, provided by the “Roma-nescu” University House throughout its halls: “Eminescu”, “Iorga”, “Roma-nescu”, “Green Hall” and “Red Hall”.The Congress works were also at-tended by university teachers, re-searchers and specialists of the Au-tomotive Engineering and Trans-portation domains from Austria, Bulgaria, France, Germany, Iraq, Israel, Macedonia, Republic of Moldavia, Pakistan, Serbia, USA, Hungary and RomaniaThe Congress provided framework to both presenting the achievements in the research work and in exchang-ing opinions on different topics. The Congress’s organizers provided a

technical visit to the FORD Roma-nia Motor Co. Also, 14 specialized companies presented their products within the exhibition organized in the University’s halls. There also were two workshops and the attendees debated automotive engineering spe-cific topics, software applications and complex automotive testing systems.Should also be mentioned that, while the Congress was developing its works, a student contest was also developing. We talk here about the national stage of the first edition of the “national contest for students in automotive engineering „Professor eng. Constantin Ghiulai” on „Au-tomotive Dynamics”. The students attending this stage of the contest previously won the local (univer-sity level) competitions. We could say that they strongly contributed to build up, among the congress at-tendees, an optimistic perspective with respect to the future of the Au-tomotive Engineering in Romania.

7


introDuCtionThe use of Spark Ignition Engines (SIE) in the automotive industry related to the more restrictive and difficult to attend pollution standards seams to become sus-tainable again in the period to come. This is possible because of the great increasing poten-tial given by the power density (kW/l), brake thermal efficiency (%) and lower specific emissions (g/kWh) of this type of engines. In case of Compression Ignition Engines (CIE) it is estimated that their rate of development are lim-ited first because their combus-tion characteristics and second because of the higher costs nec-essary to adapt the high-pressure

injection systems and the com-plex systems of the exhaust gases treatment.For SI engines, the new tech-nologies of fueling and stratified air-fuel mixtures formation by using in-cylinder gasoline direct injection, associated with the double low and high turbocharg-ing pressure, also with the de-crease of the engine displacement

Simulating the Performances of a DI Turbocharged Spark Ignition Engine Obtained by Converting the Commercial K7M710 Engine. A Case StudySimularea performanţelor unui MAS supraalimentat, cu injecţie directă, obţinut prin conversia motorului de serie K7M710. Studiu de caz

AbstrActThe use of the spark ignition engines for passenger cars under the more and more restrictive and difficult in reaching emissions legislation standards seams to become attractive for the next period. The new technologies of fueling and air-fuel mixtures formation as stratified charges by gasoline in-cylinder direct injection, associated with methods of down-sizing and down-speeding offer new perspectives to increase spark

ignition engines efficiency. The present work represents the beginning of a research pro-ject dedicated to the study of fueling DI spark ignition engines with different alterna-tive fuels. Engines characteristics have been obtained using a simulation model based on commercial Renault K7M710 engine. Keywords: spark ignition engine, turbo-charging, direct injection, simulation, efficiency, emissions.

andrei DÎrȚU

radu CHiriaC

alexandru raCOVitZĂ

„Politehnica” University of Bucharest, Splaiul Independenței 313, 060042 Bucharest [email protected]

Fig. 1. The schematic of the gasoline direct injection

Fig. 2. The heat release characteristic at full load and speed

8


(downsizing) together with the maximum torque speed (downspeeding) have materialized into a solution recently applicable by the engine designers.A significant number of stud-ies and research developed since 1960 [1-3] supports this method. Nowadays studies, exemplified as results [4,5], highlight that DI turbocharged SI engines allow

an obvious improvement of the low-speed torque as of the engine behavior at transient regimes. Combining the stratified mix-tures combustion at low speeds and loads, for which the relative air-fuel ratio is much leaner than 1 with the combustion of the homogenous mixtures at high speeds and loads characterized by relative air-fuel ratios more equal

to 1 requests a certain fuel injec-tion method inside the cylinder; the air-guided fuel injection, the wall-guided fuel injection, or the one directly orientated to the spark plug, all together related to a certain geometry of the sprayer nozzle [6-10].Impressive results speaking about the BSFC reduction up to 20% comparing to the classic indirect

multipoint injection are quoted [11,12]. Even more spectacular results seem to be offered by a new development concerning SI engines, referring to the gasoline direct injection and compression ignition (GDCI) [13], for which the efficiency values come close to those of diesel engine and NOx and particles emissions are far below the limitations of EURO V standards.The present work belongs to a large study proposed to be de-veloped by a team from the De-partment of Thermodynamics, Engines, Thermal and Refriger-ant Equipment, the Faculty of Mechanical Engineering and Me-chatronics from the University POLITEHNICA of Bucharest, related to the use of a SI direct injection engine, fueled with vari-ous alternative fuels. The study starts from an analysis based on simulation carried out to convert the commercial Renault K7M710 engine equipping the Logan 1.6 car vehicles into a direct injection engine. ComPutation moDelThe simulation study referring to the characteristics of the turbo-charging direct injection engine starts from the features of a Da-cia Logan 1.6 commercial engine (K7M710 type), normally aspi-rated, with a multipoint indirect injection: 4 cylinders in-line, 79.5 mm bore, 80.5 mm stroke, 9.5:1 compression ratio, 1595 cm3 total displacement, maximum power of 64 kW at 5500 rpm, maximum torque of 128 Nm at 3000 rpm. For the turbocharged engine, with direct gasoline injec-tion, the proposed model consid-ers another existing line-engine, Ford Escort RS 1.6 l Turbo [14], featuring: 96 kW rating power at 6000 rpm, 145 Nm rating torque at 4500 rpm, 4-in-line cylinders, 79.5 mm bore, 82.5 mm stroke, 9:1 compression ratio, 1597 cm3 total displacement. At this point, the authors do not propose a

Fig. 3.1. inlet valve lifting curve

Fig. 3.2. outlet valve lifting curve

9


discussion about the influences of the model on the knock phe-nomenon (see Fig.1 – the sche-matic of the gasoline direct injec-tion inside the SI engine cylinder [15])Modelling the processes from the turbo-compressor group implies the use of the AVL Boost v.2011.1 computer programs. The equa-tions refer to the conservation of the global energy exchanged from the inside to the outside of the cylinder and to the heat and mass flows through the inlet and out-let systems. At this point, a Vibe type relation has been proposed to describe the heat release from the cylinder (see fig.2) and a Woschni type formula (1990) to express the heat exchange. The mass transfer is given by the equations of sonic and subsonic flowing through the valves as by the injection characteristic im-posed to the gasoline injector. Figures 3.1 and 3.2 show the inlet and outlet valves lifting curves, based on the input data given by the valves timings and the geometric cams profiles. The schematic of the entire functional engine system re-sulted from the analysis of the all system parts and connecting elements is shown in fig.4. Fig-ure 5 highlights the chart of the turbo-compressor mass flow and its efficiency as functions of the turbocharging pressure at sev-eral revolution speeds. Choos-ing the running parameters for the turbo-compressor group has been discussed in-between three speeds regimes (44269 rpm, 55390 rpm and 66664 rpm), fi-nally the optimum values being decided for the lowest speed, cor-responding to 1.6 bar turbocharg-ing pressure. This pressure value is also revealed by the engine run-ning parameters, in fact by the air throttle percentage opening angle (71.4%) and by the engine speed, within the range from 2400 rpm to 6800 rpm. Fig. 5. setting the optimal parameters for the turbo-compressor group

Fig. 4. The aVl boost schematic of the direct injection turbocharged engine

10


obtaineD resultsThe simulation of both engines performances using the AVL Boost software package allows the direct comparison of the rat-ing power, rating torque, IMEP and BSFC for a range of speeds within 750 rpm and 5500 rpm. Figures 6 and 7 show the varia-tion of the effective power and the effective torque versus the en-gine speed. Comparing the values from these diagrams, a continu-ous increase could be noticed for the turbocharged engine for all the analyzed speed range, from 30% at 1000 rpm, to 48% at 3000 rpm and to 54% at 5500 rpm. At 5000 rpm, for the direct injection engine, the rated power was 97 kW, compared to 63 kW, which is the top value for the original engine. For the torque values diagrams, for the modified engine the maximum rated torque is 181 Nm at 3100 rpm, while in the case of the original K7M710 en-gine the corresponding top value is 128 Nm at 3000 rpm. In figure 8 there are plotted the in-cylinder pressure diagrams for both engines, at 5500 rpm and full load [16]. For the modified engine, the top pressure value is 81 bar and the IMEP is 15.4 bar, while in the case of the original engine, the maximum pressure is 67 bar and the IMEP is 10.6 bar. In terms of efficiency, as figure 9 highlights, BSFC values mark an increasing trend with the speed, within the maximum torque speed and maximum power speed, but in the case of the modified engine, the increasing slope is lower. It appears that the efficiency of the turbocharged engine is better than the effi-ciency of the initial engine at high speeds, marking a difference of 15% at 5500 rpm. Otherwise, the efficiency values are reversed at low speeds, the efficiency of the original engine being with 7% greater than the Fig. 7. rated torques vs. speed

Fig. 6. rated powers vs. speed

table 1. The turbocharging pressure vs. engine load and speed

Throttle angle (%)

turbocharghing pressure (bar)

speedrpm

11


one of the modified engine at 2750 rpm, close to the maximum torque speed. A possible explana-tion of this fact is that in the case of the direct injection engine run-ning at low speeds and loads the value of the relative air-fuel ratio hasn’t been corrected when using lean and stratified mixtures.ConClusionsThe simulation conducted study allowed to reveal the favorable trends to increase the performanc-es and the efficiency which are related to the conversion of the in-direct injection SI engines into in-cylinder direct injection engines.The obtained results highlighted a potential of 50% increase of maximum power, 40% increase of maximum torque and 15% decrease of BSFC when convert-ing the existing Renault K7M710 engine into a turbocharged direct injection engine, without any other eventual optimization.These results have to be correlat-ed and censored in relation with the limitations imposed by the specific gas emissions taken into consideration for the moment by the authors.

aKnoWleDgementsThe authors wish to thank AVL-Advanced Simulation Technologies for their con-stant support during the en-tire developed research.

rEFErENcEs[1] Conta, P., and Durbetaki, P., A Method Of Charge Stratification For Fo-ur-Stroke-Cycle Spark-Ignition Engines, SAE Technical Paper 580127, 1958, doi:10.4271/580127.[2] Hussmann, A., Kahoun, F., and Taylor, R., Charge Stratification by Fuel Injection into Swirling Air, SAE Technical Paper 630477, 1963, doi: 10.4271/630477.[3] Miyake, M., Okada, S., Kawahara, Y., Assai, K., A new stratified Charge Combus-tion System (MCP) for Reducing Exhaust Emissions Combustion Science and Te-chnology 1976, Vol. 12, pp. 29-46.[4] Kleeberg, H., Tomazic, D., Lang, O., and Habermann, K., Future Po-tential and Development Methods for High Output Turbocharged Di-rect Injected Gasoline Engines, SAE

Technical Paper 2006-01-0046, 2006, doi:10.4271/2006-01-0046.[5] Bandel, W., Fraidl, G., Kapus, P., Sikinger, H. et al., The Turbocharged GDI Engine: Boosted Synergies for High Fuel Economy Plus Ultra-low Emission, SAE Technical Paper 2006-01-1266, 2006, doi: 10.4271/2006-01-1266.[6] Kume, T., Iwamoto, Y., Iida, K., Murakami, M. et al., Combustion Con-trol Technologies for Direct Injection SI Engine, SAE Technical Paper 960600, 1996, doi: 10.4271/960600.[7] Fraidl, G., Piock, W., and Wirth, M., Gasoline Direct Injection: Actual Trends and Future Strategies for Injection and Combustion Systems, SAE Technical Pa-per 960465, 1996, doi: 10.4271/960465.[8] Stan, C., Guenther, S., Mar-torano, L., and Tarantino, C., As-pects of Mixture Formation and

Combustion in GDI Engines, SAE Tech-nical Paper 2000-01-0648, 2000, doi: 10.4271/2000-01-0648. [9] Sarikoc, F., Kettner, M., Velji, A., Spicher, U. et al., Potential of Reducing the NOX Emissions in a Spray Guided DI Gasoline Engine by Stratified Ex-haust Gas Recirculation (EGR), SAE Technical Paper 2006-01-1261, 2006, doi:10.4271/2006-01-1261.[10] Matsumura, E., Sugimoto, T., Kan-da, M., and Senda, J., Analysis of Fuel Flow and Spray Atomization in Slit Nozz-le for Direct Injection SI Gasoline Engines, SAE Technical Paper 2006-01-1000, 2006, doi:10.4271/2006-01-1000.[11] Takeda, K., Sugimoto, T., Tsu-chiya, T., Ogawa, M. et al., Slit Nozzle Injector for A New Concept of Direct Injection SI Gasoline Engine, SAE Tech-nical Paper 2000-01-1902, 2000, doi:

10.4271/2000-01-1902.[12] Schwarz, C., Schünemann, E., Durst, B., Fischer, J. et al., Potentials of the Spray-Guided BMW DI Combustion System, SAE Technical Paper 2006-01-1265, 2006, doi: 10.4271/2006-01-1265.[13] Sellnau, M., Sinnamon, J., Hoyer, K., and Husted, H., Full-Time Ga-soline Direct-Injection Compression Ignition (GDCI) for High Efficiency and Low NOx and PM, SAE Int. J. Engines 5(2):300-314, 2012, doi: 10.4271/2012-01-0384.[14] http://www.auto-data.net/ro/?f=showCar&car_id=7515[15] http:// autotehnic.files.wordpress.com/2013/08/injection_directe.jpg[16] Dârţu, A., Studiul performanţelor motorului K7M710, cu injecţie directă de combustibil, turbo-supraalimentat, UPB, 2014

Fig. 8. Pressures diagrams at 5500 rpm and full load

Fig. 9. bsFC values vs. speed

12


tHe motiVation analYsisThe air pollution has become a major social problem since the 60’s when was a significant increase of the urban population. Simultane-ously, the development of road transport has made it more difficult to maintain the air quality, espe-cially in urban areas. Reduction of environmental impact involved the apparition of standards to regulate the maximum permissible concen-trations of the main pollutants in the exhaust gases of spark ignition engines. Table 1 presents the evolu-tion of EU standards on maximum limits imposed of the pollution concentration emissions.In this context, experience has

shown that the particulate filter, DPF-(Diesel Particulate Filter), the oxidation catalytic converters, DOC - (Diesel Oxidation Catalyst) and the three-way catalytic con-verters, TWC - (Three Way Cata-lyst) are indispensable elements in the chain structure of the depollu-tion system specific light traction engines, but insufficient to comply with the EURO 6 limits. As a result, now are developed im-portant researches concerning the formation mechanism of the chem-ical emissions and their clean-up from the genesis and also the devel-opment of new after-treating sys-tems capable to reduce the concen-tration of nitrogen oxides (NOx), mechanical particles (PM) and un-burned hydrocarbons (HC).

Experience has shown that nitro-gen oxides are the most difficult to treat in the genesis. In the cylinder and the combustion chamber the nitrogen oxides are formed in con-ditions of high temperature and pressure in the presence of oxygen. In addition, the formation mecha-nism of NOx is interconnected with the formation mechanism of PM, so that the optimization researches are absolutely indispensable. In ad-dition, the compliance with pollu-tion limits required by law imposes an optimization research of the ex-haust gas post-treatment systems. Since diesel engines are operating with poor mixtures, reducing NOx, PM and HC using exhaust gas af-ter-treatment systems becomes an extremely complex task.

CHaRACteristiCs oF tHe Correlation betWeen tHe qualitY mixture anD nox anD Pm Formation meCHanism At high temperatures (greater than 2000 K), oxygen and nitrogen from air react forming nitrogen monox-ide, NO, a highly stable oxide that do not breaks down into N2 and O2 if the temperature falls. In the presence of oxygen can turn pro-gressively in NO2. Thus, under the generic name of nitrogen oxides is meant a mixture of NO and NO2 in varying proportions to the quality of the mixture and the operating mode of the engine.Experience has shown that the essential parameters which de-termine their formation are:

Analysis of the Depollution Mechanism on Diesel Engines Using the Systems NO xTRAP and HC-NO xTRAPAnaliza mecanismului de depoluare a motoarelor diesel folosind sistemele de tip NO xTRAP şi HC-NO xTRAP

AbstrActThe paper includes a detailed analysis of the functioning of modern depollution sys-tems on automotive engines, meant to realize the chemical retaining of the polluting emission like nitrogen oxides, called NOxTRAP or the simultaneous retaining of ni-trogen oxides and unburned hydrocarbons, called HC-NOxTRAP. In the first phase it is presented the motivation of the analysis starting from the evolution of European pol-lution standards and then are analyzed the correlations between the quality mixture and the formation mechanism of nitrogen oxides (NOx) and mechanical particles (PM) based on the Pischinger diagram. In the second part of the paper are analyzed the depollution mechanism phases of diesel engines using these systems: adsorption

phase and reduction phase, with the detailed presentation of the specific chemical reactions.It is also evidenced the way of managing the engine operation through the NOx sen-sor present in all the applications containing restraint systems of nitrogen oxides. It is concluded that the potential and the retention qualities of NOx, under the conditions of decreasing the concentration of PM and HC require the collaboration of these sys-tems with the engine, meaning important calibration research to ensure an optimum temperature regime and a quality mixture rigorously controlled.Keywords: nitrogen oxides, particulates, unburned hydrocarbons, NOxTRAP, HC-NOxTRAP

andrei BUȘOi

alina tUȚĂ

Florian iVaN

University of Piteşti, Str. Târgu din Vale nr. 1110040 Piteşti [email protected]

table 1. The evolution of euro standardsDI– direct injection II – indirect injection

13


temperature, oxygen concentration and the time reactions that occur during the formation mechanism of the nitrogen oxides, studied by Zeldovitch:O + N2 ↔ NO + N (1)N + O2 ↔ NO + O (2)N + OH ↔NO + H (3)In Figure 1, known as Pisch-inger diagram, is shown the in-fluence of the temperature and the excess air coefficient, λ, on the formation of PM and NOx. We can distinguish three areas: - zone 1, characterized by an ex-cess air ratio λ, close to 0.5 and the temperature of the burned gas from 1500 to 2500K. This qualifies the necessary condi-tions of the particles formation. - zone 2, represents the zone of the formation of nitrogen oxides and it is characterized by a poor mixture and a high combustion temperature.- zone 3 represents the oxidation of the particles, PM, due to high temperatures and the presence of oxygen in excess.At the end of the air compression in the cylinder the fuel injection takes place. It has very little time to va-porize and mix with air, about 10° RAC, this time represent the delay period in the auto ignition. There-fore, the mixture is very heteroge-neous and cannot be represented, depending on the temperature and λ , by a single point. The conditions of the mixture are represented by a number of points distributed along a yellow curve situated in the bot-tom of the Pischinger diagram. Gas temperature at the end of compres-sion is about 800K, except the rich mixture, the left side, which has a lower value due to the latent heat of vaporization. While the com-bustion process starts the value temperature increases and yellow curve moves to the upper bound of the diagram (red curve upper bound). The points characterized by a rich mixture, around the fuel jet will enter in zone 1 of the soot formation, (1500° K). At very high

temperatures, the soot becomes incandescent and forms the yel-low color of the flame. Thanks to the optimization of the mixture movement in the combustion chamber, the points characterized by a rich mixture are shifted to the right, zone 3 of oxidation, brings the removal of 98% of the particles formed. The yellow flame disap-pears, becoming again transpar-ent. The points characterized by a stoichiometric mixture afferent to the poor mixture will enter in zone 2 (2300° K ), the nitrogen oxides area formation. There are some points that do not form any soot or NOx. These points are character-ized by a very poor mixture. The diesel engine will form at the same time nitrogen oxides and particles. The major problem is the existence of the oxygen in the exhaust gases, and a catalyst cannot reduce NOx in an oxygenated environment. Therefore, the interposition of a storage element of the nitrogen ox-ides, called NOxTRAP, in the chain of the treatment of exhaust gas sys-tem become a necessity to ensure the compliance with the stringent limits imposed by the recent depol-lution standards (figure 4).analYsis oF tHe DePollution meCHanism on Diesel engines using noxtRAP anD HC-noxtRAPThe NOxTRAP system is consti-tuted by a catalytic reactor which is designed to store nitrogen oxide emissions. Functioning as a DOC ensures the regeneration tempera-ture in the context of cooperation with the particulate filter, and in addition, makes the function of storage/reduction of NOx. Its con-struction is similar to classical cata-lytic reactors, the major difference being that the active material con-tains barium or zirconium, in addi-tion to the noble metals (platinum, rhodium).The NOx-TRAP functioning in-volves two phases:- the adsorption phase occurs

during the normal engine opera-tion; in this phase, following the reaction with the platinum NO is converted to NO

2. It is demon-strated the fact that the degree of NO storage in the medium Pt/Ba/Al2O3 at 300 ° C without oxygen, is very low, increasing proportionally with the O 2 concentration. Also, the adsorption speed is 5 times higher for NO2, relative to NO and O2 [13, 15].Special roles during the storage phase have in equal measure the temperature and the amount of precious metals. Thus, for tempera-tures less than 300° C the oxidation of NO is limited. Regarding pre-cious metals, experience has shown an increasing amount of NOx stored in proportion to the concen-tration of Pt [7, 9], up to a thresh-old of 2 g/l of Pt. It is very impor-tant also the dispersion of the ac-tive elements on the surface of the catalytic converter: a significant

dispersion promotes the formation of platinum oxide, inactive for the oxidation of NO [14], while a low dispersion may limit the oxidation reactions [13].The NO2 molecules resulted in-teract with the barium oxide pro-ducing a compound, the barium nitrate, Ba (NO3)2, held on the surface of the monolith coated with the active material after the chemi-cal reaction below:2 NO+ O2 = 2 NO2 (4)BaO + 2NO2 + 1/2O2 = = Ba(NO3)2 (5)Experiments have demonstrated that the production of a NO mol-ecule per 3 molecules of NO2 consumed [6]. Because the NOx storing is realised progressively throughout the converter, it is probably that the NO resulting molecule is oxidized to at the exit in the atmosphere.- the reduction phase - is character-ized by the operation of the engine

Fig. 1. Pischinger diagram

Fig. 2. The functioning phases of the nox-tRAP system

Fig. 3. The nox sensor– functioning principle

14


close to λ = 1. It has been found that the operation of the engine in the two phases have to take place with a well-defined frequency; so the re-generation phase should be about 30 times less than that of the stor-age, this latter without exceeding 120 seconds. Reducing NO 2 stored with Barium is very difficult to achieve at low temperatures. For temperatures of 100-250o C the best reduction agent is hydrogen, H2, and temper-atures in excess of 250 ° C is carbon monoxide, CO, [12], [11], [13]. It was found that CO is the best reducing agent locally. This reacts progressively along the length of the monolith with the Pt elements and O2 adsorbent. Thus, the nitro-gen oxides, NOx, have the possibil-ity to spread rapidly in areas with

partial reduction reactions, result-ing substantial amounts of N2H. Regarding H2, it diffuses much fast-er and reacts preferentially with Pt. It has a slower effect on the nitrates reduction, but after the reaction will result only N2 molecules, [10]:Ba(NO3)2 + CO/HC/H2 → → CO2 + H2O + N2 (6)The two functioning phases are shown schematically in figure 2.The management of the engine operation is performed using the NOx sensor present in all the ap-plications containing restraint sys-tems of the nitrogen oxides. The schematic diagram is presented in Figure 3. The exhaust gases are all times tested, and the concentration of nitrogen oxides shows the stor-age capacity of the NOx-TRAP sys-tem. In the pumping cell 1st cavity,

the O2 concentration is established as reference for the stoichiomet-ric ratio, 14.7 kg air/1kg fuel. The oxygen percentage determines the pumping current whose value is proportional with the excess air coefficient. The flow of exhaust gas passes through the diffusion barrier and arrives in the measur-ing cell 2nd cavity, where, with the help of the reducing electrodes the nitrogen oxides are separated into O2 and N2. After these reac-tions arises a pumping current for oxygen that determines the NOx concentration.In Figure 4 are shown the compo-nents of a depollution system type NOx-TRAP and how it is disposed in the exhaust system architecture. It can be seen that for a maximum efficiency it is absolutely neces-sary an optimum cooperation of all elements, the computer injection motor, actuators and sensors, the depollution systems.One major problem on the NOx-TRAP system functioning is the fuel sulfur content. The sulfur ox-ides are retained like the nitrogen oxides in the adsorption phase and for the reducing phase it is neces-sary an operating mode of the en-gine with λ <1 and a temperature about 650 ° C.If a conventional NOx-TRAP is dedicated exclusively to reduce the nitrogen oxides, Nissan has de-veloped a new system called HC-NOx-TRAP, able to reduce both: NOx and HC (Figure 5).The working principle of this sys-tem is represented by the use of an additional layer capable to absorb the HC and to generate a chemi-cal reaction of reducing NOx even under operation condition with λ <1 (figure 6). NO is oxidized and retained in the form of NOx, at the same time with HC. In the reduc-tion phase, after the reaction of O2 with HC will result H2 and CO, which will determine an efficient reduction of NOx, as a result of the chemical interactions above mentioned.

ConClusionsThe depollution systems type NOxTRAP and HC-NOxTRAP are essential to ensure the compli-ance with the limits imposed by the EURO 6 emissions standards.To value the potential and reten-tion qualities of NOx and to de-crease the concentration of PM and HC, it is required an optimal collaboration of these depollu-tion systems with the engine, so, important researches to ensure an optimum temperature regime and a strict controlled quality of the mixture are made.

rEFErENcEs[1] Buşoi, C., Ivan, F. – Contribution to optimize the cooperation of C.I.E with the deppolution sistems using exhaust gsas recirculation, Congress Automotive – Motor- Mobility – Ambient, AMMA 2013, Cluj Napoca.[2] Buşoi, A., Ivan Fl., Dumitru, C., Experimental research concerning the validation of a FAP constructive vari-ant for a C.I.E. meant for light drive, Buletin Stiinţific Universitatea din Piteşti, 2010.[3] Buşoi, A., Ivan, F., Liţă, D. – Mo-dalităţi de depoluare a motoarelor diesel prin folosirea SCR, Revista Ingineria Automobilului nr.6, vol.6, 2012.[4] Buşoi, A., Contributii privind optimizarea unor procese si sisteme în vederea depoluării chimice a M.A.C.- urilor care echipează autoturismele de clasă medie, teza 2012[5] Cristea, D., Ivan, F., Serban, F., Economicitate si depoluare, Editura Universitatii Pitesti, 1995.[6] Cant, N.W. et al. Catal. Today 73 (2002) 271.[7] Hepburn, J.S. et al. SAE Techni-cal Papers Series N° 962051 (1996).[8] Ivan, F., Lită, D., Buşoi, A., Me-tode şi mijloace de depoluare ale motoarelor pentru automobile, Edi-tura Matrix, 2014[9] Kobayashi, T. et al. SAE Techni-cal Papers Series N° 970745 (1997).[10] Lesage, T. Thèse de Doctorat Université de Caen (2003).[11] Li, Y. et al. Topics Catal. 16/17 (2001) 139.[12] Mahzoul, H. et al. Topics Catal. 16/17 (2001) 293.[13] Mahzoul, H. et al. Appl. Catal. B 20 (1999) 47..[14] Olsson, L. et al. J. Catal. 210 (2002) 340.[15] Takahashi, N. et al. Catal. To-day 27 (1996) 63.[16] Tuţa, A., Trică, G., Ivan, F. – Preliminary experimental research regarding calibration strategy for com-pression ignition engine designed for passenger cars, Congress Automo-tive– Motor- Mobility – Ambient, AMMA 2013, Cluj Napoca

Fig. 4. The components of a nox-tRAP system

Fig. 5. The construction of HC-nox-tRAP

Fig. 6. The functioning phases of the HC-nox-tRAP system

15


introDuCtionShape memory alloys have unique properties which do not exist in many materials traditionally used in engineering applications. NiTi alloys are known as the most im-portant shape memory alloys (SMAs) because of their multi-tude of applications based on the shape memory effect (SME) and pseudo-elasticity (PE)[6], [8-9].Those properties are related to the martensite austenite (and reverse) transformation. This comes from the fact that NiTi alloys have supe-rior properties in ductility, fatigue, corrosion resistance, biocompat-ibility and recoverable strain [6]

[9]. When they are used as ac-tuators is it important to know the displacement vs. time at constant loading and the electrical energy vs. time. In order to save time and costs a numerical model is realized as an easy way to describe the func-tionality of SMA when the memory effect is electrical activated. Several researchers have already realized different models for SMA using the Joule principle that transforms electrical energy into heat. During this process the martensite structure is changing to austen-ite and the sample will execute a change of its shape. It is known from other models [1-3], [7], [11-18] that it is possible to fulfil the shape change when the sample is electrically activated. But in actua-tor industry this deformation is a function of time and stress. If the stress applied to the specimen is higher, then the phase change tem-peratures will linearly increase (see Fig. 1). This behaviour is the com-monly known stress dependency of the SME and has to be considered in each model.These two assumptions were the background for some numerical models. The models are divided in three groups: microscopic, meso-scopic and macroscopic. Each one considers the memory effect like a thermo-mechanical effect [1-3],

[7-18].Microcscopic [7]models study the atoms and the internal energy which is able to dislocate them. On the other side the macroscopic [1] models analyse the external dimen-sion using also the thermodynamic principles. In the actuator area, where one of the most important thing is the reduction of the assem-bly space, it there for makes sense to use one of the macroscopic models to find the best combina-tion (SME – space) [17]. The tech-nical applications take care of the thermo-mechanical aspects from SMA and also the space of assem-bly. These models are mesoscopic.

The last examples of such meso-scopic models are the Lexcellent and Lagoudas model8-9.Also, in the realm of the so-called non-equilibrium(or irreversible) thermodynamics, among others models [3], [7], [10-18] the pro-posed models based on the use of a set of thermo-mechanical equa-tions describing the kinetics of the martensitic transformations. The constitutive equations are developed in a non-linear man-ner on the basis of a free energy driving force and the laws of ther-modynamics. Boyd and Lagoudas [8] have extended the theory of the thermo-mechanical approach

Numerical Model for NiTi Wires Designed as a Tool for Actuator ApplicationsModel numeric pentru firele de NiTi, realizat ca instrument pentru aplicaţii din domeniul actuatorilor

AbstrActShape Memory Alloys (SMA)have unique properties which do not exist in many ma-terials traditionally used in engineering applications. Most important of these extraor-dinary characteristics are the pseudo-elasticity and the shape memory effect. This paper offers a new mathematical model for the shape memory effect when electrically activated. Many engineering applications start with the question concerning the required electrical energy, the prevent displacement and the needed space for the assembly. The behaviour of the NiTi-SMA actuator wirecan be mathematical described. Numerical simulations to

show qualitatively the ability of the model to capture the behavior of the shape memory alloys are also presented.The background of this paper is the development of a mathe-matical model which is able to give information about electrical tension, current intensity and deformation, when concrete values for diameter, length and/or mechanical tension of the SMA actuator wires are given. These information are very useful as an engineering tool in order to design actuator.Keywords: shape memory alloy, NiTi wires, mathematical model, numerical model, SMA model

Dr. ing.Viorel Gheorghiţă1,3

Dr. ing.Joachim Strittmatter1,2

Prof. dr. ing. anghel Chiru3

1 University of Applied Sciences Konstanz, Brauneggerstrasse 55, 78467 Konstanz Germany2WITg Institut für Werkstoffsystemtechnik Thurgau an der Hochschule Konstanz Konstanzer Strasse 19 8274 Tägerwilen Switzerland3„Transilvania” University of Braşov, Str. Politehnicii nr. 1, 500024 Braşov [email protected] Fig. 1. relation between temperature and stress [8]

16


by Ortin and Planes[12-13]and Raniecki and Lexcellent [9]in order to be valid for more general loading conditions such as non-proportional loading and combined isotropic and kinematic hardening[ 15]. The models are inconvenient for large-scale computations. The main rea-son is the difficulty in establishing the constant parameters. This aspect is very important and there for it is necessary for the model accuracy to determinate the constants for the SMA experimental. One way to de-terminate some constant parameters (phase change temperatures, elastic

module, heat coefficient, etc.) is us-ing the DSC device [19].These information are very impor-tant as an engineering tool in order to design an actuator. The focus of the numerical model presented in this work is related to the automotive safety system [5]. But this tool is also useful for other shape memory ac-tuators that find their applications in other fields, e.g. a thermally activated shape memory tube that represents the driving element in an intramed-ullary nail for bone lengthening [20].However the SMAs are character-ized by solid to solid displacive

transformation between the austen-ite and the martensite fraction, in re-sponse to mechanical loading, ther-mal loading and electrical loading.DesCriPtion oF tHe moDelThe current model starts from the Ortinand Planes approach. The issues are to determinate the elon-gation when SMAs are electrically activated and mechanically loaded.The background of this model is the first and second thermody-namic laws and also the Clausius – Duhem inequality [4].The model was divided in four

small systems:- Mechanical system;- Thermal system;- Hysteresis system;- Energy balance system.It can be written that the electrical energy should be equal with the output heat, as shown in the equa-tion 1.

(1)The next function should be math-ematically described:

(2) (3) (4)

Where:R - the electrical resistance of the NiTi wire;T –temperature value (can be As, Af, Ms or Mf);σ – mechniacal tension; ξ – martensite fraction.After solving the energy balance (considering mechanical energy, electrical energy and also heat loss-es) it can be designed in MathLab-Simulink a new numerical model for SMA, which is divided in the mentioned four small system mod-els: mechanical, hysteresis, thermal and energy balance.The main equation for structure changing is in connection with temperature.For the Martensite – Austenite changing the heating process will be determined according to equa-tion 5:

(5)Also for the Austenite-Martensite changing, the cooling process can be calculated according toequation6

(6)

Where:- As and Af are temperature points

Fig. 2. internal loops for the sma numerical model.

Fig. 3. martensite fraction vs.temperature at u=12V and a) i=3a, b) i=3.5a, c) i=4a, d) i=7a

A) B)

C) D)

17


for the austenite start and finish structure;- Ms and Mf the martensite start and finish temperature;- Tc – room temperature;- ξ – martensite fraction.The MathLab program is a close loop using equation 1 till 6 and is presented in the figure no. 2. First application is to see how much electrical energy is needed to ob-tain at least 4% elongation.The most important graphic for this simulation is the martensite fraction vs. temperature diagram. To record the real values for the electrical tension and current in-tensity, when the sample is loaded with 400N/mm2 and elongated at least 4% in 1s, actuator samples with 0.5mm diameter and active length 250mm were used.If the full martensite is 1, in fig-ure 3a, it can be observed that at a current value of 3A the structure doesn’t change in full austenite. The SMA is heated till 135°C, but is not full austenite. If the current inten-sity is increased till 4A the struc-ture changes into the full austenite. When the current value is greater than 4A the SMA is overheated and in the worst case damaged.resultsThe results from the model are compared with experimental test. For this comparison tests were performed with NiTi actuator wires between diameters of d=0.1-0.5mm. In the table 1 are presented the results for a mechanical tension of σ=250N/mm2; more tests at

different mechanical tension values were performed in the material test-ing laboratory. It can be observed that the calculated values of the numerical value fulfil very good in comparison to the measured values in most of the cases. The biggest dif-ference was found for the wire with 0.3mm diameter, where the elonga-tion value of the model differs 9.2% from the measured value. It has to be mentioned that the real tests were performed at different points in time and the room temperature was not recorded. This can be a reason for the slight differences of the measured and modelled values, as the model is referring to a room temperature of 20°C in this case. In spite of these slight differences it can be stated, that in the actuator field this model is very useful5.ConClusionThe results prove that the NiTi wires are able to be activated using elec-trical energy in order to show the desired function. This activation can be described with a numerical model that only shows little differ-ences in comparison to the meas-ured values obtained in real tests. For the next future more real tests have to be carried out at precise conditions (e.g. recording the room temperature) and the model has to be slightly modified with some additional parameters in order to minimize the differences of the cal-culated values. This model is very useful for engineering applications in order to design a device with NiTi actuators.

In the automotive industry the electrical energy is limited, but the actuators require a specific energy. Before starting the design of a new actuator for this industrial field, the presented model can be very useful to define the SMA wires, e.g.: num-ber, diameter and length of wires.

aCKnoWleDgement- Gratitude is given to the HTWG Konstanz for the financial support in order to realize this work within the framework of a “Small Research Project”.

rEFErENcEs[1] F. Auricchio, Shape memory al-loys: applications, micromechanics, macromodeling and numerical simula-tions, Ph.D. Dissertation, University of California at Berkeley, Berkeley, CA, USA, 1995[2] J.C. Boyd, D.C. Lagoudas, A ther-momechanical constitutive model for shape memory materials. Part I. The monolithic shape memory alloy, Int. J. Plasticity 12, 805, 1996[3] L.C. Brinson, M.S. Huang, Simplifications and comparisons of shape memory alloy constitutive models, J. Intell. Matl.Syst. &Struct., 7 108, 1996[4] M. Fremond, The clausius-Duhem inequality - an Interesting and Productive Inequality, Advance in Mechanics and Mathematics, 12, 107-118, 2006[5] V. Gheorghita, P. Gümpel,J.Strittmatter, A.Chiru,T. Heitzand M. Senn, Using Shape Memory Alloys in au-tomotive safety systems, Proceedings of the FISITA 2012 World Automotive Congres, Lecture Notes in Electrical Engineering Volume 195, 909-917, 2013[6] P. Gümpel, Formgedächtnis-legierungen – Einsatzmöglichkeiten in Maschinenbau, Medizintechnik und Aktuatorik, Expert-Verlag, Renningen, 156 p., 2004[7] A. Kelly, K. Bhattacharya, R.M. Murray, A constitutive Relation of Shape Memory Alloys, California Institut of Technology, 180 p., 2009[8] D.C. Lagoudas, Shape Memory Alloys–Modeling and Engineering Applications, New York, Springer, 350p, 2008[9] C. Lexcellent, Shape memory Alloys Handbook, Wiley, London, 390 p., 2013[10] C. Liang, C.A. Rogers, One-dimensional thermomechanical constitutive relations for shape memory materials, J. Intell. Mater.SystemsStruct. 1, 207, 1990[11] H. Maier and A. Czechowicz,

Computer-Aided Development and Simulation for Shape Memory Actuators, Metallurgical and Materials Transaction, VOL 43A, 2882-2890, 2012[12] J. Ortin, A. Planas, Thermodynamic analysis of thermal measurements in ther-moelastic martensitic transformations, Acta Metall. Mater.36, 1873, 1988[13] J. Ortin, A. Planas, Thermodynamics of thermoelastic mar-tensitic transformations, Acta Metall. Mater. 37, 143, 1989[14] K. Otsuka, and C.M. Wayman, Shape Memory Materials, Press Syndicate of the University of Cambridge, Cambridge, 2002[15] V.P. Panoskaltsis, S. Bahuguna, D. Soldatos, On the thermomechani-calmodeling of shape memory alloys, International Journal of Non-Linear Mechanics 39, 709-722, 2004[16] B. Raniecki, C. Lexcellent, RL-models of pseudoelasticity and their speci-fication for some shape memory solids, Eur. J. Mech. A 13, 21, 1994[17] F. Schiedeck, Entwicklung eines Modells für Formgedächtnisaktoren im geregelten dynamischen Betrieb. PhD, Leibniz, 150 p., 2009[18] K. Tanaka and R. Iwasaki, A phe-nomenological theory oftransformation superelasticity, Eng. Fract.Mech. 21, 709, 1985[19] G. Laino, R. De Santis, A. Gloria, T. Russo, D. S. Quintanilla, A. Laino, R. Martina, L. Nicolais and L. Ambrosio, Calorimetric and Thermomechanical Properties of Titanium-Based Orthodontic Wires: DSC–DMA Relationship to Predict the Elastic Modulus, Journal of Bimaterials Applications, 26, 829-844, 2012[20] T. M. Boes, P. Guempel, R. Storz Irionand J. Strittmatter, Implantatvorrichtung zur Gewebe-und/oder Knochendistrak- tion sowie Verfahren zum Betreiben einer solchen, Patent no. EP2173267B1, February 2009

table 1. Comparison between measured and model results

18


introDuCtionThe influence of internal combus-tion engines over the environment is a well known problem in today’s society and motivates the develop-ment of more efficient and cleaner engines. For these engines to meet future legislation regarding toxic emissions is necessary to use more advanced concepts of engine con-trol and combustion.These concepts benefits significant-ly from the improved control of the combustion using the dosage of the closed loop and adaptive systems for the injection times, in contrast

to conventional systems of pre-calibration for the open loop con-trol of the combustion. However, any closed-loop control system is based on the right information received from the various sensor configurations regarding the com-bustion process. All of the sensors conteins devices located in the cylinder, like the cylinder pressure sensor or the ionic current, on the cylinder block, on the cam shaft or on the crank shaft. These sensors allow monitoring the combus-tion process while getting all the information needed to develop a

strategy for estimating torque.The engine torque estimation has been an active area of research in the last decade, primarily in terms of electronic control units that be-came present on modern vehicles to optimize engine performance while at the same time, emissions.[1] The estimation of the engine’s torque is also needed to elaborate protection strategies for gear-boxes and other components of the transmission. Obviously, the performance of a engine control system depends on the accuracy

Tuning Principles of Control and Protection Strategies for a S.I. EnginePrincipii de calibrare a strategiilor de control şi protecţie pentru un motor cu aprindere prin scânteie

AbstrActEngine effective torque is not only a preformance parameter but also a control pa-rameter. Calibration of the developed torque of a s.i. engine requires a strategy and cartograms assemblies that allow the computer software to estimate the value of this injection parameter. Estimation is done by interpreting several engine operating pa-rameters: the spark advance, enrichment, intake air flow, engine speed. Knowing the torque available for any speed and load allows inter-system exchanges between the engine electronic control unit and other control units of vehicle and possible use of

security surveillance strategies for the powertrain.The achievement of an accurate estimation for the engine torque can influence and develop multiple areas: engine diagnostics, engine control starting from the developed torque, traction control and vehicle dynamic control.The paper contains a description of a calibration principle for estimating the engine torque and its use in the development of control and protection strategies.Keywords: Estimate torque, S.I. engine, filling efficiency, enrichment efficiency, spark advance efficiency

George Marian triCĂ

alina tUȚĂ

Florian iVaN

University of Pitești, Str. Târgu din Vale nr. 1 110040 Pitesti [email protected]

Fig. 1. The set of sensors and actuators used to control the throttle.

19


of the model used for estimation of the engine torque.tHe eleCtroniC Control oF tHe intaKe tHroTTle anD suPerCHarging in tHe Context oF torque estimation as a CalibRAtion stRAtegY.Electronic Throttle Control (ETC) develops from conventional me-chanical drive systems using levers and cables to control the throttle position. The electronic control uses an electronic control unit, an electric motor for changing the angle of the intake throttle and an angular position sensor to know the actual throttle opening. Thus the system is able to control the throttle position consistent with multiple functional parameters and can also take some functions such as reducing engine torque for electronic traction control (ASR) or automatic transmission.In figure 1 the following symbols were used:R.A.S. – Intercooler;W.G. – Waste gate;Mono 1 – Monolith 1;

Mono 2 – Monolith 2;E.C.U. – Electronic control unit;1 – throttle position sensor;2 – engine speed sensor;3 – intake temperature sensor;

4 – intake absolute pressure sensor;The driver presses the accelera-tor pedal and its position is read and transmitted to the electronic

control unit from the position sensor (1). Together with sig-nals from temperature sensors, pressure, speed, throttle posi-tion realised a request of engine torque. The required torque will be obtained by modifying spark advance and by controling the en-gine inlet air flow, the latter being controlled by adjusting the the in-take throttle angle or changing the boost pressure.After calculating the airflow re-quired to obtain the engine torque, the electronic control unit changes the throttle position having, in the same time, an information from its body-mounted sensor. Similarly, the boost pressure is controlled by modifying the waste-gate posi-tion.[2][3]Modern spark ignition engines have a ECU controlled discharge valve to divert the boost pressure in front of the compressor when the intake throttle is closed.tHe CalibRAtion PrinCiPle oF engine torque estimation For a s.i. engine.

Fig. 2. Determination of the indicated engine torque starting from s.i. advance. [4]

Fig. 3. The influence of richness over the indicated engine torque. [4]

20


The calibration of the developed engine’s torque involves an as-sembly of adjustments and labels which allow the software from the electronic control unit (E.C.U.) to estimate the value of this parame-ter. The torque estimation is done by interpreting multiple operat-ing parameters of the engine: the spark ignition advance, richness of the mixture, engine air flow rate and engine speed. In the analyti-cal way the torque estimated value can be written:

= ∙ ∙ ∙ + (1)Where:

eestM -effective engine torque,

estimated by the E.C.U. software based on the values of the others

engine parameters: sη , R

η and uη .

maxiM -maximum indicated en-gine torque, developed at a con-stant speed and charge.

sη -spark advance efficiency, can

be written as:

= (2)

The notations of equation number 2 represents the:

aplα -applied s.i. advance for which we obtain the applied en-gine torque

á_aplM (calculated

based on the advance parabola and

aplα for 1=R , .ct

u=η ,

and .ctn = .).

optα -optimal s.i. advance for which we obtain the maximum

engine torque á_opt

M (retained in the cartogram for 1=R

.ctu=η , and .ctn = ).

– the mixture richness ef-ficiency is expressed by the equation:

= (3)Where:

aplR -applied richness;

optR -the richness for which the

engine develop the maximum torque. In figure 3 we can see the

Rη de-

termined keeping constant the val-ues of sá ,

uη and n.

uη -engine filling efficiency, it can

be written as= (4)

Equation 4 uses the following notations:

aplu -represents the actual engine filling, or requested by driver, ob-tained by changing the position of the intake throttle;

maxu -maximum engine filling in standard conditions (temperature 25⁰C and pressure 1013 mbar). For naturally aspirated engines the filling efficiency is

uη = 0.96

due to gas-dynamic losses through air intake.

PPM -represent the torque loss-

es, which are calculated by the sum

of the mechanical losses, pumping losses and auxiliary losses due to accessories.In equation 1 is observed that changing the filling efficiency and keeping the other parameters con-stant determines the modification of estimated or required engine torque. In figure 4 there is a trans-position of equation 1.ProteCtion anD surVeillanCe stRAtegies For a s.i. engineThe use of electronic control units and various engine control software has enabled the diagno-sis of engine components or the protection against certain physi-cal processes that can occur dur-ing operation.Protection strategies performs automatic modification of certain engine parameters to lower or control certain harmful physics engine. An example of a protec-tion strategy is represented by the detection and reduction of knock occurred during the engine run-ning. The detonation, as a abnor-mal phenomenon of air-fuel mix-ture combustion, has a number of negative effects starting with dis-turbing engine noise to the piston and cylinder head damage.To control and eliminate detona-tion the control strategy is based on information received from the knock sensor, piezo-electric sensor mounted on the cylinder block, and retreat the spark ad-vance according to the informa-tion received from it.[6] Figure 5 renders the operation zones of this strategy depending on load and speed for a turbocharged engine.There are three areas:• area without detection which is the part of the engine field where the strategy is inhibited to elimi-nate the occurrence of false de-tections and unnecessary retreat of the spark advance.• average detection area, where the strategy should eliminate the

Fig. 5. anti knock strategy on the engine field.[5]

Fig. 4. schematic diagram of engine torque realization and estimation. [5]

21


detonation (noise considerations only). In this area it is preferred to have the non-detection because engine knock is not dangerous.• critical area of detonation, in this area the detonation are very strong and there is an increased risk of engine damage.Surveillance strategies provides a continuous comparison be-tween the real values of engine parameters measured by sensors or ECU estimated from the infor-mation received from them, and the values modeled or mapped in the initial stage of calibration. Surveillance strategies can target either a single parameter or en-tire engine assembly . An exam-ple of a component surveillance can be continuous diagnostics of pressure in the intake manifold. Figure 6 presents the operation of a full diagnostic pressure in the intake manifold. Relative er-ror between the actual pressure measured by the pressure sensor and the modeled one by the ECU is compared with two calibrated thresholds. If the error exceeds one of the thresholds then it will be considered that there is a prob-lem on the intake inlet and en-gine performance will be limited automatically.As regards the whole diagnostic engine, a strategy can be designed based on the estimation and reali-zation of the engine torque shown in the previous chapter. It realizes the difference between a torque mapped, depending on load and engine speed, and torque esti-mated based on information from sensors and actuators. This error is compared with two thresholds previously calibrated according to the results, it is decided if the engine goes into a safe mode to limit potential damage.ConClusionsIncreasing computing capacity electronic control units allow the use of engine control software and thus the emergence of strate-gies and methods for calibration.

At present some strategies are used to simulate and predict vari-ous engine sensors so it is pos-sible their physical elimination, reducing production costs and increasing profits. Engine calibra-tion offer a multitude of possi-bilities in terms of engine control and the use of new technologies.The large number of parameters managed by the ECU increases drastically the time needed for calibration and requires the use of mathematical models to simu-late the engine and obtain a tun-ing correlated with a reduction in costs.Engine calibration activity is an absolute necessity to develop vehicles that meet the limits im-posed by the active pollution

without compromising dynamic performance and consumption. In this context’s calibration start-ing from torque estimation is a complex activity.Related calibration strategies tar-gets at the same time to avoid the phenomenon of detonating com-bustion, supervision and protec-tion of the motor.For calibration of spark ignition engines for light cars, I appreci-ate that it requires the develop-ment of specific methodologies to ensure research shortening repercussions in terms of reduc-ing costs without compromising dynamic performance, economi-cal and ecological requirements of legislation in the context of higher competition.

Fig. 6. The relative error function of time of the pressure in the intake manifold.[5]

rEFErENcEs[1] A. Rakotomamonjy, R. Le Riche, D. Gualandris, and Z. Harchaoui, A comparison of statis-tical learning approaches for engine torque estimation, Control Eng. Pract., vol. 16, pp. 43–55, 2008.[2] A. Y. Karnik, J. H. Buckland, and J. S. Freudenberg, Electronic throttle and wastegate control for turbochar-ged gasoline engines, Proc. 2005, Am. Control Conf. 2005., 2005.[3] P. Moulin and J. Chauvin, Modeling and control of the air system of a turbocharged gasoline engine, Control Eng. Pract., vol. 19, pp. 287–297, 2011.[4] G. Trică, A. Tuţă, and F. Ivan, Development of a calibration strategy for a S . I . engine starting from the es-timation of the engine torque, AMMA 2013, Cluj Napoca, 2013.[5] G. Trică, Principii ale calibrării motoarelor cu aprindere prin scânteie, Ref. Cercet., vol. 1, 2014.[6] X. Zhen, Y. Wang, S. Xu, Y. Zhu, C. Tao, T. Xu, and M. Song, The engine knock analysis - An overview, Applied Energy, vol. 92. pp. 628–636, 2012.

-40

10

60

110

160

210

260

310

360

200

250

300

350

400

450

500

550

600

650

700

0 10 20 30 40 50

Rela

tive

erro

r [m

bar]

Inle

t pre

ssur

e [m

bar]

Time [s]The pressure measured by a sensor Modelised pressure Relative error

Minimum threshold Maximum threshold

Fig. 7. Functioning diagnosis of the whole engine starting from the torque estimation.[5]

22


1. introDuCtionEvery year, at a worldwide level, more than 1.2 million people lose their lives in road traffic accidents, and the material damage costs and other human consequences (serious or mild injury of other people) recorded as a consequence of these road events, rising to the amount of hundreds of millions of Euros[1].In 2013, Romania registered 92 people deceased (as victims from road accidents) per million of inhabitants (Fig. 1), the direction in recent years of this index being a decreasing one. In spite of this, at the end of 2013, Romania has exceeded the average recorded for the EU level (52 people deceased per million of inhabitants), and countries such as Luxembourg (87 people deceased per million of inhabitants), Bulgaria (86 people deceased per million of inhabitants), Latvia (86 people deceased per million of inhabitants), Lithuania (85 people deceased per

million of inhabitants), etc.The Romanian road environment has formed the subject of the work of many researchers who have characterized it, where appropriate, such as possessing varying degrees of objectivity. A group of researchers, however, reporting on the road phenomenon in Romania, concluded that, in our country, the public action of traffic safety appears neither well structured nor well orchestrated [3].2. PerFormanCe inDiCators in tHe Domain oF roaD tRAFFiC saFetYMonitoring the progress of road traffic safety and the measures implemented in order to improve it, generally requires the use of indicators which would allow the evaluation of security conditions of a road traffic system. Often, in this regard, indicators are employed that refer to the number of road traffic accidents, the deceased people, as a result of their involvement in such events, people seriously injured or mildly injured, except for the fact that the number of accidents and deaths does not reveal the processes that led to their occurrence. Therefore, additional indicators for road traffic safety are required which would enable a possible complex analysis of the entire phenomenon on accidents [4].Performance indicators from the domain of road traffic safety (SPIs – Safety Performance Indicators) are defined as being the measures

which reflect the conditions of exploitation of a road traffic system and which influence the security performance of the system [5] and [6].These were developed in the SafetyNet project initiated by the European forums, according to the model acknowledged in the reference literature under the title of „the Sunflower“ (Fig. 2), on seven sub-areas of road traffic safety: the use of alcohol and drugs, speed, protective systems, the use of daylight illumination, the passive safety of vehicles, trauma management and road ways (roads).Regarding the role of performance indicators, some researchers claim that these can safely perform an active monitoring function or a reactive monitoring function. The first means identifying and reporting incidents, thus facilitating the process of learning

from mistakes, while the second function provides feedback regarding the performance before an incident or accident occur. Indicators with the role of reactive monitoring show when a desired safety result has failed or it has not been achieved [8].3. ComPosite inDiCators oF roaD tRAFFiC saFetY3.1. necessity and definitionThe necessity for some composite indices of road safety (CRSPI – Composite Road Safety Performance Index), which can describe all relevant aspects in a concise and comprehensive manner, is justified primarily through the need of drawing certain comparisons regarding the results obtained by some countries, the main purpose of this type of international cooperation being that of learning from others. Secondly, it has been observed that there is a necessity to reduce

Composite Indicators of Road Traffic SafetyIndicatori compoziţi de siguranţă rutieră

todiriţă-ionuţ DUMBraVĂ

radu GaiGiNSCHi

adrian SaCHeLarie

„Gheorghe Asachi” Technical University of IaşiBdul Professor Dimitrie Mangeron nr. 43 700050 Iaşi [email protected]

AbstrActThe modern world aims to ensure traffic on public roads under safe conditions. Thus, monitoring the progress of traffic safety and the measures taken in order to improve it generally requires the use of certain indicators which would allow the evaluation of safety conditions of a traffic system. Taking into consideration that the traffic safety management in Romania may be significantly improved, the application of certain

composite indicators, in the case of our country, becomes appropriate or the implemen-tation of modern statistics, summaries, that can capture, indeed, the reality and deter-mine the arousing interest of the general public and, therefore, the attention of decision factors. This possibility should be exploited in order to reduce the risk of victimization of motor vehicle occupants and other traffic participants.Key words: motor vehicle, indicator, risk, road, safety, traffic

Fig. 1. Direction and evolution in time of the number of deceased people in road accidents which occurred in romania, reported to a million of inhabitants [2]

23


the size of traffic safety problems in a simple and effective tool, of planning and monitoring the progress related to traffic safety, whose core is to be represented by the evaluation and technique of decision-making in this area [10], [11] and [12].In most scientific papers researchers present the idea according to which the combination of SPIs in a CRSPI is an intensive methodological process, consisting of various stages [13]. It is obvious that the combination of all information in one single indicator has advantages and disadvantages, but these must be manifested in balanced doses [10].The “Sunflower” approach described the domain of road traffic safety as being a pyramid (Fig. 3) formed of various levels. From bottom to the top [9]:safety measures and programs (as a performance of the traffic safety policy);performance indicators

in the safety domain, SPIs (as intermediate results);the number of the deceased and / or of injured people coming from road traffic accidents (as final results);social costs of road traffic accidents.In order to take into account the substantive requirements of the system or the contextual requirements, researchers have added another layer to the bottom, entitled “structure and culture” [9].A CRSPI would combine the main levels of the road traffic safety pyramid, if the fact that, in general, an index results from the combination of a set of indicating values and a set of weights, is taken into account. The composition of an index as an average of the values of all indicators is simple to achieve, but inappropriate due to the fact that, for example, the importance of two indicators could significantly differ, and the idea of

complete compensation between good scores and bad scores would be unacceptable. Therefore, in the reference literature, the weights assigned to SPIs are evaluated by researchers with a great amount of seriousness [9] and [14].3.2. The design of composite indicators of road traffic safetyFrom the reference literature it appears that the design of a CRSPI consists of attending at least two main stages: establishing the SPIs to be aggregated and choosing the method of aggregation.The aggregation of the SPIs is the process of combining values into a single score, so that the final result to take into account all individual values in a specific manner [13].Methods commonly utilized for aggregating the SPIs are weighting techniques consisting of assigning a weight to each of the selected indicators, according to their importance, in such a manner that they contribute adequately to the

CRSPI. The most commonly used aggregation methods for estimating the CRSPI are roughly classified into two categories (participatory methods and statistical methods) and refer to: equal weighting, budget allocation, the analytic hierarchy process, the envelopment analysis of data, the analysis of the principal component, factor analysis, the Fuzzy Delphi method, the Delphi gray method, the Fuzzy hierarchical TOPSIS model etc. [14].Modern versions of assessment tools for road safety performances are designed through the exploitation of a new vision regarding the selection and aggregation of SPIs in pairs (so that the construction of CRSPI does not depend only on the selection of indicators, but to take into consideration the basic relationship between indicators, including unit of measure, the degree of non-compensation between the respective indicators, their hierarchical structure, etc.). For the application of such versions, the following SPIs were selected:the total number of road traffic accidents that resulted in fatalities, which occurred in a certain time interval, on a given area – I

1;the total number of vehicles involved in all road traffic accidents that resulted in fatalities, which occurred in a certain time interval, on a given area – I2;the total number of fatalities that resulted from road traffic accidents, which occurred in a certain time interval, on a given area – I3;the total number of serious road traffic accidents, which occurred in a certain time interval, on a given area – I4;the total number of slightly road traffic accidents, which occurred in a certain time interval, on a given area – I5;the total number of vehicles involved only in slightly road traffic accidents, which occurred in a certain time interval, on a given

Fig. 2. road traffic safety indicators [7]

24


area – I6.After this, it was considered that, since any road traffic accident requires the involvement of at least one vehicle, then I1 and I2 are comparable and, moreover, are comparable in a conditioned manner (aspect resulting from the fact that, for any vehicle to be involved in an accident, the collision itself should be consumed). Moreover, since a traffic accident which involves the death of individuals may have as a consequence the existence of other casualties, and serious injuries (vice versa is equally valid in such a situation), the I3 and I4 indicators are comparable. In addition, the occurrence of a fatal road traffic accident (which resulted in the death of one or more people) or resulting only with seriously injured people is conditioned by the consumption of a collision and by the number of vehicles involved in such collisions, and due to reasons of this nature, the pair (I3, I4) is conditionally comparable with the pair (I1, I2) [14].The function of the composite index of road safety performance was formed through the contribution of all marginal functions of safety performance, for any given normalized achievements of indicators I1, I2, I3, I4, I5, and I6 as following [14]:

(1)

(2)

(3)in which:

; represents the number of Euler;

, with defined through the relations (4) and (6);

, with defined through the relations (4) and (5);

, , , , and are normalized accomplishments of the indicators I1, I2, I3, I4, I5, and I6; The marginal functions for the pairs of indicators and

are given by the relations (5) and respectively (6) [14]:

(4)

(5)

(6

where: is the bench Heaviside

function;, with

defined through the relations (4) and (5);

, with defined through the relations (4) and (5).

It is important to mention that, in comparison with other relations, for the relation (5),

, and indicators and represent sub-sets of

indicators and (reason for which it has been concluded that only two marginal functions of the performance index in the safety domain are necessary).4. ConClusionsThe road safety management in Romania, understood as a system or complex institutional structure that involves the interaction and cooperation of organizations which support tasks and processes necessary in order to prevent and reduce the victimization produced by traffic accidents, requires the establishment and accurately measurement of the most relevant SPIs for use in the design of CRSPI [15].

This possibility should be exploited in order to reduce the risk of victimization of motor vehicle occupants and other traffic participants.The main objections of those who believe that, once a set of SPIs has been created, it is no longer required to create the design of a CRSPI, are related to the arbitrary nature of the weighting process through which variables are combined, to the fact that political misleading messages can be generated, where CRSPI is constructed or misinterpreted, to the fact that CRSPI can be used in an abusive manner (for example, to support a desired policy, if its formation process is not transparent and / or it has no statistical foundation or it not based on conceptual principles) etc. [10].

rEFErENcEs[1] Organizaţia Mondială a Sănătă-ţii, 2012, Iulie, (online) http://www.who.int/gho/road_safety/mortality/traffic_ deaths_distribution_text /en/index.html[2] Fabrice Hamelin et al., „Scien-ces et politiques de securite routiere. Comparaisons européennes“, Sep-tember 2011, Rapport Final Projet ANR-07-TSFA-002-01 ROSARINE (Road Safety Research in Europe)[3] George Yannis et al., „Road safety performance indicators for the in-terurban road network“, Accident Analysis and Prevention, vol. 60, pp. 384 – 395, November 2013[4] Shalom Hakkert, Victoria Gitel-man, and Martijn A. Vis, „Road Safety Performance Indicators: Theory“, 2007, Deliverable D3.6 of the EU FP6 project SafetyNET[5] Shalom Hakkert and Victoria Gitelman, „Road Safety Performan-ce Indicators: Manual“, 2007, Deli-verable D3.8 of the EU FP6 project SafetyNET[6] Gerard I.J.M. Zwetsloot et al., „The case for research into the zero ac-cident vision,“ Safety Science, vol. 58, pp. 41 – 48, April 2013[7] Victoria Gitelman, Etti Doveh, and Shalom Hakkert, „Designing a composite indicator for road safety“, Safety Science, vol. 48, no. 9, pp. 1212 – 1224, January 2010, DOI: 10.1016/j.ssci.2010.01.011[8] Fred Wegman and Siem Oppe, „Benchmarking road safety perfor-mances of countries“, Safety Scien-ce, vol. 48, no. 9, pp. 1203 – 1211, February 2010, DOI: 10.1016/j.ssci.2010.02.003[9] Tingvall, C., et al., „The properties of Safety Performance Indicators in

target setting, projections and safety design of the road transport system“, Accident Analysis and Prevention, vol. 42, no. 2, pp. 372 – 376, March 2010, DOI: 10.1016/j.aap.2009.08.015[10] Zhuanglin Ma, Chunfu Shao, Sheqiang Ma, and Zeng Ye, „Con-structing road safety performance in-dicators using Fuzzy Delphi Method and Grey Delphi Method“, Expert Systems with Applications, vol. 38, no. 3, pp. 1509 – 1514, 2011, DOI: 10.1016/j.eswa. 2010.07.002[11] Elke Hermans, Da Ruan, Tom Brijs, Geert Wets, and Koen Van-hoof, „Road safety risk evaluation by means of ordered weighted averaging operators and expert knowledge“, Knowledge-Based Systems, vol. 23, no. 1, pp. 48 – 52, 2010, DOI: 10.1016/j.knosys.2009.07.004[12] Bronagh Coll, Salissou Moutari, and Adele H. Marshall, „Hotspots identification and ranking for road safety improvement: An alternative approach“, Accident Analysis and Pre-vention, vol. 59, pp. 604 – 617, Oc-tomber 2013, (online) http://dx.doi.org/10.1016/j.aap.2013.07.012[13] Eleonora Papadimitriou and George Yannis, „Is road safety mana-gement linked to road safety perfor-mance?“, Accident Analysis and Preven-tion, vol. 59, pp. 593 – 603, Octomber 2013[14] European Commission, 2014, Mobility and Transport, (online) http://ec.europa.eu/transpor t/index_en.htm[15] Elke Hermans, Filip Van den Bossche, and Geert Wets, „Com-bining road safety information in a performance index“, Accident Analysis and Prevention, vol. 40, no. 4, pp. 1337 – 1344, February 2008

Fig. 3. road traffic safety pyramid [10]

25


Between 23rd and 24th of October, 2014 took place, at Craiova, the fi-nal stage of the first edition of the national contest for students in automotive engineering “Professor eng. Constantin Ghiulai” within the field of Automotive Dynamics. The contest took place in the same with the International Congress of the Romanian Society of Automo-tive Engineering - SIAR. The Con-test’s organizer was SIAR, too.The national stage of the contest was attended by 28 students, rep-resenting 7 universities, as follows: “Transilvania” University of Brasov, “Politehnica” University of Bucha-rest, Technical University of Cluj-Napoca, University of Craiova, University of Oradea, University of Pitesti and “Politehnica” University of Timisoara.Previously, all these university successfully organized the local (university level) stage of the com-petition. About 200 undergradu-ate students from the “Automotive Engineering” and “Transporta-tion Engineering” branches took attended this stage. The delegate

teams of the universities that have represented institutions to the “Great Final” were made of the win-ners of the local stage.The competition based on a

common topic and references, is-sued by a team of specialized pro-fessors as well as on a nationally approved regulation.The AVL Group Romania

sponsored the activity and the final results are given below:First prize – Radu-Daniel MUREŞAN, Technical University of Cluj-Napoca

First Placeradu-Daniel mureŞan technical university of

Cluj-napoca

second Placebogdan-ioan DRAgoŞtechnical university of

Cluj-napoca

Third Placeandrei-tiberiu borborean

„Politehnica” university of timișoara

The National Contest for Students in Automotive Engineering „Professor Eng. CONSTANTIN GHIULAI”. Domain „Dynamics of Vehicles”. First Edition, 2014Concursul Naţional Studenţesc de Inginerie a Autovehiculelor „Prof. univ. ing. CONSTANTIN GHIULAI”Domeniul „Dinamica autovehiculelor”. Ediţia I-a, 2014

Professor Dr.-Ing.Minu MitreaSecretary General of SIAR

[email protected]

26


Second prize – Bogdan-Ioan DRAGOŞ, Technical University of Cluj-NapocaThird prize – Andrei-Tiberiu BOR-BOREAN, “Politehnica” Univer-sity of TimisoaraThe team contest’s prizes were awarded as follows:First prize – The team of Technical University of Cluj-NapocaSecond prize – The team of “Po-litehnica” University of TimisoaraThird prize – The team of Univer-sity of PitestiAll the participant students were granted “Merit Diploma” for their outstanding results during the competition.The special prize of the contest, pro-vided by CADWorks Craiova Com-pany has been awarded to student

Radu-Daniel MUREŞAN from Technical University of Cluj-Nap-oca, consisting in a “Garmin GPS Navigation System”. The first edi-tion of the contest took advantage of the logistic support provided by the Department of Automotive, Transportation and Industrial En-gineering of the Faculty of Mechan-ics from the University of Craiova. SIAR will organize the second edi-tion of the contest between 12 and 14 of November 2015, in the same time with the International Con-gress on Automotive Engineering ESFA 2015, at “Politehnica” Uni-versity of Bucharest.

For further information, please feel free to contact http://siar.ro/siar-junior/.

The 9th edition of the international congress – ESFA 2015

Important Dates:

CONTACT: Societatea Inginerilor de Automobile din România Facultatea de Transporturi Parter, sala JC005 Splaiul Independenței nr. 313 sector 6 Cod poștal 060042 București Tel./Fax: +4.021.316.96.08

Universitatea Politehnica din București Facultatea de Transporturi

Departamentul de Autovehicule Rutiere Splaiul Independenței nr. 313 sector 6

Cod poștal 060042 București

Tel./Fax: +4.021.402.95.48

auto test 3eISSN 2284-5690 • pISSN 1842-4074

Ingineria · Authors: Amalia Ana DASCĂL, Tiberiu Nicolae MACARIE Publisher: PIM Iași Published:...

Documents

Transcript of Ingineria · Authors: Amalia Ana DASCĂL, Tiberiu Nicolae MACARIE Publisher: PIM Iași Published:...