A. Erman TekkayaWerner HombergAlexander Brosius Eds.

60 Excellent Inventions in Metal Forming

60 Excellent Inventions in Metal Forming

A. Erman Tekkaya � Werner Homberg �Alexander BrosiusEditors

60 Excellent Inventions inMetal Forming

Editors

A. Erman TekkayaInstitut für Umformtechnik und LeichtbauTechnische Universität DortmundDortmund, Germany

Werner HombergLehrstuhl für Umformende und SpanendeFertigungstechnikUniversität PaderbornPaderborn, Germany

Alexander BrosiusInstitut für FertigungstechnikTechnische Universität DresdenDresden, Germany

ISBN 978-3-662-46311-6 ISBN 978-3-662-46312-3 (eBook)DOI 10.1007/978-3-662-46312-3

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Preface

This book is dedicated to the 60th birthday of Matthias Kleiner by his friends from theinternational forming community. The title and content of this book “60 Excellent In-ventions in Metal Forming” corresponds to the essence of the scientific and technicalcontribution of Matthias Kleiner, who is very well known for his creativity, out-of-the-boxthinking, and innovations. He is not an engineer who is only interested in his specialistarea and deals with the optimization of individual technical details. Instead, he is steadilyinterested in distinct topics and open to new ideas and opportunities. Matthias Kleiner isnot a scientist who is doing research behind closed doors. Rather, he seeks contact and ex-change with engineers, scientists from other disciplines, and every other people. By this,he defines the notion ‘open minded’ in a new and personal way. He appreciates the in-spirations and the opportunities that arise from this contact and exchange and understandshow to collate them to create something fundamentally new. He always understands bethe multiplicator as well as the catalyzer in one person and motivates other scientists andhis own team in a participating and enjoyable way. Thus, he created many innovative, un-conventional ideas, which were often ahead of their time. Numerous patents, publications,and doctoral theses are clear indicators for his success.

The scientific career in academia offered him the necessary environment for devel-oping and trying out unconventional ideas. He initiated several new research activitiesthat achieved international recognition such as Curved Profile Extrusion, Flexible Manu-facturing Chains for Lightweight Structures, Hydroforming, Bending, Advancement andModelling of Electromagnetic Forming Processes, and others. Besides his engineeringwork, Matthias Kleiner has been involved for many years with the system of academicresearch. He has developed clear-sighted visions for the improvement of the frame con-ditions for research while never losing sight of solutions to obvious problems. MatthiasKleiner is a member of numerous local and foreign academies and scientific institutions,including the German Academy of Natural Sciences Leopoldina, the Berlin-BrandenburgAcademy of Sciences, the Academia Europaea, the German Academy of Engineering Sci-ences (acatech), the International Academy for Production Engineering and the ScientificSociety of Production Technology (WGP), and the International Academy for ProductionEngineering (CIRP).

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vi Preface

The 60th birthday of Matthias Kleiner is a wonderful opportunity to recognize his im-pressed and unique national and international contributions to the metal forming commu-nity and the research community in general. As the editors, we are very much impressedabout the spontaneous and sincere readiness of all colleagues worldwide to accept ourinvitation to contribute to this book. This is obviously another clear indicator of the in-ternational and national recognition of Matthias Kleiner as a scientist, a colleague, andfriend.

We would like to thank all colleagues of the CIRP, the colleagues of the JapaneseSociety for Technology of Plasticity (JSTP) – especially Professor Kozo Osakada fororganizing and editing the Japanese contributions –, the colleagues of the German As-sociation of Metal Forming (AGU), Mr. Thomas Lehnert (Springer-Verlag) and his teamfor supporting our idea and accepting to print this unique book through the distinguishedpublisher Springer-Verlag, Dr. Nooman Ben Khalifa (Chief Engineer for Research, IUL)for organizing the structure of the book, Dr. Frauke Maevus (IUL) and Dr. RamonaHölker (IUL) for their contribution to the preface and introduction, Mr. Lars Hiegemann(research assistant at the IUL) for preparing the print of the book and keeping the contactwith all authors and the publisher, and all research assistants at the IUL for reviewing thecontributions.

The Editors, January 2015 A. Erman TekkayaWerner Homberg

Alexander Brosius

Matthias Kleiner wrote his doctoral dissertation at Dortmund University in 1987 on thetopic “Multiprocessor Control in Metal Forming”. He habilitated in 1991 on the topic“Process Simulation in Metal Forming”. From 1994 to 1998, Matthias Kleiner built theChair of Design and Manufacturing at the newly founded Brandenburg Technical Univer-sity of Cottbus (BTU Cottbus) as a full professor. In 1997 Matthias Kleiner was awardedthe Gottfried Wilhelm Leibniz Prize by the DFG (Deutsche Forschungsgemeinschaft –German Research Funding Organization). He was appointed as the Head of the Chair ofForming Technology of Dortmund University in 1998. In 2004 he transformed the chairinto today’s Institute of Forming Technology and Lightweight Construction (IUL – Institutfür Umformtechnik und Leichtbau). 2007 he was elected, as the first engineer in history,as president of the DFG for a term of 6 years. Since 2014 Matthias Kleiner has been thepresident of the Leibniz association, where he can contribute with his excellent skills tolead a large and successful research association, his understanding of the problems of thescientific research in Germany, and his visions towards a European research landscape.

Introduction

A. Erman Tekkaya, Nooman Ben Khalifa, Ramona Hölker, andLars Hiegemann

Metal forming is a symbiosis of tradition and innovation driven by scientific and tech-nological inventions. Comprehensive developments in materials, tooling and machinerylead permanently to new or improved metal forming processes and products. The drivingmotor in metal forming are the technological innovations which lead to new processesor process combinations resulting in novel or improved products. The enormous boost ininnovations that occurred in the last decades was only possible by a concurrent develop-ment in analysis methods and measurement techniques, which act as the enabling toolfor metal forming innovations by providing a physical insight to the processes. This isdifferent than in other manufacturing technologies, for instance as in machining, since theeffect of actuators in metal forming covers large parts of the workpiece volume based oncomplicated physical response functions.

Figure 1 shows the new process families that have been invented in the last 60 years.Most technological innovations in this period are related to sheet metal forming, except

Fig. 1 60 years of inventions in metal forming – overview of the main active development period inselected areas

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viii Introduction

cold forging, tailored rolling, and parts of the micro forming technology. The analysis in-novation can be located in two fields: analytical methods and measurements (see Fig. 1).Upper bound methods and slip line field methods are even today valuable tools for de-veloping insight in complicated metal forming processes. Impressive developments inanalyzing the microstructure enabled new and powerful computational methods, the so-called multi-scale methods. These trigger the transition of the phenomenological approachof plasticity to a physics-based approach today.

The basic drivers of these process innovations came in various streams of focused re-search and development, as shown in Fig. 2. The stream of near-net shape forming boostedthe field of cold forging. The increasing product variance (especially in the automotiveindustry) initiated the flexible forming process development and inventions. Incremen-tal sheet forming methods were basically developed in this era. The awareness of theanthropogenic greenhouse effect enforced energy savings in all branches of design andmanufacturing, leading to environmentally benign forming processes. Today, these ac-tivities include most of the lightweight efforts, but also cover dry forming processes orlow acoustic emission processes. A natural extension of the environmentally consciousdesign of products is the deterministic setting and utilization of product properties alteredin forming processes. This recent development will be one of the main research trends infuture decades. Developments in damage mechanics and multi-scale modelling will be thebasis of this stream. Finally, it is believed that the precise setting of parameters, despiteof several uncertainties in the material, process, environment etc., will be enabled by theclosed-loop control of forming processes and forming process chains including the heattreatment processes. This last trend is just starting initiated by the collaborative work ofvarious CIRP colleagues.

This book aims at demonstrating the enormous innovation affinity of metal forming bycompiling the most important 60 inventions of the last decades. It must be emphasizedthat these inventions are not exhaustive in any way. Obviously, some of the brilliant ideas

Fig. 2 Main trends in metal forming with a future projection

Introduction ix

have been left unmentioned in this book. Nevertheless, we think that this work still canserve the aim mentioned before.

The book covers the 60 new ideas in 9 parts:

� Part 1: Material Characterization and Tribology (6 inventions)� Part 2: Modelling (5 inventions)� Part 3: Sheet Metal Forming (9 inventions)� Part 4: Incremental Forming (7 inventions)� Part 5: Shear Cutting (5 inventions)� Part 6: Rolling (6 inventions)� Part 7: Extrusion and Hot Forging (6 inventions)� Part 8: Cold Forging (9 inventions)� Part 9: Tube and Profile Forming (7 inventions)

Part 10 collects further developments covering 7 additional inventions and ideas.The inventions in this book originate from 10 countries: Denmark, France, Germany,

Italy, Japan, Poland, Portugal, Romania, United Kingdom, and the United States. It isnoteworthy that several authors from many more countries are involved in these inven-tions, demonstrating that the forming innovation is internationally widespread.

The authors have confidence that the next decades will bring out many additional in-ventions and ideas that will improve the technology of metal forming even further and,hence, serve the wealth generation for the society in the same manner as they have in thepast decades. The authors also hope that this book will stimulate young students, youngresearchers, and young engineers in the field of metal forming to recognize the huge op-portunity for creativity of this vivid field of manufacturing engineering. At the same time,they hope that it is also recognized how metal forming technology goes hand in hand withanalysis methods in mechanics, metal science, chemistry as well as measuring techniques.The terrific developments in mechatronic systems (including sensors and actuators), dig-ital technology, and tailoring materials on nano-scale are wonderful opportunities for thefuture.

The authors also hope that this impressive collection of inventions in technology andscience inspires national funding agencies and university administrations to recognize thehuge added value of metal forming research for the society. Metal forming is obviouslynot an ancient technology that has exceeded its shelf-life for research. In fact, it is anever-developing technology utilizing all available scientific knowledge and methodolo-gies. Metal forming is an enabling technology without which it would be not possible torealize many of the innovations in biotechnology (e. g. implants, stens), in clean energygeneration and transport (e. g. wind mills, super-conductors), space missions (e. g. boost-ers, structures), and many more. Metal forming could not enable all these technologieswithout evolving itself as presented in this book.

Table of Contents

Part I Material Characterization and Tribology

Novel Method for Combined Tension and Shear Loadingof Thin-Walled Tubes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Christopher P. Dick and Yannis P. Korkolis

An Innovative Procedure for the Experimental Determinationof the Forming Limit Curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Dorel Banabic, Lucian Lazarescu, and Dan-Sorin Comsa

Sheet Material Characterization with the In-Plane Torsion Test:Cyclic Loading, Grooved Specimen and Twin Bridge Specimen . . . . . . . 17Heinrich Traphöner, Qing Yin, and A. Erman Tekkaya

Friction Analysis in Bulk Metal Forming . . . . . . . . . . . . . . . . . . . . . . . . . 23Laurent Dubar, André Dubois, and Mirentxu Dubar

Flow Stress Measurement in Upsetting Test with Grooved Platens . . . . . . . . 29Kozo Osakada

Equipment for Off-line Testing of Sheet Tribo-systems . . . . . . . . . . . . . . . . 35Ermanno Ceron and Niels Bay

Part II Modelling

Anisotropic Yield Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43Frédéric Barlat and Hyuk Jong Bong

BBC2005 Yield Criterion Used in the Numerical Simulationof Sheet Metal Forming Processes . . . . . . . . . . . . . . . . . . . . . . . . . . 49Dorel Banabic and Dan-Sorin Comsa

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The Impact of M-K Model on Development of Formability Assessmentin Sheet Metal Forming Processes . . . . . . . . . . . . . . . . . . . . . . . . . . 55Andrzej Kocanda

Cyclic Plasticity Model for Accurate Simulation of Springbackof Sheet Metals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61Fusahito Yoshida and Takeshi Uemori

Fast Semi-analytical Approach for Deep Drawing Processes . . . . . . . . . . . . 67Alexander Brosius and Tim Cwiekala

Part III Sheet Metal Forming

Vaporizing Foil Actuator: a Tool for Creating High-Pressure Impulsesfor Metalworking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77Anupam Vivek, Geoffrey A. Taber, Jason R. Johnson, and Glenn S. Daehn

Hybrid Deep Drawing Tools for High Strength Steels . . . . . . . . . . . . . . . . . 83Thomas Mennecart, Jörg Kolbe, and Matthias Kleiner

High-Accuracy & High-Rigidity Forming Machines (UL Presses) . . . . . . . . . 89Takaaki Imura

Short-Cycle-Stretch-Forming (SCS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95Mathias Liewald, Philipp Schmid, Matthias Schneider, and Apostolos Pa-paioanu

Sheet-Bulk Metal Forming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101Daniel Gröbel, Thomas Schneider, and Marion Merklein

Electromagnetically Assisted Sheet Metal Stamping and Deep Drawing . . . . . 107Glenn S. Daehn, Anupam Vivek, and Jianhui Shang

Dry Metal Forming – a Green Approach . . . . . . . . . . . . . . . . . . . . . . . . . 113Frank Vollertsen, Hendrik Flosky, and Thomas Seefeld

Forming of Tailored Blank . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119Toshiyuki Takasago and Takao Iwai

New Forming Technologies Using Screw Type Servo Press . . . . . . . . . . . . . . 127Junichi Endou and Chikara Murata

Table of Contents xiii

Part IV Incremental Forming

Non-circular Spinning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137Sebastian Härtel and Birgit Awiszus

Hybrid Sheet Metal Processing Center . . . . . . . . . . . . . . . . . . . . . . . . . . 143David Bailly, Laura Conrads, and Gerhard Hirt

Friction-Spinning – Innovative Opportunity for Overcoming ProcessLimits in Spinning Processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149Werner Homberg and Benjamin Lossen

Single Point “Dieless” Incremental Forming . . . . . . . . . . . . . . . . . . . . . . . 155Masaaki Amino, Masashi Mizoguchi, Yuji Terauchi, and Trent Maki

TwinTool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161Lukas Kwiatkowski and A. Erman Tekkaya

Laser Adjustment Using Actuators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167Hinnerk Hagenah and Manfred Geiger

Flexible Asymmetric Spinning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173Omer Music and Julian M. Allwood

Part V Shear Cutting

Micro Hole Piercing with a Slant Angle . . . . . . . . . . . . . . . . . . . . . . . . . . 181Tomomi Shiratori and Takafumi Komatsu

Fine Blanking of Helical Gears . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187Andreas Feuerhack, Daniel Trauth, Patrick Mattfeld, and Fritz Klocke

Edge-Fracture-Tensile-Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193Martin Feistle, Michael Krinninger, Isabella Pätzold, and Wolfram Volk

Reduction of Vibrations in Blanking by MR Dampers . . . . . . . . . . . . . . . . 199Andrea Ghiotti, Paolo Regazzo, Stefania Bruschi, and P. Francesco Bariani

Force Reduction During Blanking Operations of AHSS Sheet Materials . . . . . 205Andreas Mackensen, Matthias Golle, Roland Golle, and Hartmut Hoffmann

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Part VI Rolling

Flexible Rolling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213Markus Grüber, Reiner Kopp, and Gerhard Hirt

Vertical Twin-Roll Strip Casting of Steel . . . . . . . . . . . . . . . . . . . . . . . . . 219Markus Daamen, Michele Vidoni, and Gerhard Hirt

Pair Cross Type Rolling Mill for Hot Rolling . . . . . . . . . . . . . . . . . . . . . . 225Shunji Omori, Hiroyuki Hino, Kanji Hayashi, and Hideaki Furumoto

Endless Hot Strip Rolling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233Kanji Hayashi, Hideyuki Nikaido, and Hideaki Furumoto

6-High Type Rolling Mill for Cold Rolling . . . . . . . . . . . . . . . . . . . . . . . . 239Toshiyuki Kajiwara, Hidetoshi Nishi, Yasutsugu Yoshimura, and Hideaki Fu-rumoto

Riblet Rolling on Ti6Al4V Compressor Blades . . . . . . . . . . . . . . . . . . . . . 245Michael Terhorst, Daniel Trauth, and Fritz Klocke

Part VII Extrusion and Hot Forging

TR Process for Forging Heavy Crankshafts . . . . . . . . . . . . . . . . . . . . . . . 253Tadeusz Rut, Wojciech Walczyk, Andrzej Milenin, and Maciej Pietrzyk

Chip Extrusion with Integrated Equal Channel Angular Pressing . . . . . . . . . 261Matthias Haase and Nooman Ben Khalifa

Non-graphite Water Soluble Lubricant for Hot Forging . . . . . . . . . . . . . . . 267Nobuhiro Ikeda

Composite Extrusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275Christoph Dahnke, Thomas Kloppenborg, Martin Schwane, Marco Schikorra,Daniel Pietzka, Matthias Kleiner, and Michael Schomäcker

Novel Billet Design for Co-extrusion of Bi-metallic Shapes and Tubes . . . . . . 281Mario E. Epler and Wojciech Z. Misiolek

Curved Profile Extrusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287Alessandro Selvaggio, Dirk Becker, Alexander Klaus, Dieter Arendes, andMatthias Kleiner

Table of Contents xv

Part VIII Cold Forging

Joining of a Shaft-Hub Connection by Lateral Extrusion . . . . . . . . . . . . . . 295Florian Dörr and Mathias Liewald

Divided Flow Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301Kazuyoshi Kondo

Enclosed Die Forging Using Die Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . 307Yoshihiro Ishihara and Kozo Osakada

Joining of Serrated Shaft with Holed Disk by Indentation . . . . . . . . . . . . . . 313Kazuhiko Kitamura, Kenji Hirota, Yoshihiko Ukai, and Kei-ichi Matsunaga

Development of Orbital Forging Processes by UsingMarciniak Rocking-Die Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . 319Andrzej Kocanda

Double Cup Extrusion Test to Evalute Lubricants for Cold Forging . . . . . . . 325Taylan Altan and Gracious Ngaile

Extrusion of Scroll Against Counter Pressure . . . . . . . . . . . . . . . . . . . . . . 331Hidekazu Hayashi and Kozo Osakada

High-Performance Permanent Magnets by Cold Forming . . . . . . . . . . . . . . 337Peter Groche and Lennart Wießner

New Cold Forging Lubricant Replacing Zinc Phosphate Coating . . . . . . . . . 343Zhigang Wang and Shinobu Komiyama

Part IX Tube and Profile Forming

Incremental Tube Forming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 351Christoph Becker, Matthias Hermes, and A. Erman Tekkaya

Incremental Profile Forming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 357Goran Grzancic, Christoph Becker, and Matthias Hermes

CNC Tube Forming Method for Manufacturing Flexiblyand 3-Dimensionally Bent Tubes . . . . . . . . . . . . . . . . . . . . . . . . . . . 363Makoto Murata and Takashi Kuboki

Mechanical Joining of Tubes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 369Luis M. Alves and Paulo A.F. Martins

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Fabrication of Seamless Metallic Liners for COPV‘s . . . . . . . . . . . . . . . . . 375Luis M. Alves and Paulo A.F. Martins

Torque Superposed Spatial bending . . . . . . . . . . . . . . . . . . . . . . . . . . . . 381Matthias Hermes, Daniel Staupendahl, and Matthias Kleiner

Further Development on Tube Hydroforming . . . . . . . . . . . . . . . . . . . . . . 387Ken-ichi Manabe and Sadakatsu Fuchizawa

Part X Further Developments

In-Situ Measurement of Loading Stresses by Means of X-ray Diffraction withMulti-State Sheet Specimen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 397Alper Güner and A. Erman Tekkaya

Smart Hot Stamping for Ultra-high Strength Steel Parts . . . . . . . . . . . . . . . 403Ken-ichiro Mori

Technologies for Forming and Foaming of Aluminium Foam Sandwich . . . . . 409Bernd Viehweger and Alexander Sviridov

Plastic Consolidation of Metal Matrix Composites by Pressure Cycling . . . . . 415Glenn S. Daehn

Process-Integrated Heat Treatment of Hot Forged Components . . . . . . . . . . 421Adis Huskic, Mohammad Kazhai, and Bernd-Arno Behrens

Micro-Tube Hydroforming System Based on Floating Die Assembly . . . . . . . 427Gracious Ngaile and James Lowrie

Tube Drawing with Tilted and Shifted Die . . . . . . . . . . . . . . . . . . . . . . . . 433Adele Carradò, Farzad Foadian, and Heinz Palkowski

Erratum to: 60 Excellent Inventions in Metal Forming . . . . . . . . . . . . . . . . E1A. Erman Tekkaya

Part IMaterial Characterization and Tribology

Novel Method for Combined Tension and ShearLoading of Thin-Walled Tubes

Christopher P. Dick and Yannis P. Korkolis

1 Motivation

The bulk deformation processes that are used to produce thin sheets and tubes intro-duce preferred crystallographic orientations, or texture, to them. As a result of that, thesheets and tubes exhibit plastic anisotropy, which affects the way that they flow plasticallyand, consequently, their failure limits. Establishing the plastic anisotropy and calibratingappropriate material models is critical for accurate numerical simulations of forming pro-cesses and often determines whether the simulation agrees with the experiment or not [1].Typical experiments for characterizing the anisotropy of sheet materials are tension tests atdifferent angles to the rolling direction, biaxial testing of cruciform specimens, hydraulicbulge tests as well as a variety of shear tests [2]. For the case of tubes, the most flexibleand well-controlled experiments are the combined tension and torsion, or combined ten-sion and internal pressure loading [3, 4]. However, both require sophisticated equipmentand are relatively complex to perform.

Two experiments for tubes, which are simple to perform and require only a universaltesting machine are described in this paper: a) the Ring Hoop Tension Test, or RHTT [5],and b) the Ring Plane-Strain Tension test, or RPST. In both experiments, a ring is extractedfrom the parent tube and a test-section is machined on it. The resulting specimen is thenplaced over two lubricated, close-fitting, D-shaped mandrels. The mandrels are parted ina universal testing machine. Care is taken so that the test-section of the RHTT or RPSTspecimen remains on one of the mandrels throughout the experiment. As a result of that,the curvature of test-section does not change and hence it experiences only stretching.

Christopher P. Dick � Yannis P. Korkolis �University of New Hampshire, Durham, USAe-mail: Yannis.Korkolis@unh.edu

3© Springer-Verlag Berlin Heidelberg 2015A. E. Tekkaya et al. (eds.), 60 Excellent Inventions in Metal Forming,DOI 10.1007/978-3-662-46312-3_1

4 C. P. Dick and Y. P. Korkolis

2 Ring Hoop Tension Test

A close-up of the RHTT specimen is shown in Fig. 1. A sandwich of oil and Teflon tapehas been used to reduce the friction between the specimen and the mandrels. Also, thespecimen has been painted with a random speckle for Digital Image Correlation (DIC)purposes. A valid concern is to what extent does the contact with the mandrel and theresulting friction affect the stress distribution inside the test-section, and make it deviatefrom the ideal uniaxial case. This was investigated with the aid of finite element analysis(FEA) using solid elements, to capture the stress fields as accurately as possible. Thematerial was modeled as a finitely-deforming, rate-independent elastoplastic solid, usingthe J2 flow theory of plasticity with an associated flow-rule. The hardening curve of Al-6061-T4 was input to the simulations. The FEA results for the hoop strain are shown inFig. 2. The hoop stress is uniform inside the test section and remains elastic in the restof the specimen. The two regions that are between the parting mandrels experience bothstretching and (un-)bending, and develop a through-thickness stress gradient that is visiblein Fig. 2. A very detailed probing of this model [6] showed that the contact pressure atthe test-section area is very close to being uniform, and that the stresses that are inducedby it are negligible, provided that the specimen-mandrel friction remains below 0.15–0.2.The investigation also established that the contact pressure in a well-lubricated RHTTexperiment does not have a very different effect on the specimen from that of internalpressure in an inflated tube.

In RHTT experiments on extruded Al-6061-T4 tubes (OD= 60mm, t = 3mm), the ap-parent hoop stress-strain response was measured and found to be different than the axialone. After accounting for the tube eccentricity, specimen-mandrel friction and specimenpreparation, the remaining difference between the axial and hoop responses was attributedto material anisotropy (Fig. 3). The DIC technique was used [6] to probe the local strainfields during RHTT, which enabled the determination of the R-values, or Lankford coeffi-

Fig. 1 The Ring Hoop TensionTest [6]

Novel Method for Combined Tension and Shear Loading of Thin-Walled Tubes 5

Fig. 2 Finite element predic-tion of the hoop stress in theRHTT (Units: MPa) [6]

cients of this material. The R-values are seen to evolve with plastic deformation (Fig. 4).The RHTT experiment established that the R-value in the hoop direction is greater than 2.

The RHTT experiment can also be used to probe the response of welds in eitherelectrical-resistance-welded (ERW) or extruded through porthole-die tubes [7]. In con-trast to tube inflation experiments, the RHTT allows the direct loading of the weld inuniaxial tension transversely to it.

Fig. 3 Nominal stress-strain responses in the axial and hoop direction of the tube [6]

6 C. P. Dick and Y. P. Korkolis

Fig. 4 Evolution of the R-values during deformation, showing axial-hoop anisotropy [6]

3 Ring Plane-Strain Tension Test

The RHTT experiment can be used to determine the hoop stress-strain response of a tube.The plastic response along additional loading paths can be probed with the RPST exper-iment [8]: a relatively wide and short test-section is prepared on a ring, which is thentested on the same equipment as the RHTT experiment. The wide shoulders above andbelow the test-section remain elastic during loading and thus they are stiffer than the plas-tically deforming test-section. Hence, they prevent the deformation of the test-section inthe direction parallel to it, enforcing essentially tension-under-plane-strain conditions. Togenerate additional loading paths, the orientation of the test-section is rotated with re-spect to the tube generatrix, to extend along a helical arc. By controlling the inclinationof the test-section, different combinations of tension and shear on the test-section can beinduced. Three such specimens are shown in Fig. 5.

Fig. 5 Ring Plane-Strain Tension specimens with inclined test-sections at a 15o, b 30o and c 45o tothe tube axis [8]

Novel Method for Combined Tension and Shear Loading of Thin-Walled Tubes 7

Fig. 6 Evolution of log. strain fields along the test-section, showing that throughout most of theexperiment plane-strain conditions prevail at the central portion of test-section. a Extensional and bshear strains [8]

The DIC technique was used to confirm that plane-strain conditions exist during testing,as seen in Fig. 6 for a specimen where the test-section was inclined by 45o. The DICresults reveal that these conditions are met only at the central portion of the test-section.The strain parallel to the test-section deviates from zero towards the two edges, indicatinga transition from plane-strain to uniaxial tension. Interestingly, the shear strain (Fig. 6b)remains relatively constant along the test-section.

The non-uniform strain distribution introduces two complications in analyzing the re-sults of the RPST experiment: a) the net force that the test-section is carrying is not simplyhalf of the load-cell reading, as in the RHTT experiment, and b) the stresses in the test-section cannot be simply assumed to be “force/area”. Both of these issues were addressedwith the aid of FEA of the RPST specimens [8].

The results can be used to plot contours of constant plastic work, shown in Figs. 7and 8. In Fig. 7, the plastic work contour is plotted in the axial-hoop plane-stress space,at constant levels of shear stress. The Yld2000-2D yield function by Barlat et al. [9]was calibrated to this data and is also included in this figure. The function captures theexperiments very accurately. To examine the evolution of the plastic work contours, thedata is plotted in the �-plane, shown in Fig. 8. Also included are the von Mises andYld2000-2D yield functions. While the former cannot capture either the anisotropy or itsevolution with plastic deformation, the latter can be calibrated to fit the experiments veryclosely.

8 C. P. Dick and Y. P. Korkolis

Fig. 7 Plane-stress yield locusof Al-6061-T4 tube, includ-ing the RPST experimentsand the Yld2000-2D materialmodel [8]

Fig. 8 Yield locus of the Al-6061-T4 tube on the �-plane,including the RPST experi-ments and the Yld2000-2Dmaterial model [8]

4 Conclusions

The RHTT and RPST experiments can be used to probe the hoop response and the yieldlocus of a tube material, respectively. The experiments require simple, general purposetesting equipment. The RHTT experiment can be used to assess the response of weldseams in ERW or porthole-die-extruded tubes. The RPST experiment provides data undertension and shear and can be used in conjunction with the tube inflation experiments toprovide a more complete picture of the tube material anisotropy.

Novel Method for Combined Tension and Shear Loading of Thin-Walled Tubes 9

5 Acknowledgement

This work was supported by the U.S. National Science Foundation under the GOALIGrant CMMI 1031169. The extruded Al-6061-T4 tubes were provided by Dr. Cedric Xiaof Ford Motor Company.

References

1. Kuwabara, T., Hashimoto, K., Iizuka, E., and Yoon, J.W., 2011, Effect of anisotropic yield func-tions on the accuracy of hole expansion simulations. J. Mat’s Processing Tech., 211, 475–481.

2. Kuwabara, T.: Biaxial Stress Testing Methods for Sheet Metals. In Comprehensive MaterialsProcessing; Van Tyne, C. J., Ed.; Elsevier Ltd., 2014; Vol. 1, pp 95–111.

3. Korkolis, Y.P. and Kyriakides, S., 2008, Inflation and burst of anisotropic aluminum tubes forhydroforming applications. Int’l J. Plasticity 24/3, 509–543.

4. Lee, M.G., Korkolis, Y.P., and Kim, J.H., 2014, Recent developments in hydroforming technol-ogy. Proc. Inst. Mech. Eng., Part B: J. Eng. Manuf., 0954405414548463.

5. Arsene, S. and Bai, J., 1996. A New Approach to Measuring Transverse Properties of StructuralTubing by a Ring Test, J. Test. & Eval. 24, 386–391.

6. Dick, C.P. and Korkolis, Y.P., 2014. Mechanics and full-field deformation study of the ring hooptension test, Int’l J. Solids & Struct, 51, 3042–3057

7. Dick, C.P. and Korkolis, Y.P., 2015, Strength and ductility evaluation of cold-welded seams inaluminum tubes extruded through porthole dies, Materials & Design, 67, 631–636

8. Dick, C.P. and Korkolis, Y.P. Anisotropy of thin-walled tubes by a new method of combinedtension and shear loading, (submitted)

9. Barlat, F., Brem, J.C., Yoon, J.W., Chung, K., Dick, R.E., Lege, D.J., Pourboghrat, F., Choi, S.-H., and Chu, E., 2003, Plane Stress Yield Function for Aluminum Alloy Sheets-Part I: Theory,Int’l J. Plasticity, 19, 1297–1319.

An Innovative Procedure for the ExperimentalDetermination of the Forming Limit Curves

Dorel Banabic, Lucian Lazarescu, and Dan-Sorin Comsa

1 Motivation

The Forming Limit Curve (FLC) is an instrument widely used for the quantitative descrip-tion of the sheet metal formability [1, 2]. Various methodologies have been proposed forthe experimental determination of the FLCs. The FLC should cover the entire deformationdomain specific to sheet metal forming processes [3]. In general, the strain combinationsspan between those induced by uniaxial and biaxial surface loads [4]. The experimen-tal methods commonly used for investigating the deformation domain of the FLCs arepresented in the following section.

The uniaxial tension of flat specimens having circular notches (proposed by Brozzoand de Lucca [5]) allows the exploration of the tension-compression range (left branchof the FLC). By using relatively wide specimens, it is also possible to reach the planestrain point. The positive-positive region (right branch) of the FLC can be reproduced in ahydraulic bulging device equipped with dies having circular or elliptic apertures. Differentload paths belonging to the tension-tension domain result by varying the eccentricity ofthe elliptic aperture [6]. Other procedures used for the experimental determination ofthe FLCs are those based on the punch stretching principle. Keeler [7] used circularspecimens and spherical punches with different radii in order to modify the load path. Ingeneral, the punch stretching test developed by Keeler is able to investigate only the rightend of the tension-tension FLC branch. Hecker [8] extended Keeler’s methodology to thewhole tension-tension domain by improving the lubrication on the contact surface betweenpunch and specimen. A notable development of this experimental procedure is due toNakazima [9]. He used a hemispherical punch having a constant radius in combinationwith rectangular specimens with different widths. In this way, Nakazima was able to

Dorel Banabic � � Lucian Lazarescu � Dan-Sorin ComsaTechnical University of Cluj-Napoca, Cluj Napoca, Romaniae-mail: banabic@tcm.utcluj.ro

11© Springer-Verlag Berlin Heidelberg 2015A. E. Tekkaya et al. (eds.), 60 Excellent Inventions in Metal Forming,DOI 10.1007/978-3-662-46312-3_2

12 D. Banabic et al.

explore both the tension-compression and the tension-tension domains of the FLC. Byusing circular specimens with lateral notches, Hasek [10] removed the main disadvantageof the Nakazima test, namely the wrinkling of wide specimens. In order to reduce thefrictional effects in the case of the flat punch drawing test, Marciniak [11] developed theso-called double blank method (specimen placed on the top of a carrier blank). He wasable to obtain different load paths by modifying the cross section of the punch (circular,elliptic or rectangular). Grosnostajski [12] improved Marciniak’s test by changing thegeometry of the specimen and carrier blank. One may notice that none of those proceduresare able to reproduce the whole strain domain of the FLC.

Therefore, an innovative procedure for the experimental determination of entire defor-mation range of the FLCs has been proposed [13]. The procedure is based on the hydraulicbulging of a double specimen.

2 New Procedure

The formability test proposed by the authors is based on the hydraulic bulging principle.It is well known the fact that, in its standard version, hydraulic bulging is only able toreproduce a biaxial tension in the polar region of the specimen. The capabilities of thistest can be extended if the specimen has a pair of holes pierced in symmetric positionswith respect to the pole. Of course, the presence of the holes creates a technical problem,namely the need of sealing the hydraulic chamber of the experimental device. The solutionof this problem consists in placing a carrier blank under the pierced specimen. The carrieracts both as a transmitter of the increasing pressure developed by the hydraulic agent anda deformable punch.

Figure 1 presents the principle of the new formability test. One may notice that thepierced specimen and the carrier blank are firmly clamped between the die and the blank

Fig. 1 Schematic view of the new formability test [13] (Copyright of Figures: Elsevier 2013)

Experimental Determination of the Forming Limit Curves 13

R35

R10

15

a

d

21 3 4 5

Ø 1

79

.8

5

Fig. 2 Strain paths obtained in the hydraulic bulge tests: comparison between the numerical simu-lation and experimental data [13] (Copyright of Figures: Elsevier 2013)

Fig. 3 Geometric parameters of the specimens [13] (Copyright of Figures: Elsevier 2013)

14 D. Banabic et al.

holder. The bulging of the specimen and carrier is caused by the increasing pressureapplied on the lower surface of the carrier. The geometric characteristics of the piercedspecimen are the dimensions and the reciprocal distance of the holes. By varying theseparameters as shown in Fig. 3, it is possible to obtain different load paths during thehydraulic bulge test and, consequently, to investigate the whole deformation range of anFLC. The methodology proposed in [13] allows determining at least five different pointson the FLC, in accordance with the specification of the standard ISO 12004-2 (see Fig. 2).

3 Results and Applications

Figure 4 compares the FLCs obtained using the methodology proposed by the authors andthe Nakazima test (according to the specifications of the international standard ISO 12004-2). In both cases, the limit strains have been measured using the ARAMIS system. Eachmeasuring point represents the mean value of three specimens. The limit strains havebeen determined according to the standard ISO 12004-2 methodology implemented inthe ARAMIS system. One may notice that the limit points obtained in the plane-straincase are almost the same for both methodologies. In the uniaxial and biaxial regions, theFLC obtained when using the new methodology is slightly translated to lower values ofthe major principal strain. This fact is in agreement with the theoretical considerationspresented in the literature (see, for example, Fig. 9.7 in [14]). Because the fracture takes

Fig. 4 Forming Limit Diagram of the AA6016-T4 sheet metal [13] (Copyright of Figure: Elsevier2013)

Experimental Determination of the Forming Limit Curves 15

place at the pole in the case of the hydraulic bulge test, the corresponding limit strains aresmaller than in the case of the hemispherical punch stretching. When the rigid punch isused (Nakazima test), the frictional interactions reduce the strain level in the polar regionand distribute the strain over a larger area. This leads to a better formability of sheet metalssubjected to hemispherical punch stretching.

4 Potential

The new method has numerous potentialities, qualifying it as a testing procedure for theFLC determination:

1. Capability of investigating the whole strain range specific to the sheet metal formingprocesses

2. Simplicity of the equipment and of the specimen configuration3. Reduction of the parasitic effects induced by the frictional interactions between the

specimen and other components of the experimental device4. Occurrence of the necking and fracture in the polar region of the specimen

5 Conclusion

An innovative procedure for the experimental determination of the FLCs has been pro-posed. The methodology is based on the hydraulic bulging of a double specimen. Theupper blank has a pair of holes pierced in symmetric positions with respect to the center,while the lower blank acts both as a carrier and a deformable punch. By modifying the di-mensions and reciprocal position of the holes, it is possible to investigate the whole strainrange specific to the sheet metal forming processes.

6 Acknowledgement

The work has been kindly supported by the Romanian National Research Council (CNCS)under the grant number PCCE 100/2009.

References

1. Banabic D., Bünge H.J., Pöhlandt K., Tekkaya A.E., 2000, Formability of Metallic Materials.Plastic Anisotropy, Formability Testing, Forming Limits, Springer, Berlin Heidelberg.

2. Banabic D., 2010, Sheet Metal Forming Processes, Springer, Berlin Heidelberg.

3. Banabic D., Barlat F., Cazacu O., Kuwabara T., 2010, Advances in anisotropy and formability,International Journal of Material Forming, 3 (2), 165–189.

16 D. Banabic et al.

4. Bruschi S., Altan T., Banabic D., Bariani P.F., Brosius A., Cao J., Ghiotti A., Khraisheh M.,Merklein M., Tekkaya E., 2014, Testing and Modeling of Material Behavior and Formability inSheet Metal Forming Processes, Annales of CIRP, 63 (1), 727–749

5. Brozzo P., de Lucca B., 1971, On the interpretation of the formability limits of metals sheets andtheir evaluation by means of elementary tests, Proc. ICSTIS, Tokyo, 966–988.

6. Ranta-Eskola A. J., 1979, Use of the hydraulic bulge test in biaxial tensile testing, InternationalJournal of Mechanical Sciences, 21 (8), 457–465.

7. Keeler S.P., 1964, Plastic instability and fracture in sheet stretched over rigid punches, Trans. ofthe ASM, (56), 25–48.

8. Hecker S. S., 1972, A simple FLC technique and results on some aluminium alloy, Proc. of the7th IDDRG Congress, Amsterdam, 51–71.

9. Nakazima K., Kikuma T., Kasuka K., 1968, Study on the formability of steel sheets, YawataTechnical Report, Nr. 264, 141–154.

10. Hasek V., 1978, Untersuchung und theoretische Beschreibung wichtiger Einflussgrossen auf dasGrenzformaenderungschaubild, Blech, 25 (5,6,10,12), 213–220, 285–292, 493–499, 619–627.

11. Marciniak Z., Kuczynski K., Pokora T., 1973, Influence of the plastic properties of material onthe FLD for sheet metal in tension, International Journal of Mechanical Sciences, 15 (10), 789–805.

12. Grosnostajski J., Dolny A., 1980, Determination of FLC by means of Marciniak punch, Mem.Sci. Rev. Met., 4, 570–576.

13. Banabic D., Lazarescu L., Paraianu L., Ciobanu I., Nicodim I., Comsa, D.S., 2013, Developmentof a new procedure for the experimental determination of the Forming Limit Curves, Annales ofCIRP, 62 (1), 255–258.

14. Marciniak Z., Duncan J.L., Hu S.J., 2002, Mechanics of Sheet Metal Forming, Butterworth-Heinemann, Oxford.

Sheet Material Characterization with the In-PlaneTorsion Test: Cyclic Loading, Grooved Specimenand Twin Bridge Specimen

Heinrich Traphöner, Qing Yin, and A. Erman Tekkaya

1 Motivation

In today’s industry the Finite-Element-Analysis (FEA) is essential for the design of partsand processes. Typical operations are the analysis of springback or failure. Due to theelastic component of the strain remaining after the forming of sheet metal components in-ternal stresses occur, which ensure that the deformed components spring back elastically,whereby the final shape of the contour differs from the tools [1]. For the description of theplastic material behavior practically often isotropic hardening models are used as the de-termination of cyclic flow curves and characteristics necessitate high experimental effort.The correct prediction of springback cannot be achieved with simple isotropic hardeningmodels, but only with isotropic-kinematic models for which the cyclic flow curves mustbe known [1]. For the determination of material parameters under cyclic load differenttests can be used. These include tension-compression tests, cyclic shear tests or cyclicbending tests [2]. Different disadvantages are connected with most of the tests. For exam-ple, bending tests have an undefined stress state [2] and tension-compression tests have tobe supported to prevent buckling under compression load [3] or the deformation zone hasto be miniaturized [4].

The in-plane torsion test and its applications for sheet metal characterization will bepresented. Beside the standard specimen that is used to measure multiple flow curves witha single specimen, two modifications of the test were introduced to measure anisotropicmaterial behavior and to characterize damage under ideal shear load.

Heinrich Traphöner � Qing Yin � A. Erman Tekkaya �TU Dortmund, Dortmund, Germanye-mail: Erman.Tekkaya@iul.tu-dortmund.de

17© Springer-Verlag Berlin Heidelberg 2015A. E. Tekkaya et al. (eds.), 60 Excellent Inventions in Metal Forming,DOI 10.1007/978-3-662-46312-3_3