FATIGUE LIFE ASSESSMENT OF HIGH-STRENGTH, LOW- … · Israel Marines-García, Damaris...

Israel Marines-Garciacutea Damaris Galvaacuten-Montiel and Claude Bathias

April 2008 The Arabian Journal for Science and Engineering Volume 33 Number 1B 237

FATIGUE LIFE ASSESSMENT OF HIGH-STRENGTH LOW-ALLOY STEEL AT HIGH FREQUENCY

Israel Marines-Garciacutea Senior Structural Integrity Engineer Tenaris-Tamsa RampD Veracruz Mexico

Damaris Galvaacuten-Montiel dagger Associate Professor CIICAp-UAEM Cuernavaca Morelos 62210 Mexico

and Claude Bathias Dagger Senior Professor CNAM-ITMA Paris 75003 France

الخالصـةدم وف نق ث -س ذا البح ي ه د - ف اد لحدي ارب اإلجه ا لتج ضه ) HSLA) D38MSV5S تقيم ن تعري ع

دورات 1010حتى ) VHCF(لدورات إجهاد عالية

ردد 35Hz و kHz 20 و ndash1 و R=01وقد أجريت تجارب اإلجهاد على نسب أحمال يس للت ه ل دنا أن فوجاقص مع 107دث اإلجهاد بعد ويمكن أن يح أثر على بيانات اإلجهاد اد بالتن دورات بحيث يتواصل تحمل اإلجهة 107 لكن اليحدث إال بعد R= ndash1ازدياد عدد الدورات بـ ة R=01 دورات في حال دنا أن ميكانيكي د وج وق

ـ ndash) VHCF(بداية التشققات مشابهة لما وجده باحثون آخرون لـ سمكة ( تعرف ب شل عين ال اء ) ف ك في أثن وذل التحليل التصويري للشقوق

Address for correspondence Dr Israel Marines - Garcia Tenaris ndash Tamsa R amp D Carr Meacutexico ndash Veracruz via Xalapa Km 4337 91697 Veracruz Ver MEXICO Tel +52 (229) 9894451 Fax +52 (229) 9891114 E-mail imarinestamsacommx dagger E-mail damarisuaemmx Dagger E-mail bathiascnamfr

Paper Received 29 March 2006 Revised 8 June 2007 Accepted 18 September 2007


The Arabian Journal for Science and Engineering Volume 33 Number 1B April 2008 238

ABSTRACT

A fatigue experimental assessment is described for an HSLA steel (high-strength low-alloy steel) D38MSV5S on very high cycle fatigue (VHCF) up to 1010 cycles The fatigue testing has been conducted at load ratio R = 01 and ndash1 under 20 kHz and 35 Hz Herein it will be observed that the test frequency does not have any effect on fatigue data The fatigue failure can occur over 107 cycles The fatigue endurance continues to decrease with an increasing number of cycles for R = ndash1 but for R = 01 no fatigue failure happened over 107 cycles Finally the same crack initiation mechanism that has been observed by other researchers on VHCF (termed fish-eye failure) has been found during our fractographic analysis

Key words gigacycle fatigue high-strength low-alloy steel high frequency testing fish-eye failures




1 INTRODUCTION

HSLA D38MSV5S steel is widely used in structural parts at the automotive industry due to its high strength characteristic However it is very well known that cyclic loading could cause structural failure at anytime Therefore it is mandatory to carry out fatigue experimentation to perform safe design of automotive components which have to survive a relatively high number of load cycles in service Bathias [1] and Baudry [2] mentioned that fatigue lifetime of some car engine components could attain 109 cycles Now considering that some components manufactured in D38MSV5S steel could reach in service the gigacycle fatigue regime the present work is focused on obtaining experimentally its fatigue behavior up to 1010 cycles However conventional fatigue machines (servo-hydraulic) are limited in testing speed this means that using those machines it could be impossible to know the experimental fatigue behavior at more than 107 cycles (eg to obtain an SndashN curve up to 1010 cycles for a single specimen it takes more than 9 years to attain such a number of cycles at 35 Hz )

In general SndashN curves are fixed at 107 cycles after that lifetime it is assumed that fatigue strength does not decrease (an assumption of asymptotic behavior is postulated) [3] but many materials do not exhibit this response instead they display a continuously decreasing stressndashlifetime response even at a great number of cycles (108 to 1010 cycles) [4ndash10] On the other hand fatigue strength within the VHCF regime is occasionally estimated by average strength σf (106 and 107 cycles) and standard deviation (s) so fatigue strength at 109 cycles is given by σf -3s [1 11] This consideration of fatigue strength estimation on VHCF range using low cycle fatigue (LCF) data is certainly not the best way to decrease the risk of fatigue failure for that reason one must carry out experimental testing to plot the fatigue behavior (SndashN curves) under VHCF for better safe fatigue design The way to do so is to use high frequency fatigue machines

Ultrasonic fatigue devices have been adopted by several research groups around the world in order to plot experimentally the SndashN curves under VHCF regime Nowadays those devices achieved a high technical standard with high accuracy and reliability [4ndash5 12ndash16] Fatigue testing on HSLA steel was possible using a high frequency device (natural resonance principle 20 kHz) Fatigue characterization was under load ratio R = 01 and ndash1 SEM analysis shows that the crack initiation on VHCF switched location from surface to an internal crack initiation Thus a hypothetical explanation related failures up to 109 cycles of biphasic steel is presented while biphasic steel is loaded on its bulk elastic regime

2 EXPERIMENTAL PROCEDURE

21 Testing Material and Specimens

The material used in this study was an HSLA steel (D38MSV5S) Its chemical composition percentage (weight) is 0384 carbon 567 silicon 123 manganese 0012 phosphorus 0064 sulfur 0183 gallium 0018 molybdenum 0063 nickel 0025 aluminum 0063 copper and 0089 vanadium The HSLA steel manufacture process was under NF EN 10267 standard Figure 1(a) shows microstructure patterns examined along two perpendicular planes longitudinal and transverse section The micrographs clearly indicate that the HSLA steel has a fine texture Ferrite (45) and pearlite (55) distribution is uniform however there are some inclusions of oxide of aluminum (Al2O3) and inclusions composed of aluminum manganese calcium and magnesium (Al2O3ndashMnOndashCaOndashMgO) Figure 1(b)

It was found that the inclusions as (Al2O3) and (Al2O3ndashMnOndashCaOndashMgO) are similar to those located on both surface and internal crack initiation Fatigue experiments were performed with loading ratio R = ndash1 and 01 The static strength values of the investigated material are shown in Table 1

Figure 2 shows the dimensions of the testing specimens The specimens have an hourglass shape with minimum diameter of 3 mm their dimensions satisfy the natural resonance (axial mode) at 20 kHz Specimens were designed by finite element method The relationship between displacements versus stress under natural resonance (vibration) was calculated using commercial computational software (ANSYS) in order to determine the testing applied stress The surface of the specimens was polished before testing in order to eliminate micro notches and to obtain a smooth surface



(a) (b)

Figure 1 HSLA steel (D38MSV5S) microstructure (a) pearlite 55 ndash ferrite 45 microstructure 500 times (b) inclusions cleanness 100 times

Table 1 Material properties of HSLA steel D38MSV5S

Ed 10kHz

(Gpa)

Ed 20 kHz

(Gpa) σy 02 (MPa)

UTS

(MPa)

A

() ρ (kgmndash3) HV30 HRc

2083 2115 608 878 20 7850 246 213

Figure 2 Shape and dimension of ultrasonic fatigue specimen

22 Test Method

Fatigue tests were performed in an open environment at room temperature using an ultrasonic fatigue test system [7 11] namely the piezoelectric (ceramic material which transforms electrical power to mechanical vibration) fatigue technique that operates at a very high frequency Using this method specimens are excited to longitudinal resonance

R31 + 001

Φ10 + 005

Φ3 + 001

6242 + 01

M5

12 L2

L1

8

L1 = 1431 mm

L2 = 169 mm

Dimensions en mm



vibrations at ultrasonic frequency (20 kHz) This leads to a sinusoidal cyclic loading with maximum load amplitude in the center of the specimen Stress amplitudes are calculated using the measured cyclic strain (strain gages) or displacement at the end of the specimen (optical fiber) The fatigue experiments were performed with constant cyclic loads with or without static preload that is load ratio R = ndash1 and 01 respectively The preload of the tensionndashtension fatigue tests (R = 01) was controlled on an INSTRON fatigue-testing machine During testing the specimen was cooled by air to decrease temperature rise caused by atomic friction (vibration) keeping the superficial temperature of the specimen between 20 and 30degC Failure of specimens may be detected by monitoring the resonance frequency which makes possible the experimentrsquos automatic operation Tests were not stopped until specimen failure occurred or cyclic loading attained 1010 cycles if failure did not happen

3 RESULTS AND DISCUSSION

31 SndashN Curves

The results of fatigue experiments on D38MSV5S steel (R = ndash1) are shown in Figure 3 specimens that did not fail are marked with an arrow lines indicate a fracture probability of 50

Test results from cyclic loading conducted at 35 Hz are between 105 and 107 cycles If the specimen did not fail at 107 cycles the testing was stopped and the result on the SndashN curve was marked as run-out International codes [3] define 107 cycles as endurance limit (hypothesis of horizontal asymptote it means that fatigue strength does not decrease any more for a given number of cycles)

Comparing experimental results from 20 kHz and 35 Hz no significant difference is observed below 107 cycles and the fatigue data coincide within the range of scatter it means that the frequency has not an influence on results On VHCF (107ndash109 cycles) it is still observed fatigue failures moreover the fatigue strength continues decreasing with the number of cycles The fatigue strength was calculated by staircase method at 106 and 1010 cycles it is 4175 and 315 MPa respectively If one estimates the safe fatigue strength value for 109 cycles given by the average strength at 106 cycles σf = 4175 MPa and the standard deviation s = 25 that is σf ndash3s then the safe fatigue strength is 3425 MPa (109cycles) Now compared to the lower experimental fatigue data the difference is close to 25 MPa Figures 3ndash4 Additional statistical analysis has been performed with the bastenaire methodology [17] Figure 5 and Table 2 The bastenaire statistical method follows the best fit of experimental results (it is not a linear regression) however the estimated curve is always finished by a horizontal asymptote Even on later observation the fatigue strength (50 failure probability) values are very close to those calculated by the staircase method

250

300

350

400

450

1E+03 1E+04 1E+05 1E+06 1E+07 1E+08 1E+09 1E+10 1E+11

N Cycles

σm

ax (M

Pa)

ITMA-CNAM 20 kHz R=-1

RENAULT 30 Hz R=-1

σ = -14963Ln(N) + 60982 R2 = 08795

Figure 3 Fatigue SndashN curve of high-strength low-alloy steel D38MSV5S with R= ndash1 20 kHz and 35 Hz




Figure 4 Fatigue stress limit comparison between estimation value and experimental results

(a) (b)

(c) (d)

Figure 5 Best fit SndashN curve and fatigue strength estimation by Bastenaire method [17] for different lifetime under load ratio

R= ndash1 (a) 1010 cycles (b) 109 cycles (c) 108 cycles and (d) 107 cycles

290

315

340

365

390

415

440

465

490

1E+03 1E+04 1E+05 1E+06 1E+07 1E+08 1E+09 1E+10NF (Cycles)

σM

AX M

Pa

290

315

340

365

390

415

440

465

490

1E+04 1E+05 1E+06 1E+07 1E+08 1E+09NF (Cycles)

σM

AX M

Pa

290

315

340

365

390

415

440

465

490

1E+04 1E+05 1E+06 1E+07 1E+08NF (Cycles)

σM

AX M

Pa

350

375

400

425

450

475

1E+03 1E+04 1E+05 1E+06 1E+07NF (Cycles)

σM

AX M

Pa10 4 10 5 108 1010 101110910710 6

N (cycles)

Fatigue stress limit

(hypothesis of the horizontal asymptote

)

55 MPa

Experimental Fatigue strength

10 4 10 5 108 1010 101110910710 610 4 10 4 10 5 10 5 108108 10101010 1011101110910910710710 610 6

N (cycles)

)

MPa


(MPa

) ∆

σ



Table 2 Fatigue Strength Estimation by Bastenaire Method [17] for Different Lifetime Under Load Ratio R= ndash1

Fatigue strength (MPa)

Lifetime (cycles) 10 failure

probability

50 failure

probability

90 failure

probability

1010 310 325 340

109 311 326 341

108 311 325 339

107 378 395 413

The experimental results under cyclic loading ratio R = 01 are shown in Figure 6 In comparison with the tensionndashcompression fatigue results the fatigue strength decreases abruptly over a short lifetime period It is noticed that the high frequency results are a little higher on strength than those of low frequency nevertheless there is a good agreement between results obtained from both high and low test frequency

There is no failure between 107 and 1010 cycles for the cyclic stress close to plastic strain in this case the hypothesis of a horizontal asymptote is valid The fatigue strength calculated at 107 cycles by the staircase method is 632 and 5725 MPa at frequencies of 35 Hz and 20 kHz respectively A high scatter in the experimental results is also observed which gives a great uncertainty Therefore those results will be treated carefully by statistics in order to carry out safe fatigue design

Figure 6 Fatigue SndashN curve of high-strength low-alloy D38MSV5S steel with R = 01 20 kHz and 35 Hz

430

480

530

580

630

680

730

780

1E+04 1E+05 1E+06 1E+07 1E+08 1E+09 1E+10 1E+11

N Cycle s

⎠7m

ax (M

Pa)

ITMA-CNAM 20 kHz

RENAULT 35 Hzσ = -33761Ln(N) + 11029R2 = 04997

σ max

(MPa

)



32 Fractography

The analysis of fracture surface under SEM shows that failures initiated on different sites (surface or internal) and from different kind of defects Fatigue crack initiation (R= ndash1) is located on surface when less than 107 cycles then it become internal (fish-eye) Figure 7 shows surface crack initiation under cyclic loading ratio R= ndash1 under maximum positive stress of 380 MPa Figure 8 shows a typical example of fish-eye pattern (internal crack initiation) which failed under maximal positive stress of 330 MPa at load ratio R= ndash1 Non-metallic inclusion was the internal crack initiator the circular area reveals fatigue crack growth until sudden final failure (unstable crack growing) However it is noticed that inclusions on most of the internal cracks were not the principal crack initiator It was the microstructure with low strength (ferrite) this can be explained as follows the specimen from a macroscopic viewpoint is loaded under lower cyclic stress amplitude (elastic zone) nevertheless from the microscopic viewpoint the ferrite grains are loaded under higher cyclic stress amplitude (plastic zone) it means that fatigue failure may occur from ferrite grain when the applied cyclic loading is higher than its strength One could conclude that ferrite grains are tested plastically (preferential crack initiation sites) even if the bulk material is tested elastically (Figure 9)

Figure 7 Surface crack initiation HSLA D38MV5S steel σmax =380 MPa Nf =942times106 R=ndash1 20KHz

Figure 8 Fatigue crack initiation from non-metallic inclusion (Al2O3+MnO+CaO+MgO) HSLA steel σmax = 330 MPa Nf =

703times107 cycles R = ndash1 20 kHz



Figure 9 Deformation behavior of two different phases for a specific applied load

Fatigue testing conducted at load ratio R = 01 does not present failure after 107 cycles crack initiation is always on the surface It means that fatigue crack initiation is strongly dependent on micro-defects and non-metallic inclusions located on the surface Also it is observed that cyclic plastic deformation in the plane stress condition becomes dangerously riskily high (σmaxσy gt 1 fully plastic testing) In Figure 10 a surface crack initiation is observed its origin is a non-metallic inclusion (Al2O3) under maximum cyclic stress of 625 MPa

Figure 10 Surface crack initiation due to non-metallic inclusion

(Al2O3) HSLA steel σmax=625 MPa Nf=204times106 cycles R = 01 20 kHz

4 CONCLUSIONS

The fatigue properties of an HSLA steel (D38MSV5S) have been investigated at two load ratios R = ndash1 and 01 under VHCF using an ultrasonic fatigue testing device (natural resonance principle) In comparison with the results obtained at a frequency of 35 Hz the fatigue properties in the regime between 105 and 1010 cycles can be summarized as follows the fatigue data for the HSLA steel between 105 and 109 cycles may be approached by a sloping line and by the Bastenaire method (best fit) between 104 and 1010 cycles in the SndashN curve with R = ndash1 Fatigue failure is still present beyond 107 cycles There is a difference of around 100 MPa between 106 and 109 cycles on experimental fatigue strength Ferrite grains and non-metallic inclusions initiated the cracks In most cases the failure initiation may switch location from surface to an interior ldquofish-eyerdquo after 107 cycles Experimental results conducted at different frequencies are in good agreement

FFaaiilluurree iinniittiiaattiioonn mmeecchhaanniissmm dduuee ttoo mmiissmmaattcchhiinngg bbeettwweeeenn ttwwoo pphhaasseess iinn tthhee mmiiccrroossttrruuccttuurree (ex FFeerrrriittee ndashndash PPeerrlliittee)

Specimen σ

ε

σx

Globally Matrix

Locally Ferrite grain

DDeeffoorrmmaattiioonn bbeehhaavviioorr ooff ttwwoo ddiiffffeerreenntt pphhaasseess ffoorr aa ggiivveenn aapppplliieedd llooaadd

F

P

P

F

F+



Fatigue strength obtained by high frequency seems to be better than at low frequency however there is still a good agreement between results However high scatter is observed it could be explained because the σmax is higher than σy (bulk material) so ferrite grains located on surface may initiate the fatigue failures (fully plasticized) No failure is observed beyond 107 cycles

A statistical analysis of experimental results may help to define the fatigue strength for a given number of cycles but it cannot be helpful in estimating fatigue strength on VHCF (safe design) Experiments must be carried out in order to explore the existence of a horizontal asymptote as mentioned in ASTM standard [3] In order to do so ultrasonic devices (natural resonance principle) have shown (former researches done by ourselves or other authors) their suitability to be used with confidence on VHCF

ACKNOWLEDGEMNT

The authors are grateful for the financial support of French companies Renault Ascometal and A2Mindustrie Thanks to them this experimental research has been possible

REFERENCES

[1] C Bathias L Drouillac and P le Franccedilois ldquoHow and Why the Fatigue SndashN Curve Does not Approach a Horizontal Asymptoterdquo International Journal of Fatigue 23 (Supplement 1) (2001) p 143

[2] Gilles Baudry Pascal Daguier Israel Marines Claude Bathias Jean-Pierre Doucet Jean-Franccedilois Vittori and Sylvain Rathery ldquoVery High Cycle (Gigacyclic) Fatigue of a Wide Range of Alternative Engineering Materials Used in Automotive Industryrdquo 3rd International Conference on Very High Cycle Fatigue (VHCF-3) Shiga and Kyoto Japan September 16-19 2004 p 298

[3] ldquoStandard Practice for Presentation of Constant Amplitude Fatigue Test Results for Metallic Materialsrdquo E468-90 (Reapproved 2004) Annual book of ASTM standards 2006 Section 3 vol 0301 pp 556ndash561

[4] QY Wang ldquoEtude de la fatigue gigacyclique des alliages ferreuxrdquo Doctoral Dissertation at Ecole Centrale de Paris 1998

[5] I Marines-Garcia G Dominguez G Baudry J-F Vittori S Rathery J-P Doucet and C Bathias ldquoUltrasonic Fatigue Tests on Bearing Steel AISI-SAE 52100 at Frequency of 20 and 30 kHzrdquo International Journal of Fatigue 25(9-11) (2003) pp 1037ndash1046

[6] I Marines-Garcia X Bin and C Bathias ldquoAn Understanding of Very High Cycle Fatigue of Metalsrdquo International Journal of Fatigue 25(9-11)(2003) pp 1101ndash1107

[7] C Bathias ldquoThere is No Infinite Fatigue Life in Metallic Materialsrdquo Fast Fract Eng Mat Struct 22(7)(1999) p 559

[8] Keisuke Tanaka Yoshiaki Akiniwa and Nobuyuki Miyamoto ldquoNotch Effect on Fatigue Strength Reduction in the Very High Cycle Regimerdquo 3rd International Conference on Very High Cycle Fatigue (VHCF-3) Shiga and Kyoto Japan September 16-19 2004 pp 56ndash67

[9] Q Y Wang H Zhang S R Sriraman and S L Liu ldquoSuper Long Life Fatigue of AE42 and AM60 Magnesium Alloysrdquo Key Engineering Materials I 306-308 (2006) pp 181ndash186

[10] Q Y Wang H Zhang M R Sriraman et al ldquoVery Long Life Fatigue Behavior of Bearing Steel AISI 52100rdquo Key Engineering Materials 297-300 (1ndash 4)(2005) pp 1846ndash1851

[11] QY Wang JY Berard A Dubarre G Baudry S Rathery and C Bathias ldquoGigacycle Fatigue of Ferrous Alloysrdquo Fatigue Fract Engng Mater Struct 22(8)(1999) p 667

[12] C Bathias ldquoAutomated Piezoelectric Fatigue Machine for Severe Environmentsrdquo ASTM STP 2002 1411 pp 3ndash15

[13] Z D Sun C Bathias and G Baudry ldquoFretting Fatigue of 42CrMo4 Steel at Ultrasonic Frequencyrdquo International Journal of Fatigue 23(5)(2001) p 449ndash450

[14] S E Stanzl-Tschegg H R Mayer and E K Tschegg ldquoHigh Frequency Method for Torsion Fatigue Testingrdquo Ultrasonic 31(4)(1993) pp 598ndash607



[15] T Wu J Ni and C Bathias ldquoAn Automatic Ultrasonic Fatigue Testing System for Studying Low Crack Growth at Room and High Temperaturesrdquo ASTM STP 1231 (1994) p 598ndash607

[16] Israel Marines-Garcia Jean-Pierre Doucet and Claude Bathias ldquoDevelopment of a New Device to Perform Torsional Ultrasonic Fatigue Testingrdquo International Journal of Fatigue 29(9ndash11)(2007) pp 2094ndash2101

[17] F Bastenaires ldquoEstimation et Prevision Statistiques de la Resistance et de la Dureacutee des Mateacuteriaux en Fatiguerdquo IRSID report



ABSTRACT

A fatigue experimental assessment is described for an HSLA steel (high-strength low-alloy steel) D38MSV5S on very high cycle fatigue (VHCF) up to 1010 cycles The fatigue testing has been conducted at load ratio R = 01 and ndash1 under 20 kHz and 35 Hz Herein it will be observed that the test frequency does not have any effect on fatigue data The fatigue failure can occur over 107 cycles The fatigue endurance continues to decrease with an increasing number of cycles for R = ndash1 but for R = 01 no fatigue failure happened over 107 cycles Finally the same crack initiation mechanism that has been observed by other researchers on VHCF (termed fish-eye failure) has been found during our fractographic analysis

Key words gigacycle fatigue high-strength low-alloy steel high frequency testing fish-eye failures




1 INTRODUCTION











(a) (b)



Ed 10kHz

(Gpa)

Ed 20 kHz

(Gpa) σy 02 (MPa)

UTS

(MPa)

A


2083 2115 608 878 20 7850 246 213


22 Test Method


R31 + 001

Φ10 + 005

Φ3 + 001

6242 + 01

M5

12 L2

L1

8

L1 = 1431 mm

L2 = 169 mm

Dimensions en mm





31 SndashN Curves




250

300

350

400

450

1E+03 1E+04 1E+05 1E+06 1E+07 1E+08 1E+09 1E+10 1E+11

N Cycles

σm

ax (M

Pa)


RENAULT 30 Hz R=-1

σ = -14963Ln(N) + 60982 R2 = 08795






(a) (b)

(c) (d)



290

315

340

365

390

415

440

465

490


σM

AX M

Pa

290

315

340

365

390

415

440

465

490

1E+04 1E+05 1E+06 1E+07 1E+08 1E+09NF (Cycles)

σM

AX M

Pa

290

315

340

365

390

415

440

465

490

1E+04 1E+05 1E+06 1E+07 1E+08NF (Cycles)

σM

AX M

Pa

350

375

400

425

450

475

1E+03 1E+04 1E+05 1E+06 1E+07NF (Cycles)

σM

AX M

Pa10 4 10 5 108 1010 101110910710 6

N (cycles)



)

55 MPa


10 4 10 5 108 1010 101110910710 610 4 10 4 10 5 10 5 108108 10101010 1011101110910910710710 610 6

N (cycles)

)

MPa


(MPa

) ∆

σ






probability

50 failure

probability

90 failure

probability

1010 310 325 340

109 311 326 341

108 311 325 339

107 378 395 413




430

480

530

580

630

680

730

780

1E+04 1E+05 1E+06 1E+07 1E+08 1E+09 1E+10 1E+11

N Cycle s

⎠7m

ax (M

Pa)

ITMA-CNAM 20 kHz

RENAULT 35 Hzσ = -33761Ln(N) + 11029R2 = 04997

σ max

(MPa

)



32 Fractography











4 CONCLUSIONS



Specimen σ

ε

σx

Globally Matrix



F

P

P

F

F+





ACKNOWLEDGEMNT


REFERENCES























1 INTRODUCTION











(a) (b)



Ed 10kHz

(Gpa)

Ed 20 kHz

(Gpa) σy 02 (MPa)

UTS

(MPa)

A


2083 2115 608 878 20 7850 246 213


22 Test Method


R31 + 001

Φ10 + 005

Φ3 + 001

6242 + 01

M5

12 L2

L1

8

L1 = 1431 mm

L2 = 169 mm

Dimensions en mm





31 SndashN Curves




250

300

350

400

450

1E+03 1E+04 1E+05 1E+06 1E+07 1E+08 1E+09 1E+10 1E+11

N Cycles

σm

ax (M

Pa)


RENAULT 30 Hz R=-1

σ = -14963Ln(N) + 60982 R2 = 08795






(a) (b)

(c) (d)



290

315

340

365

390

415

440

465

490


σM

AX M

Pa

290

315

340

365

390

415

440

465

490

1E+04 1E+05 1E+06 1E+07 1E+08 1E+09NF (Cycles)

σM

AX M

Pa

290

315

340

365

390

415

440

465

490

1E+04 1E+05 1E+06 1E+07 1E+08NF (Cycles)

σM

AX M

Pa

350

375

400

425

450

475

1E+03 1E+04 1E+05 1E+06 1E+07NF (Cycles)

σM

AX M

Pa10 4 10 5 108 1010 101110910710 6

N (cycles)



)

55 MPa


10 4 10 5 108 1010 101110910710 610 4 10 4 10 5 10 5 108108 10101010 1011101110910910710710 610 6

N (cycles)

)

MPa


(MPa

) ∆

σ






probability

50 failure

probability

90 failure

probability

1010 310 325 340

109 311 326 341

108 311 325 339

107 378 395 413




430

480

530

580

630

680

730

780

1E+04 1E+05 1E+06 1E+07 1E+08 1E+09 1E+10 1E+11

N Cycle s

⎠7m

ax (M

Pa)

ITMA-CNAM 20 kHz

RENAULT 35 Hzσ = -33761Ln(N) + 11029R2 = 04997

σ max

(MPa

)



32 Fractography











4 CONCLUSIONS



Specimen σ

ε

σx

Globally Matrix



F

P

P

F

F+





ACKNOWLEDGEMNT


REFERENCES






















(a) (b)



Ed 10kHz

(Gpa)

Ed 20 kHz

(Gpa) σy 02 (MPa)

UTS

(MPa)

A


2083 2115 608 878 20 7850 246 213


22 Test Method


R31 + 001

Φ10 + 005

Φ3 + 001

6242 + 01

M5

12 L2

L1

8

L1 = 1431 mm

L2 = 169 mm

Dimensions en mm





31 SndashN Curves




250

300

350

400

450

1E+03 1E+04 1E+05 1E+06 1E+07 1E+08 1E+09 1E+10 1E+11

N Cycles

σm

ax (M

Pa)


RENAULT 30 Hz R=-1

σ = -14963Ln(N) + 60982 R2 = 08795






(a) (b)

(c) (d)



290

315

340

365

390

415

440

465

490


σM

AX M

Pa

290

315

340

365

390

415

440

465

490

1E+04 1E+05 1E+06 1E+07 1E+08 1E+09NF (Cycles)

σM

AX M

Pa

290

315

340

365

390

415

440

465

490

1E+04 1E+05 1E+06 1E+07 1E+08NF (Cycles)

σM

AX M

Pa

350

375

400

425

450

475

1E+03 1E+04 1E+05 1E+06 1E+07NF (Cycles)

σM

AX M

Pa10 4 10 5 108 1010 101110910710 6

N (cycles)



)

55 MPa


10 4 10 5 108 1010 101110910710 610 4 10 4 10 5 10 5 108108 10101010 1011101110910910710710 610 6

N (cycles)

)

MPa


(MPa

) ∆

σ






probability

50 failure

probability

90 failure

probability

1010 310 325 340

109 311 326 341

108 311 325 339

107 378 395 413




430

480

530

580

630

680

730

780

1E+04 1E+05 1E+06 1E+07 1E+08 1E+09 1E+10 1E+11

N Cycle s

⎠7m

ax (M

Pa)

ITMA-CNAM 20 kHz

RENAULT 35 Hzσ = -33761Ln(N) + 11029R2 = 04997

σ max

(MPa

)



32 Fractography











4 CONCLUSIONS



Specimen σ

ε

σx

Globally Matrix



F

P

P

F

F+





ACKNOWLEDGEMNT


REFERENCES
























31 SndashN Curves




250

300

350

400

450

1E+03 1E+04 1E+05 1E+06 1E+07 1E+08 1E+09 1E+10 1E+11

N Cycles

σm

ax (M

Pa)


RENAULT 30 Hz R=-1

σ = -14963Ln(N) + 60982 R2 = 08795






(a) (b)

(c) (d)



290

315

340

365

390

415

440

465

490


σM

AX M

Pa

290

315

340

365

390

415

440

465

490

1E+04 1E+05 1E+06 1E+07 1E+08 1E+09NF (Cycles)

σM

AX M

Pa

290

315

340

365

390

415

440

465

490

1E+04 1E+05 1E+06 1E+07 1E+08NF (Cycles)

σM

AX M

Pa

350

375

400

425

450

475

1E+03 1E+04 1E+05 1E+06 1E+07NF (Cycles)

σM

AX M

Pa10 4 10 5 108 1010 101110910710 6

N (cycles)



)

55 MPa


10 4 10 5 108 1010 101110910710 610 4 10 4 10 5 10 5 108108 10101010 1011101110910910710710 610 6

N (cycles)

)

MPa


(MPa

) ∆

σ






probability

50 failure

probability

90 failure

probability

1010 310 325 340

109 311 326 341

108 311 325 339

107 378 395 413




430

480

530

580

630

680

730

780

1E+04 1E+05 1E+06 1E+07 1E+08 1E+09 1E+10 1E+11

N Cycle s

⎠7m

ax (M

Pa)

ITMA-CNAM 20 kHz

RENAULT 35 Hzσ = -33761Ln(N) + 11029R2 = 04997

σ max

(MPa

)



32 Fractography











4 CONCLUSIONS



Specimen σ

ε

σx

Globally Matrix



F

P

P

F

F+





ACKNOWLEDGEMNT


REFERENCES
























(a) (b)

(c) (d)



290

315

340

365

390

415

440

465

490


σM

AX M

Pa

290

315

340

365

390

415

440

465

490

1E+04 1E+05 1E+06 1E+07 1E+08 1E+09NF (Cycles)

σM

AX M

Pa

290

315

340

365

390

415

440

465

490

1E+04 1E+05 1E+06 1E+07 1E+08NF (Cycles)

σM

AX M

Pa

350

375

400

425

450

475

1E+03 1E+04 1E+05 1E+06 1E+07NF (Cycles)

σM

AX M

Pa10 4 10 5 108 1010 101110910710 6

N (cycles)



)

55 MPa


10 4 10 5 108 1010 101110910710 610 4 10 4 10 5 10 5 108108 10101010 1011101110910910710710 610 6

N (cycles)

)

MPa


(MPa

) ∆

σ






probability

50 failure

probability

90 failure

probability

1010 310 325 340

109 311 326 341

108 311 325 339

107 378 395 413




430

480

530

580

630

680

730

780

1E+04 1E+05 1E+06 1E+07 1E+08 1E+09 1E+10 1E+11

N Cycle s

⎠7m

ax (M

Pa)

ITMA-CNAM 20 kHz

RENAULT 35 Hzσ = -33761Ln(N) + 11029R2 = 04997

σ max

(MPa

)



32 Fractography











4 CONCLUSIONS



Specimen σ

ε

σx

Globally Matrix



F

P

P

F

F+





ACKNOWLEDGEMNT


REFERENCES

























probability

50 failure

probability

90 failure

probability

1010 310 325 340

109 311 326 341

108 311 325 339

107 378 395 413




430

480

530

580

630

680

730

780

1E+04 1E+05 1E+06 1E+07 1E+08 1E+09 1E+10 1E+11

N Cycle s

⎠7m

ax (M

Pa)

ITMA-CNAM 20 kHz

RENAULT 35 Hzσ = -33761Ln(N) + 11029R2 = 04997

σ max

(MPa

)



32 Fractography











4 CONCLUSIONS



Specimen σ

ε

σx

Globally Matrix



F

P

P

F

F+





ACKNOWLEDGEMNT


REFERENCES






















32 Fractography











4 CONCLUSIONS



Specimen σ

ε

σx

Globally Matrix



F

P

P

F

F+





ACKNOWLEDGEMNT


REFERENCES


























4 CONCLUSIONS



Specimen σ

ε

σx

Globally Matrix



F

P

P

F

F+





ACKNOWLEDGEMNT


REFERENCES
























ACKNOWLEDGEMNT


REFERENCES




















FATIGUE LIFE ASSESSMENT OF HIGH-STRENGTH, LOW- … · Israel Marines-García, Damaris...

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Transcript of FATIGUE LIFE ASSESSMENT OF HIGH-STRENGTH, LOW- … · Israel Marines-García, Damaris...