Abstract
It is well known that materials subjected to cyclic loads increase their temperatures, either by elastic or much more intensely by plastic straining mechanisms. Because fatigue damage is a dissipative process associated with cyclic plastic strains, such temperature increments are much larger for loads above the fatigue limit than below it. Since standard techniques to measure fatigue limits are too laborious, even the accelerated ones like Dixon’s up-and-down method, due to the very longtime required to run the tests, La Rosa and Risitano proposed a quick thermographic approach to measure fatigue limits based on temperature increments observed during fatigue tests. This method works very well for steels, but not so well for Al alloys, albeit they would be even more useful for them, whose fatigue limits are associated with a much larger number of cycles than the steels. This work investigates the limitations of the thermographic method when it is used to evaluate an Al 6351-T6 alloy fatigue limit, and of the alternative method of extrapolating its measured εN curve to very long lives. In addition, alternative ways to obtain a better fatigue limit estimate based on thermal data are discussed.
Similar content being viewed by others
Abbreviations
- S :
-
Stress (MPa)
- S L * :
-
Fatigue limit of component (MPa)
- S L :
-
Fatigue limit of material (MPa)
- S U :
-
Ultimate strength (MPa)
- k sf :
-
Surface treatment factor
- k sz :
-
Size factor
- k lt :
-
Load type factor
- k θ :
-
Working temperature factor
- k ri :
-
Reliability factor
- k ft :
-
Fretting factor
- N :
-
Life (in number of cycles)
- N L :
-
Life at fatigue limit (in number of cycles)
- θ :
-
Maximum temperature (°C)
- θ i :
-
Maximum temperature of phase i (°C)
- Δθ i :
-
Maximum temperature variation of phase i (°C)
- ΔN :
-
Variation of number of cycles (N)
- N i :
-
Number of cycles of phase i (N)
- σ a :
-
Alternate stress (MPa)
- σ c :
-
Coffin–Manson’s elastic coefficient (MPa)
- ε a :
-
Alternate strain (–)
- ε c :
-
Coffin–Manson’s plastic coefficient (–)
- Δε pl :
-
Plastic component of the strain range (–)
- Δε el :
-
Elastic component of the strain range (–)
- C :
-
Wöhler’s constant (–)
- B :
-
Wöhler’s exponent (–)
- E :
-
Elasticity (or Young’s) modulus in tension (GPa)
- h c :
-
Cyclic strain-hardening exponent (–)
- f :
-
Frequency (Hz)
- R a :
-
Roughness (µm)
- R :
-
Stress ratio σmin/σmax (–)
- S LR _ SP1 :
-
Risitano’s fatigue limit of first specimen (MPa)
- S LR_SP2 :
-
Risitano’s fatigue limit of second specimen (MPa)
- S LR :
-
Average Risitano’s fatigue limit (MPa)
- b :
-
Coffin–Manson’s elastic exponent
- c :
-
Coffin–Manson’s plastic exponent
- S LE :
-
N extrapolation’s fatigue limit (MPa)
- S LA1 :
-
First alternative thermographic fatigue limit (MPa)
- S LA2_SP1 :
-
Second alternative thermographic fatigue limit for the first specimen (MPa)
- S LA2_SP2 :
-
Second alternative thermographic fatigue limit for the second specimen (MPa)
- S LA2 :
-
Average second alternative thermographic method’s fatigue limit (MPa)
- R 2 :
-
Coefficient of determination (–)
- S LL :
-
Literature’s fatigue limit (MPa)
References
Castro JTP, Meggiolaro MA (2016) Fatigue design techniques, v.2: low-cycle and multiaxial fatigue. CreateSpace.
Prot EM (1948) Fatigue testing under progressive loading, a new technique for testing materials. Revue de Metall 45:481
Dixon WJ (1965) The up-and-down method for small samples. Am Stat Assoc J 60:967–978
Castro JTP, Meggiolaro MA (2016) Fatigue design techniques, v.1: High-cycle fatigue. CreateSpace.
Marin J (1962) Mechanical behavior of engineering materials. Prentice-Hall, Bacon Raton
Haibach E (1970) Modified linear damage accumulation hypothesis accounting for a decreasing fatigue strength during increasing fatigue damage, LBF TM Nr.50, Darmstadt, Germany.
Madhukar S et al (2018) A study on improvement of fatigue life of materials by surface coatings
Bandeira CFB, Kenedi PP, Castro JTP (2018) On the use of thermographic method to measure fatigue limits. Latin Am J Solids Struct 15:e60
La Rosa G, Risitano A (1999) Thermographic methodology for the rapid determination of the fatigue limit of materials and mechanical components. Int J Fatigue Mater Struct Components 22:65–73
Fargione G, Gerarci A, La Rosa G, Risitano A (2002) A rapid determination of the fatigue curve by the thermographic method. Int J Fatigue 24:11–19
Lipski A (2016) Accelerated determination of the fatigue limit and the S-N curve by means of the thermographic method for X5CrNi18-10 steel. Acta Mech et Automat 10:22–27
Bandeira CFB, Kenedi PP, Castro JTP (2017) Thermography: a faster method to obtain the fatigue or endurance limit of materials. In: International symposium on solid mechanics, 6th Edition.
Bandeira CFB, Kenedi PP, Castro JTP, Meggiolaro MA (2017) On the use of the thermographic technique to determine the fatigue limit of a cold drawn carbon steel. In: 7th International conference on very high cycle fatigue, pp 329–334, U. Siegen.
Curà F, Curti G, Sesana R (2005) A new iteration method for the thermographic determination of fatigue limit in steels. Int J Fatigue 27(4):453–459
Li XD et al (2012) Adopting lock-in infrared thermography technique for rapid determination of fatigue limit of aluminum alloy riveted component and affection to determined result caused by initial stress. Int J Fatigue 36(1):18–23
Zhang L et al (2013) Rapid determination of fatigue life based on temperature evolution. Int J Fatigue 54:1–6
Morabito AE, Chrysochoos A, Dattoma V, Galietti U (2007) Analysis of heat sources accompanying the fatigue of 2024 T3 aluminium alloys. Int J Fatigue 29:977–984
De Finis R, Palumbo D, Silva MM, Galietti U (2017) Is the temperature plateau of a self-heating test a robust parameter to investigate the fatigue limit of steels with thermography? Fatigue Fract Eng Mater Struct 10:1331
Meneghetti G (2007) Analysis of the fatigue strength of a stainless steel based on the energy dissipation. Int J Fatigue 29:81–94
De Finis R, Palumbo D, Serio LM, De Filippis LAC, Galietti U (2018) Correlation between thermal behaviour of AA5754-H111 during fatigue loading and fatigue strength at fixed number of cycles. Materials 11(5):719
DuQuesnay DL, Topper TH, Yu MT, Pompetzki MA (1992) The effective stress range as a mean stress parameter. Int J Fatigue 14:45–50
DuQuesnay DL, Pompetzki MA, Topper TH (1993) Fatigue life predictions for variable amplitude strain histories. SAE Trans 5:102
Castillo E, Fernández-Canteli A, Pinto H, López-Aenlle M (2008) A general regression model for statistical analysis of strain-life data. Mater Lett D 62:3639–3642
Fernández-Canteli A, Castillo E, Argüelles A, Fernández P, Canales M (2012) Checking the fatigue limit from thermographic techniques by means of a probabilistic model of the epsilon-N field. Int J Fatigue 39:109–115
Alarcón MVG, Castro JTP, Vieira RB, Paiva VEL, Freire JLF (2017) Fatigue limit assessment of a low carbon steel using Dixon’s up-and-down and infrared thermography methods. In: 12th international conference on advances Exp Mech, U Sheffield, UK.
Juvinall RC (1967) Stress. McGraw-Hill, Strain and Strength
Seitl S et al (2013) Comparison of analysis methods of data from thermographic measurements of Al 2024 fatigue limit for R = 0.1. Transactions of the VŠB – Technical University of Ostrava, Mechanical Series; No. 2, vol LIX
Acknowledgements
Authors acknowledge the financial support from CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior) and the effort devoted by reviewers to improving the quality of this article.
Author information
Authors and Affiliations
Corresponding author
Additional information
Technical Editor: João Marciano Laredo dos Reis.
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
About this article
Cite this article
Martins, G.C.P., Bandeira, C.F.C., Lima, G.W. et al. Fatigue limit evaluations of Al 6351-T6 by thermographic and εN methods. J Braz. Soc. Mech. Sci. Eng. 43, 11 (2021). https://doi.org/10.1007/s40430-020-02758-9
Received:
Accepted:
Published:
DOI: https://doi.org/10.1007/s40430-020-02758-9