Thermomechanical Phenomenon: A Non-destructive Evaluation Perspective
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When subjected to continuous tensile loads, a material cools in the elastic regime and heats up in the plastic regime. Temperature changes are also observed when metals are subjected to cyclic stresses of amplitude below the yield strength. The insights into the use of thermomechanical phenomenon as a NDE technique are presented here based on experimental and computational evidence. Infrared thermal camera has been used to monitor the temperature changes in the materials. Measured temperature changes for tensile load on a material subjected to different levels of plastic deformation and for cyclic load on material are presented. Existing theoretical basis to explain the thermomechanical response is discussed in terms of (a) thermoelastic effect for the elastic regime in tensile load, (b) Taylor–Quinney coefficient for the plastic regime in tensile load, and (c) phenomenological models for the cyclic load. For the case of monotonic tensile loading, the extent of initial plastic deformation of a material is experimentally correlated with the observed decrease in temperature in the elastic regime. For the case of cyclic loading leading to stresses below the yield strength, the Kelvin–Voigt model has been found to be sufficient to explain the temperature changes. Amount of plastic deformation accumulated in the material can be deduced based on the decrease in temperature during tensile loading. Closeness between the parameters of Kelvin–Voigt model and that of the grain make this model suitable for understanding the thermomechanical response of polycrystalline materials subjected to stresses below the yield strength. To fully explain the thermoplastic effect beyond the Taylor–Quinney coefficient, a phenomenological model that accounts for the grain resizing, along with rotation and sliding, during the plastic deformation needs to be developed.
KeywordsThermoelasticity Internal heat Plastic regime Grain boundaries Grain boundary sliding
We thank Pravin Patil and Dr. Kathirvel Thiyagarjan for their contributions in major experimental aspects of this work.
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Conflict of interest
The authors declare that they have no conflict of interest.
- 1.NDT resource. Available from: https://www.asnt.org/MinorSiteSections/AboutASNT/Intro-to-NDT [Accessed: 2018-01-07].
- 3.Maldague X, Theory and practice of infrared technology for nondestructive testing, 1st ed, Wiley, New York (2001), p 684.Google Scholar
- 7.Pieczyska E, J Theor Appl Fract Mech 37 (1999) 349.Google Scholar
- 10.Patil P, Thiyagarajan K, Prakash R, Balasubramaniam K, Int J Adv Manuf Technol (2009). https://doi.org/10.1007/s00170-008-1870-1.
- 16.Patil P, Fatigue Damage Characterization in a Stainless Steel Using Infrared Thermography, M. Tech Thesis, Indian Institute of Technology Madras, India (2010).Google Scholar
- 17.Thiyagarajan K, Application of Infrared Thermographic Technique to Plastic Deformation Studies, Ph D Thesis, Indian Institute of Technology Madras, India (2010).Google Scholar
- 18.Thyiagarajan K, Prakash R, and Balasubramaniam K, in Proceedings of the 11th International Conference on Quantitative InfraRed Thermography QIRT-2012-253 (2012) June, Naples, Italy.Google Scholar
- 26.Norton R L, Machine Design: An integrated approach, Pearson Education Inc, London (2000), p 1078.Google Scholar
- 33.Boley B, and Weiner J, Theory of Thermal Stresses, Wiley, London (1962), p 608.Google Scholar
- 42.ASTM standards. Available from http://www.trl.com/astm_e8_tensile_testing_of_metals/ [Accessed 2018-01-14].
- 43.Carslaw H, and Jaeger J, Conduction of Heat in Solids, Clarendon Press, Oxford (1947), p 540.Google Scholar