Influence of residual plastic strain on the thermoelastic behavior of a titanium alloy

摘要

The thermoelastic effect that manifests as a change in temperature of a body undergoing adiabatic elastic deformation has been utilized for full-field stress analysis in solids using the infrared thermal imaging technique. This technique has been used for nondestructive evaluation of residual stresses in components. The present study endeavors to examine the effect of residual plastic strain, due to a previously imposed plastic deformation, on the thermoelastic behavior of solids. Near-alpha titanium alloy specimens have been plastically deformed, and after reaching a plastic strain level, the test has been interrupted. The thermoelastic response of the interrupted specimens has been examined. The infrared thermal imaging technique has been used to capture the spatiotemporal evolution of the surface temperature of the specimens. It has been observed that the thermoelastic coefficient of the alloy increases as a function of prior/residual plastic strain for small deformations. It has been shown that the theoretical framework used to explain the effect of residual stress on the thermoelastic coefficient assuming a perfect crystal lattice is not applicable to explain the effect of residual plastic strain on the thermoelastic coefficient. A modification of the existing theory has been proposed to explain the dependence of the thermoelastic coefficient on the residual plastic strain. A thermodynamic framework considering the local entropy and internal energy density has been developed to study the behavior. The microscopic aspects of the energetic of thermoelasticity have been discussed and based on this a continuum dislocation dynamic model has been proposed to explain the variation in the thermoelastic coefficient. Published under license by AIP Publishing.