Thermoelastic and Elastoplastic Effects Measured by Means of a Standard Thermocamera

It is well known that a metallic specimen changes its temperature when it is subjected to cyclic stresses. If the strain is elastic, the temperature change is produced by two main effects: elastoplasticity and thermoelasticity. The first phenomenon is due to microplasticity and energy dissipation inside a material that causes the conversion of mechanical energy into heat. Thermoelasticity can be explained through the first thermodynamic law, according to which volume increase is associated to temperature decrease in adiabatic conditions, and vice versa. Thermoelasticity and elastoplasticity produce very different temperature patterns. The first one induces a periodic temperature change, synchronous with loading history and proportional to the actual load amplitude. 1 The thermoplasticity produces a continuous temperature increment, related to both load amplitude and the number off performed cycles until thermal equilibrium is reached.