Calorimetric analysis of dissipative and thermoelastic effects associated with the fatigue behavior of steels

The fatigue of dual phase steel was examined in terms of calorimetric effects in order to match the energy manifestations offatigue and constitutive equations drawn up in a thermomechanical framework. A simplified method, assuming a homogeneousfatigue test, is proposed to determine heat source development from a temperature field provided by an infrared camera. Thermoelas-tic and dissipative sources were then separately identified. Experimental results concerning thermoelastic effects are in close agree-ment with theoretical estimates. Dissipation depends on the loading frequency and stress amplitude applied to the fatigue specimen.However, as the marked decrease in dissipation observed when testing a block at high stress was not easily interpretable in termsof material effects, we questioned the homogeneous fatigue test assumption.