A Numerical Investigation of Heat Generation Due to Dissipation in Ultrasonic Fatigue Testing of 42CrMo4 Steel Employing Thermography Data

In ultrasonic fatigue testing of steels one can observe rapid local heating due to crack initiation and propagation caused by non-metallic inclusions and in addition also an overall heating of the gauge length portion of samples which is attributed to dissipational effects. The computations performed in this study are based on a three-dimensional, fully-coupled linear thermoelastic continuum model, where dissipation is included by employing a volumetric heat source. In the numerical computation the temperature distribution evolution in the geometry of interest is the result of a combination of initial conditions, boundary conditions and the heat source contribution. The heat source function's geometry and intensity are deduced by comparing computed temperature profiles to data obtained experimentally using a thermo-camera. It turns out that the modeling approach, making extensive use of thermography data, yields computational results that are in agreement with the experimental heat evolution, and additionally the amount of heat generated is in agreement with results found in literature.