Self-heating test under cyclic loading at 20kHz: determination of the heat source field

Abstract

For several years, research teams have been interested in characterizing HCF properties from self-heating tests under cyclic loadings. This method is based on two parts: the experimental characterization which deals with the temperature monitoring during cyclic loading, and a probabilistic multiscale model that enables to describe the thermomechanical behavior of the material and predict the fatigue curves.This method has been widely studied and validated at low frequency (<100Hz) on many materials. However, the application of this method to high frequency tests needs to set up a new approach to postprocess the testing results. Indeed, the particular conditions of the high frequency tests requires to consider the stress heterogeneities through the sample.An experimental protocol was therefore set up to perform self-heating tests on a high frequency machine as well as a numerical model of the test to assess different test configurations and boundary conditions. The objective of this study is to adapt the self-heating method for high frequency solicitations and to identify the thermal source through the sample with considering the mechanical field heterogeneities. This represents a crucial first step to determine the fatigue curves of different materials in the very high cycle fatigue (VHCF) domain.