On the correlation of temperature harmonic content with energy dissipation in C45 steel samples under fatigue loading

Fatigue damage onset involves a transformation of mechanical energy. This is in part spent into work plastic deformation and fracture transformed heat. Therefore, different thermomechanical heat sources are activated during fatigue loading cycle, resulting temperature modulation that can be characterized by its frequency content. Several studies have monitored the on samples undergoing high-cycle fatigue, measuring specific metrics which could serve as indicators evolution. The present evaluates harmonic content temperature, to investigate correlation with material dissipation. terms investigated amplitude phase at (First Harmonic) twice (Second Harmonic). paper reviews mechanisms linking evolution dissipation changes these four parameters. theoretical analysis supported an experimental campaign carried out C45 steel tensile specimen subject R=?1 R=0.1 ratios. evaluated analyzing both their spatially averaged value spatial dispersion, check for formation localized zones early life. study shows Second Harmonic signal has peculiar bimodal distribution correlated either thermoelastic or dissipative prevailing effect. behavior evolves towards unimodal when load increased, thus proposing parameter effective indicator monitoring internal intrinsic material.