Correlation between thermography and internal damping in metals

Abstract The object of this paper is an investigation of the relationship existing between two experimental techniques, both aimed at the assessment of micro-plastic phenomena and micro-friction inside a material: thermographic analysis and specific damping measurement. A model has been developed here considering the main thermal effects during fatigue tests, and a theoretical relationship between temperature increment and specific damping has been proposed. Successively, an extensive experimentation has been carried on groups of specimens made of two different metals, stressed by means of an Amsler vibrophore. Different stress amplitudes (80–270 MPa) and frequencies (80–160 Hz) have been employed. The analysis of experimental results has allowed the validation of the suggested model, leading, on one side, to the development of a further experimental technique for the evaluation of specific damping, and, on the other side, to the employment of specific damping measurement for the assessment of fatigue in metals.