Slip deformation and temperature variation of a single crystal metallic material associated with cyclic loading

Abstract

Rapid evaluation of fatigue limit using infrared camera is beneficial because it also makes possible to detect the location of fatigue damage in actual structures. However, the physical background and validity of this method have not been fully investigated. It is required to clarify the relationship between fatigue damage and temperature variation. In this study, observation of slip deformation and measurement of temperature by infrared camera are conducted to notched specimens of single crystal metallic material associated with cyclic loading. First, cyclic loadings, which are below and beyond the fatigue limit, are applied to the specimen in order to investigate the factors that generate dissipated energy at below and beyond the fatigue limit. Experimental results show that dissipated energy is generated by internal friction below the fatigue limit and by fatigue damage beyond the fatigue limit. Finally, a similar experiment is conducted to the specimens with different crystal orientation. The result shows that the slip location is affected by the crystal orientation due to the orientation-dependent stress distribution and the dissipated energy distribution.