Frequency dependent deformation reversibility during cyclic loading

Abstract

High-frequency testing (HFT) is useful for accelerated fatigue testing of conventional materials that typically serve under low-frequency loading conditions, as well as for the assessment of the robustness of microelectromechanical systems which typically experience high-frequency service conditions. Using discrete dislocation dynamics, we attempt to elucidate the effect of loading frequency on the reversibility of cyclic deformation. We demonstrate that the HFT induces a higher fraction of reversible cyclic deformation because of a larger portion of elastic/anelastic deformation due to limited dislocation mobility, and a higher degree of reversibility in plastic deformation owing to the less occurrence of cross-slip. (Image presented) IMPACT STATEMENT Dislocation-based frequency effects on high-cycle deformation reversibility in metals are elucidated. Hysteresis energy is shown to dissipate even under ideal, damage-free conditions, contrary to popular assumptions of energy-based fatigue models.