Fatigue life prediction for structure under fatigue and low-energy impact based on continuum damage mechanics

Abstract

A product characterized by fatigue-induced failure is subjected to complex cyclic load which cause fatigue damage accumulated over time. At the same time, the product under cyclic load may suffer from low-energy impact during the whole service life. For its discontinuity, the low-energy impact does not lead to the product failure immediately. The low-energy impact not only cause structural damage and the residual strength degradation instantly but also influence the effect of cyclic load. And cyclic load has the same effect for structural in return. This article shows an approach for fatigue life prediction based on continuum damage mechanics with coupling relationship between fatigue damage and impact damage. First, the features and coupling relationships of fatigue damage and impact damage are discussed in this essay and both of them result in a drop in residual strength of structure. Second, the initial stress response under impact and fatigue loads were obtained. The existed evolution equations of fatigue and impact damage were respectively introduced. Third, based on these damage evolution equations, a new coupling damage model for fatigue damage and impact damage has been established and the damage and residual strength evolution of the structure is proposed. Finally, an engineering case is introduced to validate the approach.