Investigations into Gas-Pore Effects on Fatigue Strength with a Peridynamic Approach

Abstract

Fatigue evaluations are one of the main challenges to applying additively manufactured primary structural elements onto aircraft, especially for the gas-pore effects on fatigue strength. In this work, a bond decomposition strategy (BDS) in peridynamics (PD) is proposed; combined with our previously proposed model for fatigue damage, numerical simulations were performed to study the effect of Gas Pore (GP) on fatigue strength. Compared with the strategies in original paradigm of peridynamics, BDS achieves more elaborate description for bond status, predicts deformation fields around discontinuities with improved accuracy, and makes the spacing of material points become independent of discontinuity geometries. Two initiation modes are found in PD simulations, which exert an obvious impact on the final fatigue lifetimes; furthermore, it is revealed that GP not only leads to lower fatigue strength but also results in dispersity of fatigue strength data, in which dispersity is more severe if the GP size is larger, and the decline of fatigue strength is the most severe if the GP is located at subsurface for the same GP size.

Keywords

• fatigue strength
• additive manufacturing
• peridynamics
• multiscale modeling