Computational homogenization of fatigue in additively manufactured microlattice structures

Abstract

A novel computational approach to predicting fatigue crack initiation life in additively manufactured microlattice structures is proposed based on a recently developed microplasticity-based constitutive theory. The key idea is to use the concept of (micro)plastic dissipation as the driving factor to model fatigue degradation in additively manufactured metallic microlattice. An ad-hoc curve-fitting procedure is proposed to calibrate the introduced material constitutive parameters efficiently. The well-calibrated model is employed to obtain fatigue life predictions for microlattices through a diverse set of RVE-based finite element fatigue simulations. The model’s predictive capabilities are verified by comparing the simulation results with experimental fatigue data reported in the literature. The overall approach constitutes a unified setting for fatigue life prediction of additively manufactured microlattice structures ranging from low- to high-cycle regimes. It is also shown that the model can be applied to technologically relevant microlattices with mathematically-created complex microstructure topologies.