Sensitivity of void mediated failure to geometric design features of porous metals

TL;DR

This study examines how the geometric design features of porous metals influence void-mediated failure, using simulations and statistical models to understand failure probabilities related to internal porosity and geometry.

Contribution

It introduces a combined experimental and computational approach to analyze the impact of porosity and geometry on failure in additively manufactured metals.

Findings

Porosity distribution significantly affects failure locations.

Geometry influences the stress concentration and failure probability.

Statistical models can predict failure likelihood based on defect features.

Abstract

Material produced by current metal additive manufacturing processes is susceptible to variable performance due to imprecise control of internal porosity, surface roughness, and conformity to designed geometry. Using a double U-notched specimen, we investigate the interplay of nominal geometry and porosity in determining ductile failure characteristics during monotonic tensile loading. We simulate the effects of distributed porosity on plasticity and damage using a statistical model based on populations of pores visible in computed tomography scans and additional sub-threshold voids required to match experimental observations of deformation and failure. We interpret the simulation results from a physical viewpoint and provide statistical models of the probability of failure near stress concentrations. We provide guidance for designs where material defects could cause unexpected failures depending on the relative importance of these defects with respect to features of the nominal geometry.