Buckling and yield strength estimation of architected materials under arbitrary loads

TL;DR

This paper introduces a simple, accurate method to estimate the buckling and yield strength of architected lattice materials under arbitrary load conditions, improving design efficiency for complex stress scenarios.

Contribution

A novel simplified analysis method for buckling and yield strength of stretch-dominated lattice structures under general loads, verified by numerical analysis.

Findings

Complete buckling strength surfaces computed for various lattice structures.

Buckling strength ratios vary with load orientation, up to 2.41.

Created a more isotropic buckling strength configuration without losing stiffness.

Abstract

Buckling strength estimation of architected materials has mainly been restricted to load cases oriented along symmetry axes. However, realistic load scenarios normally exhibit more general stress distributions. In this paper we propose a simple yet accurate method to estimate the buckling strength of stretch-dominated lattice structures based on individual member analysis. As an integral part of the method, the yield strength is also determined. This simplified model is verified by rigorous numerical analysis. In particular, we efficiently compute the complete buckling strength surfaces of an orthotropic bulk modulus optimal plate lattice structure and isotropic stiffness optimal plate and truss lattice structures subjected to rotated uni-axial loads, where the ratio between the highest and lowest buckling strength is found to be 1.77, 2.11 and 2.41, respectively. For comparison, we also provide their yield strength surfaces, where the corresponding ratios are 1.84, 1.16 and 1.79. Furthermore, we use the knowledge gained from the simplified model to create a new configuration of the isotropic plate lattice structure with a more isotropic buckling strength surface and buckling strength ratio of 1.24, without deterioration of the stiffness or yield strength. The proposed method provides a valuable tool to quickly estimate the microstructural buckling strength of stretch-dominated lattice structures, especially for applications where the stress state is non-uniform such as infill in additive manufacturing.