Efficient Design Optimization of Variable-Density Cellular Structures for Additive Manufacturing: Theory and Experimental Validation

Author: Lin Cheng, Pu Zhang, Emre Biyikli, Jiaxi Bai, Joshua Robbins, Matthew E. Lynch, Evan J. Butcher, Albert C. To
Rapid Prototyping Journal, 23(4), pp. 660-677, 2017
DOI: 10.1108/RPJ-04-2016-0069 

Abstract:

Purpose
The purpose of the paper is to propose a homogenization-based topology optimization method to optimize the design of variable-density cellular structure, in order to achieve lightweight design and overcome some of the manufacturability issues in additive manufacturing.

Design/methodology/approach
First, homogenization is performed to capture the effective mechanical properties of cellular structures through the scaling law as a function their relative density. Second, the scaling law is used directly in the topology optimization algorithm to compute the optimal density distribution for the part being optimized. Third, a new technique is presented to reconstruct the computer-aided design (CAD) model of the optimal variable-density cellular structure. The proposed method is validated by comparing the results obtained through homogenized model, full-scale simulation and experimentally testing the optimized parts after being additive manufactured.

Findings
The test examples demonstrate that the homogenization-based method is efficient, accurate and is able to produce manufacturable designs.

Originality/value
The optimized designs in our examples also show significant increase in stiffness and strength when compared to the original designs with identical overall weight.