Experimental investigations of the effectiveness of simultaneous topology/orientation optimization via SOMP and principal stress directions

Abstract

This article presents an analysis of simultaneous topology and orientation optimization based on a principal stress method within the Solid Orthotropic Material with Penalization (SOMP) framework. Numerical case studies were done to assess the expected benefits of including orientation in the design process for minimum compliance structures under single load cases printed with orthotropic materials. In particular, comparisons were made between structures designed with and without consideration of orthotropic material orientations during the topology optimization (TO) process. Direct-Ink Writing (DIW) additive manufacturing (AM) was used to print experimental specimens, which were tested in bending to validate numerical results. The novelty of the work centers on the experimental evaluation of the performance of optimized topologies designed with SOMP and manufactured via DIW. Additionally, new knowledge is presented in the form of corresponding numerical and physical experiments showing that with a principal-stress based material orientation updating scheme, equivalent performance can be achieved with respect to compliance by 1) optimizing topology and orientation concurrently with orthotropic material orientations controlled during TO using maximum in-plane principal stress directions; or 2) optimizing topology assuming equivalent isotropic properties, and substituting the original orthotropic properties along principal stress orientations post-optimization. This experimentally validated finding confirms that including orientation in the compliance-based design framework for AM of structures with orthotropic materials is not advantageous. For single load cases, using the standard Solid Isotropic Material with Penalization (SIMP) method for design purposes and then aligning material orientations with principal stress orientations after the design is produced is sufficient for obtaining equivalent performance benefits.

Keywords

• Additive manufacturing
• Direct-ink write
• Orientation optimization
• Material anisotropy
• Topology optimization
• Composites