Multi-Material Topology Optimization Considering Dissimilar Material Joining Cost And Natural Frequency

Abstract

The recent drive for producing lightweight and high-performance designs on reduced timelines in both automotive and aerospace industries has promoted the development of computational design, analysis, and optimization tools. Topology optimization (TO) has been recognized as a foremost method to reduce weight in both component and assembly level design. Optimum loadpaths within a designable region are determined, providing non-intuitive designs that can result in significant weight savings while adhering to structural performance criteria. Multi-material topology optimization (MMTO) is a subset of TO, which is recently gaining greater focus due to its lightweighting capabilities and increased industry focus on the adoption of composites in design. MMTO extends the TO problem to consider material selection and material existence simultaneously. Multi-material solutions, therefore, represent an assembly where each section of dissimilar material is a different component. Conventional MMTO; however, presents two complications first being that it does not consider dissimilar material joining during the optimization process and second that it provides design ideas requiring significant manual interpretation to be manufactured using conventional methods. This manuscript address both of these challenges and further extends the MMTO methodology to consider fundamental frequency in the design process. The first topic of Material Interface Control in Multi-Material Topology Optimization using Pseudo-Cost Domain Method presents a novel pseudo-cost domain (PCD) method to mathematically determine individual material interfaces in MMTO solutions. The proposed methodology employs a user-defined joint cost model to weigh the distinct material interfaces relative to each other. An innovative approach to tailor the MMTO design considering the relative cost of each material interface is presented. The proposed methodology can consider any number of materials and their respective interfaces. This proposed PCD method is used to design an electric all-terrain vehicle. During the designing process, it was found that using the PCD method 80% reduction in the total joining cost of the design was obtained while sacrificing just 4.2% of the design’s stiffness when compared to conventional MMTO design. The manuscript also extends the MMTO methodology to incorporate frequency, symmetry, extrusion, and draw direction constraints in large scale practical models providing designers with more manufacturable and institute design from onset thus, requiring less manual reinterpretation.