Multi-objective topology optimization of passive heat sinks including self-weight based on triply periodic minimal surface lattices

Advancements in additive manufacturing technology allows design of novel lightweight passive heat sink based on triply periodic minimum surfaces (TPMS) lattices. Topology optimization has been adopted to obtain efficient lightweight passive heat sink designs that maximize heat dissi-pation. However, in the topology optimization framework, the mechanical loads are usually not considered which limits its application under severe loading conditions. This paper presents a multi-objective topology optimization based on Solid Isotropic Method of Penalization (SIMP) approach that simultaneously optimize both thermal and structural objective functions to yield optimized structures with better heat dissipation and enhanced structural integrity. Three load cases are studied considering both the thermal and structural load scenarios. For each scenario, a weighted sum method is used to linearly combine the two objective functions in order to obtain the Pareto front. The obtained optimal configuration is further transformed to generate a TPMS-based structure employing a novel density mapping approach. Primitive (P), Diamond (D), Gyroid (G), and IWP TPMS structures are considered. To further study the effectiveness of mapping, the thermal performance of the mapped structures is measured using the effective thermal conduc-tivity The mapped Primitive TPMS-based structures were found to possess superior heat con-duction performance compared to other mapped TPMS structures. The unit cell mapping sensitivity along and perpendicular to heating direction was also investigated. It was found out that increasing number of unit cells in a direction perpendicular to heating direction enhanced the structure's effective conductivity. The structural integrity of the mapped heat sink structures were also examined measuring their strain energy density under both self weight loads and external structural loads.