Dual-purpose architected materials: Optimizing graded BCC lattices for crashworthiness and heat dissipation

Abstract: Body-centered Cubic (BCC) lattice structures demonstrate promising performance for applications that require simultaneous mechanical energy absorption and thermal management. However, current optimization approaches are typically confined to single-domain objectives, such as mechanical parameters like impact energy and peak stress, neglecting the role of multiple physics in real-world performance. To address this, we propose a multi-objective optimization framework for density-graded BCC lattices that effectively dissipates heat while maximizing absorbed impact energy. A parametric three-zone lattice configuration is investigated to explore various trade-offs between mechanical and thermal properties. Each design is evaluated through independent impact and forced-convection simulations using commercial solvers. Specific Energy Absorption (SEA) and peak stresses at the distal end quantify impact absorption performance, while the Nusselt number and pressure drop characterize thermal dissipation performance. Surrogate models constructed from this data enable multi-objective optimization via Goal Programming to identify an optimal design. Two Pareto-optimal lattice designs are identified with reduced pressure drop and peak stress, underlining the superiority of strategic density gradation. Analysis of the optimal designs reveals how material distribution and geometric design variables influence mechanical-thermal trade-offs, establishing quantitative design guidelines for lattice structures in this multi-physics application.