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.

Figures (23)

• Figure 1: A BCC lattice-based heat sink consisting of (a) uniform struts is replaced with (b) a lattice consisting of diameter-graded struts. A cross-section of the hypothesized FG-BCC lattice with a density gradient is also .
• Figure 2: The uniform ground lattice (a) is geometrically compared to a discretized FG-BCC lattice (b), consisting of three planar zones. This discretization yields four distinct diameter values: $d_0$, $d_1$, $d_2$, and $d_3$. These four diameters dictate the geometry of any FG-BCC lattice in this work and will serve as the design variables
• Figure 3: Schematic showing the geometric features of an FG-BCC unit cell. The steps shown in the figure outline the simplified process for estimating area porosity, an indirect, approximate measure of relative density
• Figure 5: The final set of 16 evenly spaced ($d_1$, $d_2$) points (shown in green) in our feasible region represents our training geometries
• Figure 6: The forced convection simulation setup in Ansys Fluent comprising the FG-BCC-16 lattice