Functionally-graded Lattice Topology Optimization of Conformal Fluid Channels

Abstract The recent advent of meal additive manufacturing made it possible to manufacture a solid structure with internal fluid channels with complex topology and geometry that closely conform the target surfaces for thermal management (eg., mold surface). This work presents a topology optimization (TO) of conformal fluid channels for thermal management of structures subject to the requirements for structural displacement and maximum stress. Examples of such structures are mold for injection molding, dies for diecasting, cooling jacket for batteries, and aerodynamic parts for jet and rocket engines. TO of lattice structures, known for superior stiffness-to-weight ratio and energy absorption capacity, have a potential for superior heat exchange between thermal fluid and structural solid owing to the increased surface area. The lattice structures are also beneficial for the printability of channels by significantly reducing the needs for support structures that are open difficult to remove after printing due to the narrow, internal channel geometry. Existing functionally-graded lattice TO methods based on bi-scale finite elements analysis, however, have a limited applicability since they often suffer from poor connectivity between neighboring lattice cells, which can be critical for fluid flow. To fill the gap, we present a lattice TO formulation for conformal fluid channels based on Solid Isotropic Material with Penalization (SIMP) and Darcy’s law for fully-coupled thermal-fluidic-structural analysis and a single-scale, neighborhood mask approach for functionally-graded lattice generation that ensures smooth meso-scale connections of lattices. Numerical examples demonstrate the formulation can successfully generate the functionally-graded conformal lattice channels that meet the requirements on temperature distribution as well as structural displacement and stress.