Boundary conformal design of laser sintered sandwich cores and simulation of graded lattice cells using a forward homogenization approach

Abstract

Laser sintering enables the production of large and complex thin-walled structures. Based on a stiffness evaluation and the manufacturability, a design approach for the additive manufacturing of large, complex, multi-curved sandwich structures was investigated through the creation of lattice structures. Therefore, unit cell and sandwich beams with lattice cell cores were modeled, simulated, manufactured, and tested. The change in lattice cell shape from a periodical structure into a non-periodical structure was shown on a demonstrator. A simulation of the sandwich beams was conducted using full solid and forward homogenization models with simple and complex elastoplastic fitted unit cells (UCs). The test specimens were printed, and three-point bending (3PB) tests were conducted. The simulation results show good agreement with the experimental data for truss-based lattice structures for periodic (7% deviation) and non-periodic lattice cell cores. To verify the design approach, a demonstrator of a segment of a racing motorcycle front fairing was designed and manufactured. Keywords: Non-periodic lattice cells, Multiscale simulation, Sandwich, Additive manufacturing, Motorcycle design