Modelling the impact-damage behaviour of composite sandwich panels with functionally-graded TPMS-latticed cores

Abstract

Advances in 3D printing technology have driven the digital design of multifunctional lattice structures for use in sandwich panel applications. However, understanding the intrinsic relationship between lattice-core topological features, especially when functionally graded, and impact properties is crucial for designing lightweight sandwich panels. Therefore, this paper simulates the low-energy drop-weight impact behavior of 3D printable sandwich panels composed of a stainless steel 316L sheet-based minimal surface lattice core and Prepreg skin. The study examines how cell size, relative density, topology of the lattice, and control of anisotropy in the core through periodicity gradation influence the low-energy impact-damage behavior of sandwich panels. The results indicate that the impact-damage behavior of sheet-based minimal surface-lattice sandwich panels is highly dependent on the core’s topological features. Notably, controlling anisotropy within the lattice core significantly enhanced the impact properties of the lightweight sandwich panel. Varying the periodicity of the Schwartz Diamond topology to control anisotropy in the lattice core improved the peak load and internal energy-to-maximum penetration ratio of the sandwich panel by 35.2 % and 42.4 %, respectively, for the same average relative density of 20 %. Moreover, combining periodicity gradation and relative density gradation using the same topology minimized damages to the frontal panel, in addition to contributing to 117.4 % and 130.6 % increase in peak load and specific energy absorption of sandwich panels, respectively, alongside a considerable rise in energy dissipation capacity. Furthermore, combining multiple lattice-topology functional gradation techniques proved essential in limiting failure localization and thus, improving the impact-damage tolerance of the sandwich panel. The study highlights the importance of combining various lattice-topology functional grading strategies to control the anisotropy and deformation behaviour of minimal surface lattices under drop-weight impact loads. These findings are crucial for designing high-impact protective and lightweight sandwich panels for diverse engineering applications.