Impact performance of plate-like topological interlocking structures: Interlocking metrics for diverse designs

Topological interlocking (TI) structures emerge as a promising design strategy for advanced engineering applications, offering enhanced energy dissipation and localised failure modes. This study investigates the impact performance of plate-like TI structures composed of elements with curved interfaces, focusing on the effects of two distinct geometric design factors: base polygon shape and interface morphology. Four interlocking metrics, including contact area, contact area ratio, Gaussian curvature, and critical inclination angle factor, are proposed to quantitatively assess the mechanical performance of these structures. Finite element simulations are employed to evaluate their behaviour under various drop heights, analysing energy dissipation, stress distribution, and deformation characteristics. Simulation results reveal that the base polygon shape significantly influences contact area and load transfer efficiency, while interface morphology affects stress dispersion and deformation behaviour. Strong correlations are found between the proposed geometric metrics, including contact area, contact area ratio, and critical inclination angle factor, and key mechanical responses like energy dissipation and maximum displacement. In particular, larger critical inclination angle factors promote broader stress propagation and improve energy absorption. Additionally, regions with high Gaussian curvature align with stress concentrations and failure initiation, providing a basis for predicting failure zones and guiding reinforcement design. These findings provide a quantitative foundation for optimising TI structures under impact loading.