Impact strength enhancement of aluminum tetrahedral lattice truss core structures

• Strength enhancement under impact of aluminum tetrahedral lattice materials.
• Experimental observation with the digital image analysis.
• Impact strength enhancement due to the lateral inertia effect.
• Numerical model reproduced observed events.

The present study aimed at understanding the behavior of tetrahedral lattice truss core structures under impact loading. Experimental investigations on tetrahedral lattice truss core structures made of aluminum 3003-O were performed using a standard testing machine and nylon split Hopkinson pressure bars. Results showed that the peak force increased about 23% from quasi-static loading to dynamic loading while the base material is hardly rate sensitive. In order to prove such a peak force increase was due to the lateral inertia effect, digital photography techniques were used to catch the deforming process of the core. A quantitive measurement of this process (length, shape) was extracted by a digital image analysis based on the edge detection algorithm. It was observed that the beams of the core were simply compressed at the early stage of loading before bending prevailing and this turning point took place much later under impact loading than the case of quasi-static loading. It was found that the beams were consequently more compressed before the occurrence of buckling during impact loading. This is the direct proof of the existence of the lateral inertia effect. Because of its important strain hardening capacity of base material (aluminum 3003-O), the observed peak force increase can be explained by this lateral inertia effect. Furthermore, numerical simulations using Abaqus code were also carried out to understand thoroughly the role of the lateral inertia effect played on the lattice truss core structures.