Structural Design and Dynamic Compressive Properties of Ti–6Al–4V Hollow Lattice Structures

Herein, three groups of Ti–6Al–4V hollow lattice structures with different strengthening structures are designed and manufactured using a selective laser melting method. A basic structure (specimen BS), a basic structure with strengthening structures at joints (specimen SJ), and a basic structure with a strengthening structure on tube walls (specimen SW) are compressed by a split Hopkinson pressure bar system. The potential influence of strengthening structures and strain rates on dynamic compressive properties is investigated. The results indicate that the strengthening structures change the structural weaknesses and stress concentration regions inside the basic structures; thus, specimens BS and SJ collapse on the struts, whereas specimen SW breaks at the joints. The strengthening structures of specimen SJ reinforce the nonstructural weaknesses inside the basic structure, resulting in the mechanical properties showing limited improvement or even decrease. However, the strengthening structures of specimen SW strengthen the structural weaknesses inside the basic structure, so the collapse strength, specific collapse strength, energy absorption (EA), and specific EA (SEA) of specimen SW, respectively, increase by 46.1%, 8.4%, 42.0%, and 6.5%, which shows that specimen SW exhibits excellent mechanical properties. Moreover, strain rate sensitivity of specimen SW is dominated by the strain rate effect of Ti–6Al–4V material.