Investigate the compression mechanism of 2D interlocking assembled cellular structures

The mechanical properties of traditional honeycomb materials cannot be adjusted after manufacturing, modular metamaterials have good flexibility and adjustability, this study aimed to develop an innovative 2D interlocking assembled cellular structure with self-locking capabilities, offering the flexibility to customize boundary shapes and mechanical properties by adjusting the assembly units. To achieve this, a series of structures with configurable units in both x and y directions were designed, and specimens were fabricated using polylactic acid (PLA) and carbon fiber-reinforced polymer (CFRP) materials. The research employed a combination of compression tests and finite element simulations to analyze the deformation patterns and failure modes of the specimens.​The main results revealed distinct differences in the structural behavior: three-column structures primarily developed unilateral shear bands, whereas five-column structures exhibited "V"-shaped or "X"-shaped dual shear bands. Furthermore, variations in compression velocity did not change the overall trend of the force-displacement curves; however, different compression velocities led to different deformation patterns. In terms of materials, structures made of PLA exhibited "N"-shaped deformation due to delamination-induced instability within the shear bands, while CFRP structures primarily underwent brittle fracture at the hinge points. The specific energy absorption (SEA) of CFRP is significantly higher than that of PLA. With the increase in the number of layers, the SEA slightly decreases. The increase in the number of columns has a relatively weak impact on SEA. The study offers practical guidance for the protective applications of self-locking cellular structures in various scientific and engineering fields, such as aerospace, automotive, and civil engineering.