Energy absorption performances of lattice structures with unevenness strut diameter under uniaxial compression

Strut-based lattice structures characterized by high-energy absorption control and low weight are considered excellent lightweight candidate materials in many fields such as aerospace, automobile manufacturing, and rail transit. However, for cells with a lattice structure, the design parameter dimensions of the strut diameters are essentially the same. This even distribution of internal strut diameters makes it difficult to efficiently improve the energy absorption and weight reduction effects of the lattice structure. To address these problems, the face-centered cubic (FCC) lattice structure is selected as the research object. Through the design of uneven strut diameter distributions, evenness is introduced to maximize the simultaneous improvement of energy absorption and weight reduction. The FCC lattice structure are fabricated using digital light-processing photocuring technology, and quasi-static uniaxial compression experiments are conducted using an electronic universal testing machine. Subsequently, a finite element analysis model of the lattice structure is established using LS-DYNA. The deformation and force–displacement results of the experiments and simulations are found to be consistent. Four types of FCC lattice structures with varying homogeneities were designed: horizontal strengthening, horizontal cross strengthening, vertical strengthening (VSFCC), and vertical cross strengthening (VCSFCC). Based on a finite element analysis model, the effects of lattice different relative densities and evenness on the energy absorption performance of the structures is analyzed. The results confirm that the VSFCC scheme is the optimal lattice structure for uneven strut diameters, characterized by a deformation process of progressive crushing and overall bending. The VSFCC lattice structure significantly improves energy absorption performance. Compared to the original FCC lattice structure, the specific energy absorption of the VSFCC lattice structure increases by up to 108.02%, and the increase in PCF value is stable at ~110%. At the same PCF value, the specific energy of the VCFCC lattice structure increases by 38.79%, while the relative density decreases by 32.97%. The VSFCC lattice structure has a tailor-made energy absorption performance and potential to be an excellent light energy absorber. The research results provide a certain reference value for the energy absorption design of lattice structures.