Crashworthiness analysis of the biomimetic lotus root lattice structure

Lattice structures and biomimetic structures are lightweight and have high specific energy absorption and mechanical properties. They have been developed and widely used as energy-absorbing structures. Bionics and lattice structures are integrated in this study to design a biomimetic lotus root lattice structure (BLRLS) with hourglass-shaped cells. The BLRLS unit cells are stacked in the x, y, and z directions utilizing the technology of additive manufacturing. The mechanical characteristics of the BLRLS under uniaxial compression were studied, and the corresponding finite element model was verified by quasi-static experimental results. The deformation and the energy absorption mechanisms of the BLRLS were also analyzed using the verified finite element (FE) model. An empirical formula for the mean crashing force of BLRLS was subsequently derived. The results show that: the crash performance indicators initial peak crushing force (IPCF), energy absorption (EA) and the average of the crushing force (MCF) of the experimental and numerical were found to be 2.68 %, 0.52 % and 3.54 %, respectively. As height coefficient (CH) and wall thickness (t) increase, the crashworthiness (mean force, energy absorption and specific energy absorption) of BLRLS will be improved. The radius coefficient (CR) of the BLRLS has a significant effect on its deformation mode. When CR is less than 0.6, the BLRLS exhibits a petal shaped deformation mode; when CR is greater than 1 (R > r), the cell body of the energy absorbing structure is inward concave, which R and r represent the cell major radius and cell minor radius, respectively. The errors between the theoretical predicted values and the experimental and finite element models are 7.8 % and 11.1 %, respectively. Additionally, the BLRLS exhibits desired deformation mode during compression, resulting in high EA and specific energy absorption (SEA), and great potential in engineering applications.