An investigation of the crashworthiness performance and optimization of tetra-chiral and reentrant crash boxes

In this study, the crash performances of square and cylindrical crash boxes with tetra-chiral and reentrant unit cell structures were explored and optimized. First, tensile tests were conducted to determine the mechanical properties of the Al 6061-T6. These mechanical properties were then incorporated in the finite element (FE) models generated using LS-DYNA. To validate the FE models, tetra-chiral and reentrant crash plates were produced, and the FE analysis results were compared with the test results. Subsequent to this validation, for each crash box design type (i.e., tetra-chiral cylindrical, tetra-chiral square, reentrant cylindrical, and reentrant square), Kriging surrogate models were constructed using MATLAB for two crash metrics: specific energy absorption (SEA) and crash load efficiency (CLE). Finally, a multi-objective optimization problem was formulated for each crash box design type, the generated Kriging models are integrated into genetic algorithm available in MATLAB, and the Pareto optimal crash box designs were obtained. It was found that the SEA and CLE of reentrant crash boxes were better than those of the tetra-chiral crash boxes. In addition, the reentrant cylindrical crash box displayed better performance than the reentrant square, as well as the tetra-chiral cylindrical and square crash boxes.