Biomimetic structure-based parametric optimization design using a multi-objective algorithm of the crash box for passenger vehicle

Abstract

Associated with the popularity and wider use of vehicles as common means of transport there is a fundamental concern of safety during a journey. The risk of injuries and fatalities is severe when the vehicle structure is crashed during a collision accident, especially in a front collision where the bumper system, in which crash boxes play a great role to absorb impact load. Over the current global traffic accidents occurred by vehicle accidents are a very crucial problem in public health. Especially, during front collision accidents of passenger vehicle number of occupants get injured and die because of the crash box not absorb all impact load energy come from beam bumper. An adequate design and sufficient strength of the crash box superstructure for passenger vehicles can reduce the number of injuries and fatalities. During the crushing of the vehicle, it involves a complex interaction between body structure and interior system. Therefore, the energy absorption system design of the vehicle crash box should be in such a way that it should absorb the energy created during impact and should have blocked the shock transfer to the occupant area. To improve the crashworthiness and energy absorption performance of the crash box, this study was proposed eight hexagonal honeycomb structures reinforced by ribs connection of spider web and core woodpecker based on biomimetic structure design techniques (methods). The honeycomb configuration has been widely applied in the energy absorption structure design due to its energy-absorbing potential and advantage, which has been validated by some numerical and experimental studies. Spider orb-web frame silk structure is stronger per unit weight, compared to high tensile steel and has very high toughness capability equal to 2.5×108 J/m3 or usually expressed by 1.5×105 J/kg. Also, the woodpecker is well known for the ability to absorb the strong shock from the process of drumming the hard trunk of trees and without any damage to its brain. After conceptual modeling, CAD modeling of these conceptual model structures is done in SOLIDWORK 2020 as a file of IGES. To evaluate the performances of models and compares each other the experimental simulation was carried out in LS-Prepost and post-process and LS-DYNA as a solver. As the ribs connection reinforcement increase with a constraint of mass to optimum point the crashworthiness of the crash box model was increased, as the P-5 (C2W) Multi-cell full quadrilateral and circular hexagonal tube and corner to wall ribs connection model result indicated. The result of P-5(C2W) was selected for validation and optimization, shows good agreement with three experimental results and improvement after parametric optimization in ANSYS 2020 R1 using a multi-objective genetic algorithm. After parametric optimization, the new optimized crash box of P-5(C2W) experimental simulation result shows good improvement of crashworthiness indicator than all other model and without optimization with the result of Peak Force 69.319 kN, mean crush force 25.99 kN, Total energy 9.060 kJ, Specific energy 6.864 KJ/Kg and crushing force efficiency (CFE) 0.375 respectively. The results of performance indicator for P-5(C2W) model after parameter optimization shows good increments specially in mean crush force which more countable for crashworthiness, with the result of 30.25 kN, peak crush force 69.13 kN, total energy 12.342 kJ and specific energy 9.35 kJ/Kg