Thin‐walled structures are used extensively in the passive safety of vehicles to absorb energy. The thin‐walled tube is already a traditional structure with excellent energy absorption. Negative Poisson's ratio (NPR) structures produce an inward concentration to increase the stiffness of the structure during axial compression. The concept of fluctuation of crushing force (FoCF) is introduced herein to evaluate this new energy‐absorbing box as an energy‐absorbing device based on the traditional energy absorption evaluation index. Based on experimental validation, a finite‐element model is developed that can accurately predict the crashworthiness of the double‐V NPR‐filled square tube (DVFST). The following parameters, such as out‐of‐plane thickness, meta‐cell half‐width beam thickness, and beam angle tube thickness, are conducted to assess the crashworthiness of the DVFST structure. The first thing that should be considered in the design of the DVFST structure is the half‐width of the cell, followed by the angle of the long beam, and then the relative wall thickness of the long and short beams. The DVFST structure has the potential to become an excellent energy‐absorbing device by adjusting its parameters.

<div class="section abstract"><div class="htmlview paragraph">The front end structure is an important role in protecting the vehicle and passengers from harm during the collision. Increasing its protective capacity can be achieved by increasing the thickness or replacing high-strength materials. Most of the current research is analyzed separately from these two aspects. This paper proposes a multi-objective optimization method based on weighting factor analysis, which combines material and thickness selection. Firstly, the optimized components are determined based on the 100% frontal collision simulation results. Secondly, six thicknesses and two materials of the front part of the vehicle body are selected as design variables to construct an orthogonal test design. In this paper, a weight-based multi-factor optimization method is used to numerically analyze the response results obtained by orthogonal experiments. Analyze the impact of each factor on the optimization goal to select the most reliable optimization. This optimization method can select the best material and component thickness combination scheme. The results show that the mass of the selected parts are reduced by 16.5%; the total energy absorption is increased by 5.2%; the intrusion in the dash is reduced by 8.9%; and the peak acceleration of the B-pillar is reduced by 39.2%.The material-structure integration optimization method is an effective method to solve the contradiction between lightweight and crashworthiness.</div></div>

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