Crashworthiness Optimization Design Of Vehicle Body Parts With Negative Poisson's Ratio Structure

The crashworthiness of vehicle body parts is an important content in the field of passive safety.The crash box is a key energy absorbing part in front collision,and the B-pillar is closely related to the survival of passengers in side collision.Aiming at the disadvantages of unstable deformation and poor energy absorption effect of traditional crash box and B-pillar in collision process,this paper proposes a novel crash box and B-pillar based on negative Poisson's ratio(NPR)structure with the advantages of light weight,good energy absorption effect and strong impact resistance to improve the crashworthiness of vehicle in front and side collision.The main research contents of this paper are as follows:Firstly,a novel crash box and B-pillar based on NPR structure are proposed.A microscopic NPR unicellular structure with concave hexagonal shape is adopted,and the macroscopic NPR inner core structure of crash box and B-pillar is designed by the spatial rotation and array of the unicellular structure.Then,the reliability of the front collision and side collision model are verified based on RCAR regulation and ECE R95 regulation,respectively.Secondly,the crashworthiness of two-dimensional and three-dimensional NPR crash boxes are analyzed in front collision,and it reveal that the three-dimensional NPR crash box has better crashworthiness.The optimal Latin hypercube experimental design method is used to select sample points within the range of design variables,and an approximate model of each crashworthiness evaluation index of NPR crash box is established based on response surface model method.The parameters of microscopic NPR unicellular structure are optimized by multi-objective particle swarm optimization.Finally,the crashworthiness of different B-pillars is analyzed in side collision.The design variables which have significant impact on the crashworthiness of B-pillar are screened out by factorial design method.An approximate model between the design variables of NPR B-pillar and the crashworthiness evaluation index is established based on the experimental design and polynomial response surface methodology.The non-dominated sorting genetic algorithm and standard boundary intersection method are used to optimize the design and determine the optimal solution.In this paper,the NPR structure is introduced into the crashworthiness design of body parts.The research results can provide a certain theoretical basis and technical support for the design and development of body parts.