Optimization Study Of Body Structure Considering Crashworthiness

Domestic vehicle ownership is increasing year by year and the amount of traffic accidents increased,but the accident casualty rate showed a steady decline in the trend,in addition to the driver’s safety awareness to improve and the excellent body structure also plays an important role.Excellent body structure can ensure the safety of passengers in dangerous and effectively reduce the casualty rate in accidents.Therefore,it is of great practical significance to develop a body structure with good crashworthiness.The front and rear of vehicles on high-speed roads have the highest probability of collision,while frontal offset collisions and side collisions are common more on low and medium-speed roads such as cities.So,the article uses the 2018 version of china’s new car assessment program(2018C-NCAP)as a benchmark to create a whole-vehicle model of a passenger car movable deformable barrier for side impact(MDB)and frontal 40%offset deformable barrier(ODB)and solves it with the solution software LS-DYNA,using the post-processing software Hyperview to extract the deformation time sequence diagram of important components and the extracted results are compared with the target values to evaluate the crashworthiness of the vehicle.Based on the deformation time series diagram and the measured point values,the causes of poor crashworthiness are accurately analyzed,and the MDB and ODB working conditions are optimized using the proxy model method and the empirical method respectively.For the MDB condition,the design variables are firstly selected and parameterized according to the design experience,and the sample model is generated by the design Latin hypercube test and solved by the software LS-DYNA,and then the kriging,radial basis function and polynomial response surface proxy models are simultaneously generated and optimized with sensitivity by combining the variables and calculation results,and finally a hybrid algorithm based on genetic algorithm and gradient algorithm is used to optimize the crashworthiness with the body mass Finally,a hybrid algorithm based on genetic algorithm and gradient algorithm is used to optimize the body mass with the minimum as the objective and the displacement and velocity target values of B-pillar,front and rear doors and threshold measurement points as the constraints.For the ODB condition,the optimization was carried out from the perspective of improving the energy absorption of the components and enhancing the strength of the occupant compartment.The components were finally optimized based on the component sensitivity and design experience and with the material and thickness as variables,and the reinforcement plates were also added to the main force transfer paths when replacing the component material and thickness.The study results show that the optimization of body structure by proxy model method and empirical method to improve the crashworthiness of the whole vehicle is effective.After optimization,the energy absorption of main energy-absorbing parts in ODB condition is improved,and the deformation state and deformation time are controlled,while the deformation of important parts of occupant compartment such as B-pillar and front and rear doors in MDB is also controlled,and the intrusion rate of measurement points is also reduced,so that occupant safety is better guaranteed.In addition,the optimization process found that the two types of optimization methods present the following characteristics:(1)optimization effect,both types of methods can achieve the purpose but the agent model method can also achieve multi-objective optimization.(2)In terms of optimization efficiency,the optimization efficiency of the agent model method is higher than that of the empirical method.(3)In terms of modeling time,the agent model method takes a long time to model and requires high computational resources,while the empirical method is simple to model and has a short optimization period.(4)In terms of engineering applications,the agent model method is contradictory in terms of optimization effectiveness and optimization efficiency,and the degree of engineering applications is less than that of the empirical method,but the application trend of future optimization research.This paper uses the agent model method and the empirical method to optimize the crashworthiness of vehicles while comparing the characteristics of the two types of optimization methods in engineering practice,and provides a reference for the selection of body structure optimization methods.