Lightweight Design And Research On Frontal Impact Performance For Bus Body Frame

The current energy shortage and environmental degradation have become the focus of attention.Light weighting the car effectively can improve the performance of the vehicle and achieve the goal of energy conservation and emission reduction at the same time.As the main force component of passenger car,the body skeleton needs to have sufficient structural safety performance to meet the specific use requirements.In this paper,the body structure of the 12-meter-bearing aluminum alloy bus is used as the research object,and the structure of the bus body structure is designed in a lightweight way by method of dimensional optimization.The main research content and conclusions are as follows:1.According to the three-dimensional geometry model of the passenger car body,the static analysis finite element model is established in the finite element software HyperMesh,and the four conditions of horizontal bending,limit twisting,sharp turning and emergency braking are set.In the OptiStruct solver software,the strength of the body is simulated and verified to satisfy the strength requirements in 4 common driving conditions.2.Based on the basic method of structural static sensitivity analysis,the optimal design function of OptiStruct software is applied,the strength performance of the body structure is considered comprehensively,and the sensitivity analysis of all parts of the body is carried out under 4 operating conditions,so that the sensitivity of each part of the body is sorted about static stress and mass under different operating conditions.Using the method of direct sensitivity and relative sensitivity,the thickness of 18 parts suitable for the lightweight design of the body was filtered out,and finally combined with the impact of the safety performance of the vehicle's frontal collision,the absorbent components of the front of the body were removed,and 15 design variables were finally involved in the lightweight.3.With the thickness of 15 parts as the optimization design variable,the stress value of the body structure in 4 conditions is less than the required stress value of the material as a constraint,the overall mass of the body skeleton structure is the minimum target function,the body optimization method is used to establish the body optimization analysis model in OptiStruct software.The lightweight design of the body structure results in a reduction of 8.3% in the light weighting of the passenger car.Comparing the static strength performance of the lightweight passenger car body structure with the body before the lightweight,it is verified that the lightweight body still meets the strength requirements.4.The limited element model of passenger car body collision analysis before and after lightweight is established,and the front 100% rigid barrier collision analysis is carried out on the body structure using LS-DYNA software.Comparing the energy change curve in the analysis results of the two collisions,the acceleration time course curve of the vehicle's central position,and the amount of intrusion in the front circumference of the vehicle,it is proved that the lightly quantified passenger car structure has less centroid acceleration,the driver's living space is larger and has better collision performance.