Simulation Analysis Of Roof Crush Strength And Improvement Of Body Structure Based On The New Regulation

When the rollover accident occurs,the roof structure is affected by the impact load,which can cause serious deformation of the roof.The lower roof strength is the direct cause of the occupants' head and neck injury.So more and more people have paid attention to the crashworthiness of roof structure.In 2014,No.453 notice of MIIT claimed:it is necessary that the minibus load of roof crush should satisfy 3 times of the vehicle's curb weight,which the regulatory requirement's value doubles based on GB26134-2010.In this paper,the finite element method was used to deeply study the strength of roof crush of a minibus based on the new roof crush regulation.It is widely accepted that the poor simulation accuracy of the roof crush is failed to guide the new car exploitation and to deal with the problems in satisfying the modified regulation.This study focused on the simulation accuracy of roof crush in detail.Firstly,based on the principle of equivalence,the numerical model of windshield was established by setting failure strain to simulate the failure behavior of glass.It was realized to precisely simulate the deformation mode of the roof under crush.Then,the effect of loading velocity on the accuracy of the simulation has been studied,meanwhile,the suitable velocity value was calculated according to the minimum modal frequency.At last,the loading velocity was determined to be 1473.9 mm/s which resulted in an excellent progress in the efficiency of the simulation.Compared with the test result,the improved simulation model can more accurately reflect the situation of roof crush,and the simulation error is less than 5%.Based on the simulation model with high precision,the tolerance of roof crush was analyzed and the result showed that dissatisfied the new regulation's requirement.First of all,the structure of the main bearing components was improved by the way of load transfer path,focused on the analysis and discussion of the structural form of the B-pillar reinforcement and established the design discipline.The roof crush performance of improvement scheme satisfied the requirement of the new regulation,but the body weight has increased by 7.85 kg.With consideration of applying high strength steel and thinning thickness of the main components,the modified scheme satisfied the requirements of the latest regulation with a minor weight increase of 3.16 kg.Finally,the optimization scheme was used to verify the performance of vehicle body and the test of the strength of roof crush.The verification results satisfied the performance requirements.The results show that the method of simulation analysis and optimization design can provide guidance for the development design of the same type of vehicle,and it has good practical application of the engineering.