The Reliability-based Optimization Design For Vehical Structures Coupled Process-performance

In the 21st century,the lightweight and crashworthiness design have been two main challenges in the vehicle industry,which often conflict with each other.To achieve lightweight while improving the crashworthiness,design optimization techniques have been widely used.However,traditional crashworthiness optimization and process optimization are always performed respectively.That is,few process requirements are considered in the crashworthiness design which may lead to non-optimal or even impractical process characteristics,and vice versa.Meanwhile,most of the energy absorbing members in vehicle body are fabricated by stamping process which will cause non-uniform thickness,residual strains and stresses,especially for those steel with high ductility and strength.Furthermore,the stochastic uncertainties associated with the material properties,process and geometry are propagated and represented to process and crashworthiness responses.In other words,a deterministic optimization could lead to unreliable or unstable designs.To address these issues,a multi-objective reliability-based design optimization coupled process-performance(MORBDOCP)was proposed.This method developed a finite element-based sequential coupled process-performance(FEBSCP)approach,which can improve the accuracy of the simulation.Then a reliability-optimum design method was applied to optimize the process and the performance of the parts while the reliability of the design was improved.In order to validate this method,the double-hat thin-walled structure(DHTS)was taken as the research object in this paper.The influence of the forming effects on the crushing behavior were investigated by using the FEBSCP approach.And then the optimization problem was defined in which the forming ability was considered as the constraint and the crashworthiness was taken as object.Finally,the reliability optimization algorithm combined with the surrogate model technologies and the global sensitivity analysis(GSA)was adopted to optimize the DHTS.As a result,the forming ability and the crashworthiness were improved significantly and the reliability of the design was improved compared with the deterministic optimization.In addition,the MORBDOCP was combined with the Tailor Roller Blank(TRB)technology and the DHTS which was made of TRB was optimization designed.The material property of the TRB was studied by the the uniaxial tensile test.The interpolation method was adopted to build the stress and strain field of the TRB according the test date which solved the problem of the material model.Then the modeling approach of the TRB structure’s forming and crashing simulation are studied.Finally,the MORBDOCP method was adopted to design the DHTS which is made of TRB.As a result,the formability and crashworthiness are improved.At the same time,the reliability of the optimal results are enhanced.This method had a certain reference value in the design of the TRB parts.