A Study On Layout Design And Multi-objective Lightweight Design And Optimization For A Pickup Truck Door

In the field of vehicle,the research of lightweight has become an important topic because of the rising problems about the polluting environment and the exhausting resources.This dissertation,not only establishes the finite model of torsion stiffness,drooping stiffness,lateral bending stiffness,modal frequency and dent resistance for vehicle door,but also analyses and evaluates each performance of vehicle door,by the layout and design of a pickup truck door structure.Due to the need for lightweight of vehicle door,the research of multi-objective optimization should be applied.And considering the uncertain interference factors,the robustness check and analysis should be done on the basis of multi-objective optimization,not only to reach the target of lightweight,but also to have the good robustness.The research is as follows:(1)In the layout stage,the layout of door hinge,glass lifter,check,lock,inner handle,outer handle and collision resistance beam should be completed by each main section graph of the vehicle door.In the design stage,each part of the vehicle door should be designed according to the layout of vehicle door,including the regularity of cross-arm glass lifter,the accelerated selection of glass lifter motor,the research of main door check arm shape and vehicle door seal.After the completion of layout and design,the kinetic simulation mechanism of vehicle door should be set up by the DMU module of CATIA,the practical movement state and constrained degree of freedom,to check the minimum kinetic gap between several significant parts and guarantee the rationality of layout and design.(2)The model of vehicle door is imported into HyperMesh to finish geometry cleanup and meshing.After the check and control of mesh quality,each part of finite model is connected by the methods of welding,bolting and gluing.Then the finite models of torsion stiffness,drooping stiffness,lateral bending stiffness,modal frequency and dent resistance are established by defining the material property of structural parts.On the basis of finite models,the simulation value of each performance is calculated by Optistruct.Each performance meets the design requests by the comparison of enterprise standard,but still have larger lightweight space.(3)Firstly,according to the parameter study and finite model analysis results of vehicledoor,8 design variables which have larger contribution are chosen to carry out sampling of design sample.Secondly,on the basis of sampling data and RSM theory,the RSM models of vehicle door mass,stiffness,dent resistance and modal frequency are built up,and then verifying the precision of RSM models.Finally,the RSM models of multi-objective optimization are set up by taking the chosen parts as design variables,taking vehicle door torsion stiffness,drooping stiffness,lateral bending stiffness and dent resistance as the constrains,taking the minimum mass and maximum first modal frequency of vehicle door as targets.Then,using the NSGA- â…¡ genetic algorithm,the non-Pareto optimal solution set of vehicle door mass and first modal frequency is achieved,and picking out the optimum solution which meets the optimization requests.The performances of vehicle door,after optimization,not only meet the enterprise standards,but also reach the targets,including the increment of first modal frequency and the lightweight of vehicle door.In this optimum solution,the vehicle door mass is 17.19 kg,reducing 0.97 kg,5.34% drop.However,the first modal frequency is 34.59 Hz,increasing 0.27 Hz.The quality level and reliability of vehicle door are analyzed by the descriptive sampling method of Monte Carlo simulation.The results,the Sigma quality level and reliability of each output response,are 8Sigma and 1respectively.Because the vehicle door,after multi-objective optimization,has the good robustness,it is not necessary to carry out robustness optimization.