Fast Calculation For The Stiffness Chain Model Of Car-body Based On Parameters Of Main Section

The car-body engineering design stage of car forward development process can be divided into conceptual design and detailed design.Conceptual design is the early stage of car-body structure design,the task is to provide a structural feasible scheme for the detailed design.The overall structure and performance of car-body depends on the result of conceptual design,once left defects in design,it is difficult to make up in the subsequent process.The modern car-body generally adopts load-supporting structure,car-body need to fend against complex load when moving,so it add particularly importance to the stiffness performance.Car-body main section is distributed in the body of each important position,to describe the details of the cross section.It is not only the key point of car-body that controlling structure and performance,but also an important instrument to describe car-body structure scheme in the conceptual design.The shape and dimension of car-body main section is an main factor affecting the performance of car-body stiffness.Therefore,the main section design is an important part of car-body structure conceptual design.The research is around the issue of parameterized method of main section and car-body stiffness distribution in conceptual design phase.The high efficiency of computing model of stiffness chain by using the parameters of real main section directly is the key problem which must be solved in the design of vehicle body stiffness chain.With the controllable and engineering parameters of stiffness chain nodes as target,this paper builds the correspondence between the parameters of stiffness chain nodes and the section attribute parameters of cross section of main section,studies the parameterized method of controlling the real shape of main section through the polar coordinate method and computing method of complex section properties adopting single variable control theory based on an established and improved computing model of vehicle body bending static stiffness chain.It achieves the targets that properties parameterized calculation of stiffness chain nodes and engineering of parameters in stiffness chain model,which lays a foundation for the researches of static stiffness optimal distribution based on real main section structure and shape.Stiffness optimum distribution was studied based on car-body stiffness chain and the mathematic model of car-body bending stiffness optimum distribution was built and then solved by genetic algorithm to obtain the equivalent stiffness of main sections.The rationality of stiffness optimum distribution and the availability of car-body stiffness chain were verified by comparing with the CAE analysis of approximate benchmarking car.Finally,this paper has studied fast parametric modeling of car-body driven by parameters of main section and achieved the transformation of stiffness chain model and three-dimensional model of car-body based on technology of skeleton model.This study provides valuable reference for the domestic automotive enterprises to carry out the top-down conceptual design,and discuss a new idea to improve the independent research and development level of domestic auto industry.