Research On Multi-body Cooperative Optimization Method Based On Conceptual Design

Automobile light-weighting is an important research topic in the 21 st century,which can not only alleviate energy shortage,but also reduce environmental pollution.The body light-weighting is one of the important ways to realize the lightweight of the car.Usually,the car body design has three stages: conceptual design,detailed design and testing.In the conceptual design stage,defects caused by poor body structure design are difficult to correct in the subsequent detailed design process.In addition,the modular platform design of the body can greatly shorten the vehicle development time and reduce manufacturing costs.Therefore,this paper conducts research on multi-body collaborative optimization methods in the conceptual design stage,to lay the foundation for modular platform design that meets the requirements of automotive lightweight.Based on the SIPESC solver,this paper studies the single-body structure optimization method,and thus carries out the research on the multi-body collaborative optimization method,which is integrated in the self-developed software platform(S-i VCD).The specific research content of this article is as follows:(1)Research and implement the single-body optimization method.Taking the frame car body as research object,the paper calculates the key static performance of the car body through SIPESC,provides the calculation method of the response function and its gradient according to the flow of the single-body optimization method,and determines the parameters for calculating the gradient of the response function.The single-body optimization method takes the body mass as the optimization goal,the bending stiffness and torsion stiffness of the body as the optimization constraint function,and the cross-section size of the body as the optimization variable to establish a mathematical model,and use the moving asymptotic method to perform iterative calculation.Numerical examples show that the single-body optimization method can reduce the mass of the frame body while meeting the requirements of the bending stiffness and torsion stiffness of the frame body,and has a better lightweight effect.(2)On the basis of single-body structure optimization,combined with the idea of multi-disciplinary collaborative optimization,the paper proposes a multi-body collaborative optimization method.Combining the process of the multi-body collaborative optimization method,the calculation method of the response function and its gradient is given.Through a numerical example,the multi-body collaborative optimization is compared with the individual optimization of each frame body and the multi-body layered optimization to verify the reliability of the algorithm.The multi-body collaborative optimization method reduces body mass while meeting the requirements of frame body bending stiffness and torsional stiffness,and also ensures that the shared variables of different frame bodies are equal,which lays the foundation for the modular platform design to meet the requirements of automobile lightweight.(3)The paper independently developed a data-driven vehicle body structure conceptual design and optimization system(S-i VCD),which mainly realized the body structure analysis module and the body structure optimization module.S-i VCD applies the single-body optimization method and the multi-body collaborative optimization method to realize the functions of body structure analysis and optimization design,and simplify the body structure design work.To sum up,this article researches and realizes the single-body optimization method in the conceptual design phase of building body structure,proposed a multi-body collaborative optimization method based on the single-body structure optimization work,and finally independently developed a data-driven vehicle body structure conceptual design and optimization system(S-i VCD),which applied the vehicle body optimization method studied in this paper.