Topology Optimization Design Of The Large Bus Frame

Bus body frame is the main framework bearing the weight of the bus.With the strength and stiffness being satisfied,it's senility on improving the bus's performance to lighten the body frame's weight.As the advanced report and hotspot in structural optimize field,topology optimization is the emphases and difficulty in this field.In this paper,the importance of light weighting vehicle structure and topology optimization is highlighted,an overview of domestic and overseas research is provided,the technological development trend and discuss the flaws of domestic research in this field is analyzed, and the design idea of using topology optimization to analyze and optimize the frame of large bus is put forward.Then,the theory of size optimization and shape optimization is introduced,the practical methods for application is analyzed including:thickness-Varying Method, homogenization method and variable density method,and various algorithms are provided consisting of Genetic Algorithm,Optimality criteria,Mathematics Programming and Lagrange multiplier method.Variable density method is finally selected as the method in this paper.The mathematic model of the bus body's frame for topology optimization is established based on variable density method,while the least flexibility to be the object and optimized cubage as the constraint.After that,the topology optimization model of the bus's frame is established,and optimization design is done with HyperWorks.There are many conclusions obtained via the analysis on topology optimization results.Founded on that and the frame's fabrication process,a new bus body frame is set up,through the results being manufactured disposed according to manufactured principle.The performance on new body frame is analyzed in order that the veracity of topology optimization design,dependability and practical significance are proved. The all-shell-element model of the large bus frame has been built according to the drawing provided by the client,stress and displacement of the whole bus frame under curve and torsion load cases have been computed,and finally strength and stiffness of the bus frame has been obtained.Finally,the modal analysis about the new bus body frame is processed.Seen from the result,the mass of the body frame is reduced by 37%.The greatest stress of curve and torsion load cases has been cut down separately.At the same time, the modes of the frame have been conformed to the request.The research results of this paper have not only provided reference and guidance for product design,reconstruct,optimization and solving practical problems in enterprise.The process how the lightweight optimization design on bus body frame is carried is given,and valuable economic benefit and social significance are provided.