Research On Lightweight Of A Passenger Car Frame Under Multiple Working Conditions Based On Cloud Model

Under the background of "strengthening the protection of ecological environment in an all-round way and resolutely fighting the battle of pollution prevention and control",this paper conforms to the trend of energy-saving and environmental protection equipment manufacturing,takes a hybrid electric bus frame as the research object,combines finite element analysis,multi-area topology optimization based on load distribution,test design,dimension optimization considering robustness and reliability,and improved analytic hierarchy process based on cloud model.By means of weight determination and other methods,a set of lightweight forming process for bus frame is put forward.The main research contents and conclusions are as follows:Under the background of "strengthening the protection of ecological environment in an all-round way and resolutely fighting the battle of pollution prevention and control",this paper conforms to the trend of energy-saving and environmental protection equipment manufacturing,takes a hybrid electric bus frame as the research object,combines finite element analysis,multi-area topology optimization based on load distribution,test design,dimension optimization considering robustness and reliability,and improved analytic hierarchy process based on cloud model,A set of lightweight forming process for bus frame is put forward.The main research contents and conclusions are as follows:Finite element analysis of frame.Taking the original frame as the template and the principle of approaching the actual frame as far as possible,the finite element model of the frame is established.The model is put into five typical working conditions for static analysis.The safety factors of full load,acceleration,braking,turning and torsion are 2.8,2.9,2.8,1.8 and 1.6,respectively.There is surplus of safety factors in each working condition and there is room for optimization.Exploring the optimal topological structure of the frame.Aiming at the phenomena of centralized accumulation and hollowing of materials,a multi-area topology optimization based on load distribution is proposed.Variable density optimization method and optimization criterion algorithm are used to optimize the frame topology.According to the optimization results,the distribution of frame beams is determined and the model is rebuilt.Compared with the original frame,the quality of the new frame is reduced by 31 kg.Although the proportion of weight loss is small,a more reasonable layout scheme of frame materials is obtained,which provides a template for subsequent dimension optimization.Dimension optimization considering robustness.Fifteen parameters,which have great influence on the weight and performance of the frame,are selected by using the optimal Latin hypercube method as optimization objects and a deterministic optimization model of the frame is established.The deterministic optimization of the frame is carried out under various working conditions.The weight loss ranges of full load,acceleration,braking,turning and torsion are 22.8%,26.5%,26.1%,16.4% and 12.56%,respectively.By analyzing the quality level of the deterministic optimization results,it is found that the turning and torsion conditions do not meet the 6? quality level requirements,and the robust design is carried out.Under the premise of satisfying the requirement of 6? quality level,the weight reduction of turning and twisting conditions is 15.2% and 7.75%.An improved analytic hierarchy process based on cloud model is proposed to determine the working condition weights.Aiming at the problem of insufficient objectivity in determining the weights of current bus working conditions,the judgment scale constructed by "cloud model" and expert opinions gathered by "floating cloud" are used to obtain the judgment matrix.The weights of full load,acceleration,braking,turning and torsion are 43.9%,23.7%,18.5%,7.9% and 6% respectively.According to the weight coefficients of each working condition and the size optimization results of each working condition,the optimum weight under multiple working conditions is 840.79 kg,and the weight loss is 14.6%.The results are verified by finite element method and meet the requirements.In summary,this paper considers the reasonable material distribution,product output robustness and reliability,and weight factor distribution under multiple working conditions,and achieves the lightweight goal by lightweight design.It illustrates that a set of lightweight process for multi-working conditions of bus frame based on finite element analysis,topology optimization,robust size optimization and cloud model proposed in this paper is used for lightweight design of bus frame has certain reference significance.