Research On Improvement Design Of Noise Radiation Key Structure Of Diesel Engine

The vibration and noise are important parameters for the diesel engine's performance, the research on improving its vibration and noise radiate level by structural optimization is an important aspect in the diesel engine's development proeess. Because of especial purpose and construct, the block and oil pan of diesel engine have been the major radiation components. Controlling the transfer function of the key fexture is one of the method that control the diesel engine's vibration and noise. Meanwhile, as the most suitable technology for continuous body in structural optimization areas, topology optimization design can receive the optimal distribution of materials based on improving or keeping the structure performance,and achieve the reduction of design cycle and cost.Based on the 90°V8 diesel engine's block and oil pan, series of studies are carried out on minimize the structure quality and inhibite the structure radiation are done by using the finite element method and topology optimization technology. In detail, the main work is as follows:(1) The development of the structural topology optimization design and its application in.the field of car are checked firstly, then the calculation method of topology optimization technology and its technical line are studied. At last, the key problems that need to solve in this paper are decided.(2) The entity model of diesel engine's block and oil pan are established by using the feature modeling technology on the platform of I-DEAS software. Based on the convergence analysis of discrete errors,the block and oil pan's finite element models are established. Adopting the Lanczos method, their modal computations have been conducted, and the natural frequencies and mode shapes are obtained which establish the base to optistruct the structures.(3) According to the actual size and boundary condition,the topology optimized model of diesel engine's block and oil pan are established on the Optistruct module of HyperWorks software. Then, Based on the oil pan whose construct is simple relatively, times of topology optimized calculation have done on the premise of minimize the quality and maximize the frequencies by using the artificial density method. Through the calculations, the scheme of how to set up the design variable, objective function and constraint function of structure topology optimization are achieved. At last, the scheme are applied to the diesel engine's block, and the optimal distribution of materials which meet the design requires are achieved.(4) By feature modelling technology,the diesel engine's block and oil pan are rebulid according to the topology optimized results. The modal analysis results of the new structure display that the lower frequencies have degree of increased. The new construction of diesel engine's block and oil pan sacrifice the design requires that minimize the quality and increase the frequency basically.