Study On Vibration Modal Analysis And Dynamic Response Analysis Of395Diesel Engine

The engine block is the most complicated and the largest volume spare parts of the internal-combustion engine structure. It is the framework of the whole internal-combustion engine. With the development of high-speed, complex and lightweight on automobile, the power, volume and weight of the engine is required to improve. So it is particularly important to get the distribution of stress, deformation and dynamic characteristics of the block accurately in engine design stage, and it is very important for the design and improvement of the engine. Therefore, understanding the dynamic characteristics in-depth of the engine block, researching the relationship between the external forces and the inherent characteristics of the structure itself has become an essential important step from product development and design to structural optimization.Finite element method has become more mature with the development of computer science. It has been more and more widely used in almost all the field of engineering and machinery include internal-combustion engine. As a universal numerical analysis method, finite element method is one of the most reliable and efficient method for researching complex structure stiffness, strength etc. The components reliability is greatly improved due to the application of finite element technology in the engine, the research&development cost is reduced, the design cycle is greatly shortened, and the development of internal combustion engine industry is rapidly promoted.With the rapid development of science and technology, the study on dynamic characteristics of the block, especially the optimization and improvement of structure has not been widely applied in our country. The application of dynamic optimum design on structure is less in the actual project. In addition, in the process of structure optimization design and improvement, accurate finite element model cannot be fully utilized for follow-up research work at present. How to quickly and accurately solve the dynamic characteristic parameters of the block structure and optimize it by using the finite element model is still a difficult task.This article used395diesel engine as the research object, researched the important performance, structural strength and stiffness of the block using the finite element technology. In the entire research process, firstly, the geometric model of the block was established accurately used the3D modeling software according to the2D drawings of395diesel engine. Then the solid model was imported to the finite element analysis software, and the finite element model of the engine block was established successfully. Secondly, the static strength and stiffness was analysed by the finite element analysis technology. Considering the engine block is a complex structure assembly, it will be subjected to various forces in practical work. Through the theoretical calculation of the engine working process, a complete simulation of stress under static and explosion condition of the block structure was done in the computer using the calculated results, then the displacement and stress nephogram were drawn out under different conditions. Thirdly, the theoretical modal analysis of395diesel engine was carried out. The first six natural frequencies and mode shapes were obtained, and the stiffness weak areas of vibration on the block were analyzed. Finally, on the basis of modal analysis, the sensitivity analysis of the natural frequency and optimization design of the block was carried out. The weak areas of the structure on the block were optimized and the overall dynamic performance of the block was improved.In this paper the finite element method was applied to the study of the engine. Some valuable ideas and design basis were provided for the optimization design of the engine body and structure optimization of the old product block. At the same time, the beneficial attempt for the application of CAE technology in designing modern analysis engine was done. The basic idea proposed in this paper has universal significance. It is based on the dynamic characteristics and optimization design of the finite element model structure. It can solve the problem of dynamic optimum design on complex structures, have some engineering application value, can shorten the product Design&Development cycle effectively, and improve the efficiency of product development.