Mode And Finite Element Analysis Of The Centrifugal Pump Bearing Bracket

With the development of technology and industry , machines have become more speedy and light and the environment of mechanical structure becomes more complex ,so the vibration problem of structures has drawn people's attention ,even worse ,vibration has arose serious accident, statistics materials show that 40 percent of aircraft accidents are related with vibration, as to our country's thermal power generating units, very serious accidents which vibration is the main factor have happened more frequently within 20 years. Vibration problems have emerged not only in the industrial section such as aviation and electric power, but also in the fields like spaceflight, mechanism, architecture, water conservancy and traffic. The vibration will produce many side effects: intensive vibrations will affect the normal work of instruments and meters; they affect workers' comfort and environment; they endanger the safety and reliability of mechanical structures; they also affect the product's function and quality. These kinds of accidents not only lead to large economy loss, but also bring bad social influence. They also increase the workers psychological pressure.The mechanical structure design improves with the development of technology and society, it had developed from empirical design to the combination between design and mechanical analysis, up to modern optimized design of structure, but as to strength, the structure design is still based on static criterion, then measures are adopted to control the vibration level, even the serious vibration problems have come out. Practice has proved that this method is costly and less effective. thus, the traditional mechanical structure design method based on static criterion can't meet the needs of modern product design, as to the structure which endures dynamic load, dynamic design method is an effective method as to modern product design because it can control the vibration level of mechanical structure, improve the quality of product, increase its reliability and so on. This dynamicmethod suits the direction of design technology of mechanical structure. The dynamic design is defined as: at the design stage, the structure is designed according to the function, strength and the dynamic environment, the structure has excellent dynamic property and our purposes which control the vibration level are achieved.Centrifugal pump bearing bracket is a key components of the centrifugal pump. The old centrifugal pump bearing bracket was a complex load system. It stood loads from the bearing. If we analyzed the intensity and toughness or dynamics with the classical mechanics, we must do some simplifications and hypothesis, resulting in lengthy operation and even impossible calculation. Thus we held a blindness of design work and affected the structural reasonability and weight all the time. We could analyze the stress and strain of the complex structures with the finite element method .It could conduce to the designer to review the intensity and toughness of the structural components of the whole old bracket and guide the design, production and manufacture. At the same time it also could optimize the structure and improve the mechanical capability of the whole pump, have the usable values for shortening the cycles of the exploitation of the product and lowering the cost of exploitation. This could accelerate its application in our domestic markets and lay the solid foundation for the entrance to the international markets.This paper is going to do some researches on simplifying the structure of the old centrifugal pump bearing bracket, dealing with the pre-post finite element, solving it and improving the structure with the ANSYS software. Carry on the static analysis,the modal analysis and the transient analysis to the old bearing bracket.A precise and reliable finite element model was the foundation of finite element analysis. The preciseness of the analyzing result of the finite element was decided by the preciseness of the calculating model. But there were many all kinds of shapes in the practical engineering problem. We should do some simplifications.Without them, this kind of finite element analysis could become difficult, even impossible.First, we should digest and absorb the technical drawing. On the condition of finite element knowledge, according to the tank structure and the loading characters, we established the calculating model with elements as simple as possible on the premise of reflecting the mechanical characters and reducing the expenditure of computation. The paper adopted the solid element and beam element to establish the 3D finite element of Centrifugal pump bearing bracket. Solid elements were used to the bearing bracket. The Beam elements were used to shaft and the simplified bearing. We must do some simplified measure because the complexity of the old bearing bracket. The simplified degrees were depending on the analyzing purpose. On the condition of unaffected the whole intensity and toughness, the screw thread hole of the old bearing bracket body are transform to hole and chamfer were omitted. After the model established, we confirmed load conditions, applied load on the model, restricted the boundary condition, calculated and analyzed the result.Second, after analyzing the results, we ameliorated and perfected the small components whose performances of intensity and toughness were poor .So another analysis was done to analyze the result of improved structure.