Research On Finite Element Model Updating Of Large Mechanical Equipment Gear Transmission System

With the improvement of mechanical design level, the transmission system of large mechanical equipment is becoming more and more complex in the structure and function. And the unreasonable design could produce vibration in the system, which leads to a result of mechanical equipment can’t work normally. Thus, in order to avoid unnecessary losses, the vibration problem of mechanical transmission system should be analyzed in simulation and the result of vibration analysis should be optimized to some extent, which is a key technology of improving overall dynamic performance of mechanical equipment. An accurate finite element model(FEM) is very important for the dynamic design of structure. Thus improving the accuracy of FEM to describe the actual situation accurately has important significance on guaranteeing the overall dynamic performance of mechanical transmission system. The purpose of this paper is to study the finite element modeling, model updating and parameter identification of mechanical transmission system by means of combining finite element simulation analysis with experimental test.The modeling method of torsional vibration normalized model of typical large mechanical transmission system is studied. And the determination methods of moment of inertia and torsional stiffness in the FEM are presented, such as the calculation of torsional stiffness of coupling and gear pair in finite element software. Then, the methods are applied to a transmission system of 9 meters mill. And the modal analysis is carried out to obtain the natural frequencies and modal vibration shapes.The technique of finite element model updating based on response surface method is studied. The example of updating for FEM of stator structure of rod-type ultrasonic motor shows that this method has effectiveness in the problem of containing uncertainty issues and the response surface model has the advantage of running fast. In addition, according to the problem of avoiding resonance in a 7.9 meters mill, the FEM of its transmission system is updated and optimized based on this method, and its modal frequency is adjusted to avoid the working frequency. Finally, the optimization of transmission system is achieved, which indicates this method has reference value to the design of transmission system.Based on the theory of similarity design of gear transmission system, a similar experimental device of large mechanical equipment transmission system is developed. According to this device of transmission system, the entity bending-torsion FEM is building. Then, the uncertain parameters in the model are identificated by model updating to obtain a high-accuracy FEM based on the experimental results. At last, the dynamic response calculation is carried out to the FEM as the theoretical basis for subsequent analysis.