Research On Power Flow Transmission Of Inclined Isolation System

Vibration and noise control possess an very important value in scientific research in theoretical and practical engineering. Vibration isolation is the most investigated and applied in all kinds of vibration control technology, and inclined isolation system are widely used in automotive industry, for it has a greater transverse stiffness, and it can lower the center of gravity of the isolation system. To investigate the dynamic transmission mechanism of the flexible isolation system from the viewpoint of vibration energy is one of the leading research issues in the field of vibration and noise control. The isolator is modeled as elastic component, Euler beam and Timoshenko beam respectively in this thesis, and the power flow characteristics of the complicated mechanical system's dynamic on flexible foundation are studied.The vibration-coupling characteristics of the inclined isolation system are studied, the decoupling condition of the transverse-roll coupled vibration is obtained. A generalized theoretical model for multiple-degrees-of-freedom vibration analysis of isolation system with inclined elastic components is developed. The transfer matrixes of the force and velocity of each joint are given. The dynamic expression of the sub-system is derived, and the expression of power flow transmission is presented. It is founded that with the inclination of the mounts increases the power flows though the vibration source and foundation decrease in the medium-high frequency domain and in the low frequency domain the transverse resonant frequency increase while the vertical and rolling resonant frequency decrease.In order to reveal the stand wave effect of the isolator in high frequency domain, longitudinal vibration mobility and transverse vibration mobility of Euler beam are derived and the dynamic characteristic transfer matrix and the power flow expression of the isolation system are obtained base on the Euler beam theory. The effects of the stiffness and damping of the isolator or the foundation on the power transmission are studied. The power flows of the isolation system with the standing wave effect of the isolator or not are compared. It is founded that the standing longitudinal wave and the standing flexural wave in the mount are the main reason why prominent peak of the power flow transmmit into the base appears in high frequency domain. At the same time, ANSYS analysis software is used to validate the accuracy of system mode and modeling method. It can draw a conclusion that the constructed model is correct by comparing theory results to finite element analysis ones.The isolators are modeled as Timoshenko beam when the shear effect and the moment of inertial of the beam are considered. Longitudinal vibration mobility and transverse vibration mobility of Timoshenko beam are derived; the dynamic characteristic transfer matrix and the power flow expression of the coupling isolation system are presented considering the wave effect of the isolators. It is founded that the shear effect and moment of inertial of beam decrease the power transmitted into foundation in the medium-high frequency domain, while have little effect of the power transmission in the low frequency domain, also the first natural frequency of isolation decreases which means standing wave effect appears in advance.Various anasys methods of Mechanical models of isolator are studied in this thesis, and the results obtained can illustrate the problems and phenomena that the traditional isolation system can not explain, and also provide effective references for vibration isolation design in engineering practice.