| Summary: | 碩士 === 遠東科技大學 === 機械研究所 === 98 === One of the key factors in designing a motor-built-in high speed spindle is to assemble the rotor-shaft by means of hot-fit. This thesis presents a study of the influence of the hot-fit rotor on the local stiffness of the shaft. In a previous study, the optimization approach was recommended by introducing equivalent Young’s modulus characterizing the effects on the local stiffness of the shaft. The approach, being verified by modal testing, is a posterior measure. In present study, dynamic analyses of the hot-fit rotor-shaft assembly using contact elements are conducted. The normal contact pressure between the rotor and the shaft is obtained through the use of contact elements. The stresses distribution between them is then available thereafter. The effect of pre-stress are then adopted for subsequent finite element modal analyses. The finite element modal analysis results are verified by the experimental modal testing and theoretical formulation. Because the finite element model proposed in this study is constructed using solid elements, it takes more computational time to obtain the frequency response function. Therefore, in this study the equivalent direct modeling with line elements is also established by using the method of optimized modification of equivalent Young's modulus with the results of finite contact element analysis. The validity of this equivalent direct model is also verified in this thesis.
The results obtained from this study indicated: it can be accurate and effective in analyzing the dynamic behavior of the rotary shaft system with hot-fit components by using contact elements, and then the enhanced local shaft stiffness at the location of rotor mounted on the shaft of equivalent direct model by using optimized equivalent Young's modulus such that the complexity of finite element model and the time required for analysis can be reduced when the simplified direct model is applied subsequently to the rotor dynamic analysis.
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