An equivalent direct modeling of a rotary shaft with hot-fit components using contact element modal analysis results

One key factor in designing a motor built-in high-speed motor spindle is to assemble the motor rotor and shaft by means of hot-fit. In a previous study, the optimization approach was recommended by introducing an equivalent local Young’s modulus characterizing the effects on the local stiffness of the shaft at the location of hot-fit. This approach, being based on the modal testing results, is a posterior improvement. In this paper, contact pressure between the rotor and the shaft is firstly calculated through contact theory. The stress state is thus determined. The contact element modal analysis then follows with the stress state as a pre-stressed condition. The effects of pre-stress are then adopted for subsequent contact element modal analysis. The accuracy and the validity of the finite element results are verified by modal testing. Finally, an equivalent direct modeling is suggested as an efficient alternative. This equivalent model is constructed with line elements and the model is created based on the results obtained from the contact element modal analysis. The results obtained from this study indicate that the equivalent direct model with line elements is accurate and efficient in analyzing the dynamic behavior of a rotary shaft system with hot-fit components.