Bending Vibration Mechanics Of The Disc Rod Rotor-bearing System Based On Non-continuous Characteristics

With the development of gas turbine techniques, disc-type rod fastening rotor is getting use. Its major structural characteristics are that a rotor is not continuous and not integral, this causing the rotor type to present different vibration characteristics from general continuous and integral rotors. At present, study on rotor dynamics mainly focuses on continuous and integral rotors. When calculating vibration characteristics, disc-type rod fastening rotors are often regarded as continuous integral rotors or correction is conduced with a stiffness modified coefficients. The results from doing so are not satisfactory. So it is necessary to make a further study on this subject.In view of the structural characteristics that a disc-type rod fastening rotor is not continuous and not integral, we put forward several basic mechanical assumptions for coupling and contact points of disc-type rod fastening rotors. We establish a bond graph coupling dynamic analytical model for disc-type rod fastening rotors based on the application of bond graph modal analysis method to bending vibration modal analysis for continuous beam and in combination with mechanical assumptions. With this model, we perform theoretical calculation for a experimental rod fastening rotor and comparison between the calculation result and measurement result shows that the calculation result agree with the measurement result well, the calculation accuracy is improved to a great extent in comparison with the previous calculation with the model for continuous and integral rotors or stiffness modified coefficient method. In addition, the comparison between various calculation results also shows that the structural characteristics of disc-type rod fastening rotors results in a reduced natural frequency and such frequency is sensitive to equivalent bending stiffness on inter-contact contact surface. After further considering bearing effect, we establish a dynamic analytical model for bearing system for disc-type rod fastening rotors. The calculation shows that the structural characteristics of disc-type rod fastening rotors influence its critical speed in such way with natural frequency and its critical speed is lower than the one of continuous integral rotor-bearing system with the same size.The above study solve the problem how to improve the vibration characteristics computational accuracy for disc-type rod fastening rotor-bearing system in engineering practice and therefore has significant application value.