Research On High-static-low-dynamic Tortional Vibration Isolator For Ship Shafting

The isolation of low frequency torsional vibration is particularly important for the stability and safety ship shafting operation.The traditional shafting linear vibration isolator is difficult to meet the requirements of both high load and low-frequency vibration isolation.Aiming at the low frequency torsional vibration of the ship shafting,this thesis carries out the design of a torsional vibration isolator based on the parallel connection of positive and negative stiffness,and studies and analyzes the structure from the perspective of theory,simulation and experiment.The main work content of this thesis includes as follow:First of all,a ship shafting model is established and modal analysis is conducted by using the ANSYS Workbench software to verify that the shafting model conforms to the vibration characteristics of the ship shafting;The design and theoretical derivation of positive and negative torsional stiffness components for torsional vibration isolator are proposed based on the size of the shaft system model.A three-dimensional model of the torsional vibration isolator is constructed by using Solid Works software,and the relationship between the parameters of the isolator and torque output is studied.The parameter range of positive and negative torsional stiffness and the angle range of static equilibrium are determined under the condition of quasi-zero-stiffness.According to the test conditions,the structural strength is checked by using the statics structure simulation analysis of the ANSYS Workbench software.Secondly,a dynamic analysis is conducted on the high-static-low-dynamic torsional vibration isolator,and the torque transmissibility is obtained through the harmonic balance method.The influence of the stiffness ratio,damping ratio,and excitation amplitude of the isolator on the torque transmissibility is analyzed.By building the Simulink platform of the MATLAB for dynamic simulation,the fourth-order Runge-Kutta method is used to solve the dynamic response of the high-static-low-dynamic torsional vibration isolator and the equivalent linear vibration isolator under single frequency harmonic excitation,multi frequency harmonic excitation,and impact excitation,respectively.Furthermore,the simulation results show that the high-static-low-dynamic torsional vibration isolator designed in this thesis has better low-frequency vibration isolation effect.Finally,a prototype of high-static-low-dynamic torsional vibration isolator is developed,and a shafting torsional vibration test platform is built.By conducting static characteristic tests on highstatic-low-dynamic torsional vibration isolator,the torque and angle characteristic curves of the isolator are obtained,which is to verify the correctness of the theoretical analysis.By conducting dynamic characteristic tests,the dynamic responses under single frequency excitation and sweep frequency excitation are obtained,and compares with equivalent linear vibration isolator,it is verified that high-static-low-dynamic torsional vibration isolator designed in this thesis has better low-frequency vibration isolation effect.