Structural Parameter Identification And Structural Improvement Of Parallel Vibration Isolator With Positive And Negative Stiffness Based On Inclined Spring

Active vibration reduction system is an important equipment that provides a good antivibration environment for precision instruments and equipment.A prototype of an active damping system with high static stiffness and low dynamic stiffness had designed by using the principle of positive and negative stiffness in parallel before,However,the test data of the prototype showed that the vibration reduction system did not have good stability and failed to measure the low natural frequency.This thesis optimizes and improves its structure according to the above problems.The main research work and conclusions are as follows:1)The performance requirements of the active damping system are decomposed to obtain the requirements of the passive damping structure,and the principle of the scheme adopted by the active damping system on the passive damping structure and the existing structural design of the shock absorber are described.The parameters of the passive damping structure of the damping system are identified,and the existing problems of the existing passive damping structure are tested and analyzed.2)The model simplification and dynamic analysis of the parallel mechanism with positive and negative stiffness in the vertical direction of the vibration damping system are carried out,and the reason why the low frequency of the vibration damping structure cannot be measured is qualitatively analyzed.The transient structural analysis module(Transient Structural)in the ANSYS software tool is used to analyze the influence of different structural parameters on the vertical vibration.The simulation data shows that the shaft-hole friction coefficient at the torsion hinge has the greatest effect on the vertical vibration,and the friction coefficient at the sliding guide bar has almost no effect on the vertical vibration.Based on the analysis results,the structure was optimized and improved,and the feasibility analysis of the modified structure was carried out.3)The experiment verifies the stability of the pendulum to support the weight alone.The dynamic modeling and analysis of the three-spring mechanism are carried out,and the yaw frequency is calculated,The results show that the deflection frequency of the three-spring mechanism is relatively close to the natural frequency in the vertical direction.The original structure is improved to restrain the yaw movement of the three-spring mechanism.Using ANSYS software tools,a dynamic simulation of the vibration reduction system before and after the structural improvement was carried out to verify the effectiveness of the structural improvement.4)The improved damping system was integrated and assembled,and a test platform was built.The natural frequency and damping rate of the shock absorber were measured by using the time-domain waveform diagram,which verified the effectiveness of the structural improvement.Using the test platform,the vibration transmission rate of the shock absorber was measured to verify the damping performance of the passive vibration isolation of the shock absorber.