Study On Vibration Reduction Of A Cantilever Dynamic Vibration Absorber For Rotating Machinery

Dynamic vibration absorber is a research hotspot in the field of structural vibration control.Its basic working principle is to change its natural vibration characteristics by adjusting oneself structural physical parameters.The characteristic of the research in this stage is to use the control unit to realize the semi-active tracking of the main absorber by the vibration absorber,and to reduce the main system vibration in the larger frequency bandwidth.Aiming at the problem that the traditional vibration absorber has narrow effective absorption bandwidth and the variable mass absorber easily introduces non-linear factors,this paper proposes a linear variable stiffness FM vibration absorption structure-round section cantilever type dynamic vibration absorber,which can be rotated by attaching a cantilever beam The circular cross-section mass is used as a variable stiffness unit to change the feed distance at different positions on the cantilever beam,and tune the overall stiffness of the vibration absorber,ultimately achieving the energy dissipation in the first-order critical resonance area of the rotor system to be reduced,and improving the rotor.Structure effective working speed bandwidth.The main content of this paper's research is as follows:Firstly,the basic principles of the traditional dynamic vibration absorber were analyzed is based on the theory of vibration mechanics,including the P and Q fixed point theory and the parameters optimization theory of the vibration absorber.Through the simulation analysis of Matlab,the structural parameters of the cantilever-mass coupling vibration-absorbing system were changed to the main system.Secondly,a variable stiffness cantilevered dynamic vibration absorber with circular cross section was proposed.The vibration absorption principle of the cantilever type variable stiffness dynamic vibration absorber was analyzed and its three-dimensional structure model was designed.Using the Simulink simulation model to dynamically describe the natural frequency of the vibration absorber close to the forced vibration frequency of the main system will increase the vibration amplitude of the vibration absorber subsystem.Shows the theoretical feasibility of using the absorber to dissipate energy of the first order critical resonance of the rotor system.Thirdly,solving the natural frequency of each mode of the coupled structure of the cantilever type dynamic vibration absorber,by changing the distance of the mass at different positions on the cantilever beam,it can be determined that the first-order natural frequency bandwidth range of the cantilever type dynamic vibration absorber can be widened.Improve the adaptability to vibration damping of rotor mechanical shafting.Fourthly,this three-dimensional model of the main vibration system of the cantilever vibration absorber subsystem-rotor system was established.The finite element mesh of the three-dimensional model of the single-span rotor system was established using Ansys,and its finite element model was established.Then the dynamic Modal analysis of this structure was performed.We obtained the first four-order restrained mode vibration mode of the single-span rotor shaft system with Harmonic analysis,and found the maximum displacement response point of the rotor shaft system under the forced vibration response.Judging the use of the vibration absorber can achieve the critical vibration energy dissipation effect.Finally,the experimental test system for a rotor device was set up to test and verify whether the variable stiffness dynamic vibration absorber can eliminate the energy of the rotor system.According to the design size,the corresponding circular cross-section cantilever mass dampers are obtained.By changing the mass position on the cantilever beam to change its equivalent stiffness and natural frequency,the energy dissipation and damping process of thefirst-order critical speed of the rotor system is realized.Then a multi-vibration absorber was built to perform energy dissipation and vibration absorption studies on the rotor table to verify the optimal energy dissipation and vibration reduction effect on the rotor system.The experimental results show that the dynamic vibration absorber can perform energy dissipation and vibration absorption in the range of 48Hz-61 Hz as the mass changes at different positions on the cantilever beam,but the energy dissipation and vibration reduction effect is best at the first-order critical rotation speed.The vibration amplitude of the system is reduced by about14.5dB,which means that the dynamic vibration absorber can realize the energy dissipation and vibration reduction effect of the rotor system.The installation method and the design ruler shape can provide reference for subsequent research.