Research On Performances Of Conical Particle Damping And Its Characteristics In Rotating Environments

As a passive control damping technology,particle damping technology,has been widely used in various fields.The technology is mainly to attach a closed cavity with a certain number of particles to the vibrating structure.This technology use the collision and friction between the particles and between the particles and the cavity wall to lose vibration energy.so as to suppress the vibration of the structure due to external excitation.Its damping frequency bandwidth,simple structure,good effect,can adapt to harsh working environment,has broad research prospects.However,due to the limitation of the existing damping mechanism of particle damper,it loses energy dissipation effect and damping effect in centrifugal environment.Based on the discrete element method,this paper studies the pressure distribution of the particle layer in different cavity structures.It is found that the pressure of the particle layer in the cylindrical cavity increases gradually with the depth until it tends to be stable.In the conical cavity,the pressure of particle layer first increases and then decreases with the increase of depth,which will make the particles in the conical cavity easier to participate in the vibration reduction of the structure,so as to improve the damping characteristics of the structure.Using this characteristic,the conical particle damper is applied to the rotating environment,which is helpful to improve the vibration reduction performance of particle damper in this environment.Therefore,this study can expand the application range of particle damping and has important engineering significance.In this research,the relationship between the stress distribution and the depth of the particle layer in the cylindrical and conical cavities is analyzed according to the continuity hypothesis theory.It is found that the shape of the cavity structure will affect the pressure distribution between the particle layers,and then affect the vibration reduction effect of the particle damping.Then,the cylindrical particle damping linear contact model is constructed by using the discrete element method,and the effectiveness of the model is verified by experimental comparison,and the conical particle damping discrete element model is established.On this basis,the effects of filling ratio,volume ratio(single particle volume / cavity volume)and wall inclination angle of conical cavity on the damping characteristics of conical particles are analyzed.The results show that the optimal filling ratio of conical particle damping is 0.6,and the inclination angle of conical cavity wall has no effect on the optimal filling ratio.At the same time,the damping performance of cylindrical particle damping and conical particle damping is compared under the same filling ratio.When the filling ratio is less than 0.6,the damping effect of conical particle damping is obviously better than that of cylindrical particle damping because more particles participate in collision energy dissipation,which is consistent with the theoretical analysis.In addition,through calculation,it is found that the optimal wall inclination of conical particle damping cavity is 45 ° to 55 ° and the optimal volume ratio is 0.00032.Under the rotating environment,the particles in the cavity will be pressed together due to the centrifugal force,and the particles will move with the structure,resulting in the failure of energy dissipation mechanism caused by friction.Compared with the cylindrical particle damper which is a conventional particle damper,because of its structural characteristics,the closer the conical particle damper is to the bottom,the smaller the increase of the positive pressure between the particle layers caused by centrifugal force.In this paper,by comparing the effects of the filling ratio and volume ratio on the damping characteristics of the conical and cylindrical particles at the rotation speed of 0-5s-1,it is found that the conical particle damping is different at different rotation speeds Therefore,the vibration reduction characteristics and failure mechanism of conical particle damping in rotating environment were studied.The results show that with the increase of rotation speed,the optimal filling ratio of particle damping decreases and the optimal volume ratio increases.In the rotating environment,the optimal chamber wall inclination is changed from 45°-55° to 70°-75°,and the optimal chamber wall inclination does not change with the change of rotating speed.This study provides a theoretical basis for the design of conical particle damping under rotating conditions.