Research On Beem Type Dynamic Vibration Absorberfor Subway Wheels

While urban rail transit brings convenience to people's travel,it also produces a lot of noise pollution,which brings some inconvenience to people living along the track.The dynamic vibration absorber with beam structure has been widely used in engineering field because of its low cost,convenient installation and maintenance,and the ability to reduce vibration in multiple frequency bands.In this paper,the vibration characteristics of the dynamic vibration damper with constrained damping beam structure are studied.Combined with the vibration characteristics of the Sshaped grid subway wheel,two wheel dynamic vibration absorbers with good vibration and noise reduction performance are designed.The beam structure is selected as a wheel dynamic vibration absorber depending on the shape of the wheel.Based on the Euleranuli beam bending deformation theory,the vibration characteristics of the beam are analyzed and the finite element model of the beam vibration is obtained.The energy dissipation characteristics of viscoelastic damping are analyzed based on the complex modulus model,and the influence of viscoelastic damping parameters on energy consumption is obtained.The theory of constrained damping treatment is studied.The relation expression between loss factor and system parameters under one-sided constrained damping is obtained.The influence of parameters on natural frequency and modal loss factor under constrained damping is simulated.According to the theory of single-degreeof-freedom damped dynamic vibration absorber,the influence of various parameters on vibration damping performance is analyzed.The finite element simulation and experimental test of the wheel mode are carried out.The wheel modal frequency and mode shape are obtained.The law of wheel vibration is summarized and the axial vibration and radial vibration characteristics of the wheel are analyzed.The design experiment measured the vibration response and noise sound pressure level of each position of the wheel under axial or radial excitation.The principle of modal modal identification of rational fractional polynomial method is analyzed.The application of rational fractional polynomial method in modal parameter identification is realized by MATLAB programming,which is beneficial to determine the equivalent modal parameters at the installation point of dynamic vibration absorber.Power absorber.Comparing the wheel and disc modes,the wheel is equivalent to the disc structure,and the disk vibration finite element model is built by the mindlin plate unit.According to the power flow method,the coupled vibration model of the damper beam and the disc structure is established.It is theoretically analyzed that the damper beam is used as the dynamic vibration absorber for the axial vibration absorption of the disc structure,and it has the full-band vibration absorption effect.Then,through experiments,the effects of the number of vibration absorbers,the type of vibration absorbers,and the combination of different types of vibration absorbers on the vibration damping performance of the disc structure were investigated.According to the theoretical analysis and experimental results,the installation point position of the beam dynamic vibration absorber is determined by considering the size parameters of the wheel,and the equivalence polynomial method is used to identify the equivalent modal parameters of the installation point.Two kinds of beam dynamic vibration absorbers are designed to meet the requirements,and the vibration and noise reduction effects are tested.The results show that the vibration absorbers A and B can reduce the radiation noise of the wheel under axial and radial excitation.At the same time,two kinds of dynamic vibration absorbers can reduce the axial vibration radiation noise by 15 dB and the radial vibration radiation noise by 10 dB.