Vibration-damping Characteristics Analysis Of Stand-off Layer Constrained Damping Structure

Passive constrained layer damping(PCLD)structure is often used in construction machinery for vibration and noise reduction.However,due to the limitations of traditional passive damping damping structures in the application of damping effects,a stand-off layer constrained damping structure with better vibration reduction effect came into being.The stand-off layer constrained damping structure is formed by adding "stand-off layer" between viscoelastic and base layers of PCLD.The basic idea is to increase the distance between the viscoelastic layer and the structural neutral surface by adding a stand-off layer.When vibrating,the stand-off layer is similar to the amplification of "lever",which can increase the shear deformation of the viscoelastic layer and improve the energy dissipation effect of the entire structure.At present,there are few dynamic model about the stand-off layer constrained damping structure,and most of them are based on the finite element analysis software to construct the model for simulation analysis.Although this method is simple to model and suitable for various boundary conditions,the introduction of more degrees of freedom leads to computational difficulties due to the fact that more grids are often divided in order to obtain higher accuracy,and the analysis of structural parameters and subsequent optimization are also more difficult.Therefore,it is very necessary to construct a dynamic model with high calculation accuracy,relatively few calculations,and easy optimization and analysis.With the support of the National Natural Science Foundation of China-Study on the Coupling Mechanism of Physical-mechanical Parameters of Tubular Interlaminar Stand-off Damping Structures,this paper studied the vibration-damping characteristics of the stand-off layer constrained damping structure through theoretical analysis and model building.The main contents of this article are as follows:1.Based on the Hamilton principle and the virtual work equation,a finite element dynamic model of the stand-off layer constrained damping beam was established.By comparing with the analysis results of existing literatures,the validity and correctness of the established model are verified,and the assumption that the stand-off layer can greatly improve the damping characteristics of the structure is further proved.Taking a cantilever stand-off layer constrained damping beam as an example,the influence of stand-off layer material selection and the structural-performance parameters on natural frequency and the loss factor of the structure is discussed.2.Based on Rayleigh-Ritz method and Love shell theory,the orthogonal eigenvalue polynomial function family constructed by Schmidt transform is used as a function of axial vibration mode function.The artificial spring is used to simulate various boundary conditions,and the stand-off layer constrained damping thin-walled cylindrical shell dynamic model is constructed.The research results show that the model has good accuracy and convergence.This paper discussed the effect of circumferential wave number on the vibration characteristics of stand-off layer constrained damping thin-walled cylindrical shells under various boundary conditions,and analyzed the influence of elastic modulus and thickness of the stand-off layer,viscoelastic layer and constrained layer on the natural frequency and loss factor of the structure by taking the stand-off layer constrained damping thin-walled cylindrical shell with simply-supported at both ends as an example.The research results of this paper can provide theoretical basis and research method for the design and optimization of the stand-off layer constrained damping structures in practical applications.At the same time,this theoretical method can provide a reference for the study of other damping structures.