scholarly journals Vibration and Damping Analysis of a Multilayered Composite Plate with a Viscoelastic Midlayer

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Haochuan Wan ◽  
Yinong Li ◽  
Ling Zheng
Keyword(s):  
Loss Factor ◽  
Structural Vibration ◽  
Viscoelastic Materials ◽  
Optimum Frequency ◽  
Complex Constant ◽  
Multilayered Plates ◽  
Structural Loss ◽  
Complex Structural ◽  
Constrained Damping ◽  
Constrained Materials

Based on the theory of Donnell and Kirchhoff hypothesis and by using the complex constant model of viscoelastic materials, the vibration equations of five-layered constrained damping plate are established. The transfer matrix method (TMM) is improved and used to solve equations. The improved TMM is more effective to solve complex structural vibration. The influence of layer numbers, thickness of each layer, and arrangement of materials on vibration behavior are discussed. It is proved that multilayered plates can more effectively reduce natural frequency and obtain higher structural loss factor. The loss factor increases with the number of whole layers. Symmetrical structure can obtain higher structural loss factor than one-direction structure. Uniform arrangement of viscoelastic materials and constrained materials can obtain higher structural loss factor than nonuniform arrangement. There is different optimum frequency with different material thickness, and the optimum frequency is not dependent from layer numbers.

Thickness Optimization Study of Constrained Damping Plate

2012 ◽  
Vol 226-228 ◽  
pp. 436-439
Author(s):  
Hao Chuan Wan ◽  
Ling Zheng ◽  
Yi Nong Li
Keyword(s):  
Natural Frequency ◽  
Loss Factor ◽  
Added Mass ◽  
Structural Vibration ◽  
Viscoelastic Layer ◽  
Thickness Optimization ◽  
Damping Effect ◽  
Optimization Study ◽  
Constrained Damping ◽  
The Relationship

Based on Kirchhoff hypothesis, the vibration equations of constrained damping plate are established and the equations are solved. Influence of the thicknesses of constrained layer and viscoelastic layer on structural vibration character are analyzed, the curves of natural frequency and loss factor with different thicknesses of viscoelastic layer and constrained layer are obtained. The figures indicated that it is not the more thickness of the viscoelastic layer and constrained layer the higher of the loss factor. Both of the thicknesses have optimum values, which are interact. The relationship between of loss factor and added mass is investigated. The results show that various thickness plans can obtain the same loss factor but very different added mass. So it is very necessary to optimize the thickness of viscoelastic layer and constrained layer to obtain the best damping effect.

Foil Gas Bearing With Compression Springs: Analyses and Experiments

2007 ◽  
Vol 129 (3) ◽  
pp. 628-639 ◽  
Author(s):  
Ju-ho Song ◽  
Daejong Kim
Keyword(s):  
Loss Factor ◽  
Load Capacity ◽  
Underlying Structure ◽  
Equivalent Viscous Damping ◽  
Foil Bearings ◽  
Foil Bearing ◽  
Different Types ◽  
Structural Loss ◽  
Compression Springs ◽  
Gas Bearing

A new foil gas bearing with spring bumps was constructed, analyzed, and tested. The new foil gas bearing uses a series of compression springs as compliant underlying structures instead of corrugated bump foils. Experiments on the stiffness of the spring bumps show an excellent agreement with an analytical model developed for the spring bumps. Load capacity, structural stiffness, and equivalent viscous damping (and structural loss factor) were measured to demonstrate the feasibility of the new foil bearing. Orbit and coast-down simulations using the calculated stiffness and measured structural loss factor indicate that the damping of underlying structure can suppress the maximum peak at the critical speed very effectively but not the onset of hydrodynamic rotor-bearing instability. However, the damping plays an important role in suppressing the subsynchronous vibrations under limit cycles. The observation is believed to be true with any air foil bearings with different types of elastic foundations.

scholarly journals Microstructural Topology Optimization of Constrained Layer Damping on Plates for Maximum Modal Loss Factor of Macrostructures

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Zhanpeng Fang ◽  
Lei Yao ◽  
Shuxia Tian ◽  
Junjian Hou
Keyword(s):  
Topology Optimization ◽  
Loss Factor ◽  
Strain Energy ◽  
Design Method ◽  
Optimization Method ◽  
Constrained Layer Damping ◽  
Viscoelastic Materials ◽  
Modal Strain Energy ◽  
Design Variables ◽  
Microstructural Topology Optimization

This paper presents microstructural topology optimization of viscoelastic materials for the plates with constrained layer damping (CLD) treatments. The design objective is to maximize modal loss factor of macrostructures, which is obtained by using the Modal Strain Energy (MSE) method. The microstructure of the viscoelastic damping layer is composed of 3D periodic unit cells. The effective elastic properties of the unit cell are obtained through the strain energy-based method. The density-based topology optimization is adopted to find optimal microstructures of viscoelastic materials. The design sensitivities of modal loss factor with respect to the design variables are analyzed and the design variables are updated by Method of Moving Asymptotes (MMA). Numerical examples are given to demonstrate the validity of the proposed optimization method. The effectiveness of the optimal design method is illustrated by comparing a solid and an optimized cellular viscoelastic material as applied to the plates with CLD treatments.

Topology Optimization for Constrained Layer Damping Plates Using Evolutionary Structural Optimization Method

2014 ◽  
Vol 894 ◽  
pp. 158-162 ◽  
Author(s):  
Bing Qin Wang ◽  
Bing Li Wang ◽  
Zhi Yuan Huang
Keyword(s):  
Topology Optimization ◽  
Energy Dissipation ◽  
Structural Optimization ◽  
Design Variable ◽  
Loss Factor ◽  
Optimization Approach ◽  
Constrained Layer Damping ◽  
Modal Strain Energy ◽  
Evolutionary Structural Optimization ◽  
Constrained Damping

The evolutionary structural optimization (ESO) is used to optimize constrained damping layer structure. Considering the vibration and energy dissipation mode of the plate with constrained layer damping treatment, the elements of constrained damping layers and modal loss factor are considered as design variable and objective function, while damping material consumption is considered as a constraint. The sensitivity of modal loss factor to design variable is further derived using modal strain energy analysis method. Numerical example is used to demonstrate the effectiveness of the proposed topology optimization approach. The results show that vibration energy dissipation of the plates can be enhanced by the optimal constrained layer damping layout.

Dynamic analysis of viscoelastic tuned mass damper system under harmonic excitation

2019 ◽  
Vol 25 (11) ◽  
pp. 1768-1779 ◽  
Author(s):  
Jun Dai ◽  
Zhao-Dong Xu ◽  
Pan-Pan Gai
Keyword(s):  
Frequency Dependence ◽  
Natural Frequency ◽  
Storage Modulus ◽  
Primary Structure ◽  
Loss Factor ◽  
Design Strategy ◽  
Tuned Mass Damper ◽  
Optimum Frequency ◽  
Mass Damper ◽  
And Control

The purpose of this paper is to investigate the contribution of viscoelastic material (VEM) to the control performance of the viscoelastic tuned mass damper (VTMD). Firstly, the equivalent fractional derivation Kelvin model is used to describe the frequency dependence of viscoelasticity in VTMD, and an index is proposed to characterize the level of frequency dependence. Then the effects of the high loss factor of VEM and frequency dependence of viscoelasticity on the effectiveness and robustness of VTMD control are analyzed by numerical examples. At last, a design strategy for VTMD is proposed to select the type of VEM and optimize its stiffness contribution. The results show that the frequency dependence of shear storage modulus of VEM is beneficial to further reduce the dynamic response of the primary structure equipped with VTMD, and the loss factor of VEM determines the optimum frequency ratio and control effect of VTMD. Compared to the conventional tuned mass damper, VTMD has a better robustness for the positive error of the natural frequency of VTMD but has a worse robustness for the negative error. The frequency dependence of shear storage modulus of VEM is beneficial to the robustness of VTMD for both the positive and negative errors of the natural frequency of the primary structure. The VEM with a strong frequency dependence of shear storage modulus is the ideal VEM for VTMD, and the proposed design strategy can deal with the trade-off between the control effectiveness and control robustness of VTMD.

scholarly journals Research on the Multilayer Free Damping Structure Design

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Jie Meng ◽  
Dagang Sun
Keyword(s):  
Mathematical Model ◽  
Layer Thickness ◽  
Loss Factor ◽  
Structure Design ◽  
Thickness Ratio ◽  
Design Solution ◽  
Change Rate ◽  
Layer Thickness Ratio ◽  
Structural Loss ◽  
Damping Materials

The aim of this paper is to put forward a design model for multilayer free damping structures. It sets up a mathematical model and deduces the formula for its structural loss factor η and analyzes the change rules of η along with the change rate of the elastic modulus ratio q1, the change rate of the loss factors of damping materials q2, and the change rate of the layer thickness ratio q3 under the condition with the layer thickness ratio h2=1,3,5,10 by software MATLAB. Based on three specific damping structures, the mathematical model is verified through ABAQUS. With the given structural loss factor (η≥2) and the layer number (n=3,4,5,6), 34 kinds of multilayer free damping structures are then presented. The study is meant to provide a more flexible and more diverse design solution for multilayer free damping structures.

scholarly journals Vibration suppression analysis and experimental test of additional constrained damping layer in space science experiment cabinet

2021 ◽  
Vol 30 ◽  
pp. 2633366X2097865
Author(s):  
Haitao Luo ◽  
Siwei Guo ◽  
Changshuai Yu ◽  
Jia Fu ◽  
Haochen Wang ◽  
...  
Keyword(s):  
Experimental Test ◽  
Loss Factor ◽  
Vibration Suppression ◽  
Resonance Region ◽  
Space Science ◽  
Vibration Level ◽  
Acceleration Response ◽  
Simulation And Experiment ◽  
Suppression Mechanism ◽  
Constrained Damping

Aiming at the problem that the vibration of the space science experimental cabinet is too large during the launch phase of the rocket, the viscoelastic constrained damping layer is used to suppress the vibration. Firstly, to explore the vibration suppression mechanism of the constrained damping layer, the dynamic model of the constrained damping layer is established and the modal loss factor is calculated. Secondly, the influence of the modulus, material thickness, and the position and the area of the damping layer on the loss factor of the structure is analyzed. Finally, the simulation and experiment methods are used to calculate and verify the space science experiment cabinet with additional constrained damping layer. The results show that the viscoelastic constrained damping can effectively reduce the vibration level of the space science experiment cabinet, and the acceleration response in the resonance region is reduced by more than 56%. The viscoelastic constrained damping structure is simple and easy to realize, which can suppress the vibration of the space payload design is of great significance.

Topology Optimization of Constrained Damping Layer Treatments

2002 ◽  
Author(s):  
Arnold Lumsdaine
Keyword(s):  
Topology Optimization ◽  
Loss Factor ◽  
Elastic Beam ◽  
Forced Response ◽  
Optimization Process ◽  
Programming Algorithm ◽  
Optimal Topology ◽  
Modal Strain Energy ◽  
Constrained Damping ◽  
Half Power

The aim of this research is to determine the optimal shape of a constrained viscoelastic damping layer on an elastic beam by means of topology optimization. The optimization objective is to maximize the system loss factor for the first resonance frequency of the base beam. All previous optimal design studies on viscoelastic lamina have been size or shape optimization studies, assuming a certain topology for the damping treatment. In this study, this assumption is relaxed, allowing an optimal topology to emerge. The loss factor is computed using the Modal Strain Energy method in the optimization process. Loss factor results are validated by using the half-power bandwidth method, which requires obtaining the forced response of the structure. The ABAQUS finite element code is used to model the structure with two-dimensional continuum elements. The optimization code uses a Sequential Quadratic Programming algorithm. Results show that significant improvements in damping performance, on the order of 100% to 300%, are obtained by optimizing the constrained damping layer topology. A novel topology for the constraining layer emerges through the optimization process.

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