Topic
Constrained-layer damping
About: Constrained-layer damping is a research topic. Over the lifetime, 795 publications have been published within this topic receiving 15758 citations.
Papers published on a yearly basis
Papers
More filters
TL;DR: In this paper, an accurate closed form solution is presented to the problem of determining the damping effectiveness of a damping treatment on a beam consisting of an arbitrary number of alternate viscoelastic and elastic layers.
Abstract: An accurate, closed form solution is presented to the problem of determining the damping effectiveness of a damping treatment on a beam consisting of an arbitrary number of alternate viscoelastic and elastic layers. It was found that the sensitivity of the damping effectiveness to temperature variations may be controlled by using dissimilar viscoelastic layers.
2 citations
26 Mar 1992
TL;DR: In this article, the F-15 upper-outer wing skin has experienced high cycle fatigue cracks caused by separated flow on the upper wing surface and in turn induces large vibratory loads on the lower wing and associated substructure.
Abstract: : The purpose of this investigation was to design, fabricate, and verify candidate add-on damping treatments for the F-15 upper-outer wing skin. The F-15 upper-outer wing skin has experienced high cycle fatigue cracks caused by separated flow on the upper wing surface. The separated flow results during high load factor maneuvers, and in turn induces large vibratory loads on the upper wing skin and associated substructure. The capability of the F-15 to sustain these maneuvers allows the excitation to occur for sufficiently long periods of time to result in damage. Damage accumulates due to the resonant vibration of local skin/stiffener modes. The cracks initiate at the fastener holes adjacent to the integrally machined 'T' stiffeners and tend to propagate parallel to the stiffeners. Two damping treatments resulted from the investigation and were recommended for F-15 fleet retrofit. One was an external constrained-layer treatment and the other was an internal 'stand-off' treatment. Laboratory vibration, corrosion, and thermal aging tests were conducted as part of the development of the add-on damping treatments. Estimates of the life extension factors for the external and internal damping treatments were 5 and 34 respectively. Aircraft vibration, Resonant vibration, Vibration damping, Constrained layer damping, Viscoelastic damping, Fatigue.
2 citations
22 Apr 2002
TL;DR: In this article, the authors developed a higher order assumed modes analysis for a sandwich plate, which is partially treated with constrained layer damping (PCLD) and under clamped-free-clamped free (CFCF) boundary conditions.
Abstract: In this paper, we developed a higher order assumed modes analysis for a sandwich plate. The sandwich plate is partially treated with constrained layer damping (PCLD) and under clamped-free-clampedfree (CFCF) boundary conditions. The base plate uses 2D plate bending and in-plane mode shape functions based on the Kantorovich method. The constraining layer partially covers the span, but covers the chord, and we use free-free 1D rod modes for inplane motions in both x and y directions. We assume the bending displacement compatibility between base and constraining plates. The Golla-Hughes-McTavish (GHM) method was included to account for the frequency dependent complex shear modulus of the viscoelastic core. Natural frequencies, mode shape functions, loss factor and frequency responses of the sandwich plate were calculated and compared to the results of our previous analysis using 1D beam and rod modes to approximate all plate modes in both x and y directions. Fewer modes were needed in current analysis to achieve same accuracy compared to the previous case of using 1D beam and rod modes to represent. The reduction of modal numbers substantially alleviated the computational cost because less corresponding internal dissipation coordinates were needed in the GHM method. Experiments were conducted to validate our predictions and the data agree with our results.
2 citations
TL;DR: In this article, a layerwise finite element (FE) model of plates with constrain layer damping (CLD) treatments is proposed, based on Kerwin's hypothesis, and the dynamic characteristics of CLD system are analyzed by the modal strain energy (MSE) method.
Abstract: The full damping treatments have been widely used in many fields for structural vibration and noise reduction. Compared to the partial damping treatments, the full damping treatments have not significantly enhanced the effect of vibration reductions. It is essential to find the optimal damping treatments in lightweight designs. Moreover, the solution methods should be beneficial to engineering applications. In this work, a layerwise finite element (FE) model of plates with constrain layer damping (CLD) treatments is proposed, based on Kerwin’s hypothesis. The dynamic characteristics of CLD system are analyzed by the modal strain energy (MSE) method. Based on the variable density method and the rational approximation of material properties (RAMP) interpolation scheme, a topology optimization model of the CLD system is built, and the optimal layouts are determined by the proposed modified guide-weight (MGW) method. The results are compared with optimal layouts using other common methods. The layerwise FE model, the topology optimization model and the MGW method are validated by numerical examples. The proposed layerwise FEM-MSE solutions converge to the analytical or semi-analytical solutions more accurately than the NASTRAN/MSE solutions. The optimization results indicate that the added weight of viscoelastic material (VEM) layer decreases by 50 percent, and meanwhile the modal loss factors can just decrease by 5.18 percent compared to plates with VEM full coverage in some cases. The results of this work are beneficial to the vibration and sound radiation suppression of plates with CLD treatments in engineering applications.
2 citations
TL;DR: In this paper , the effect of system vibration damping under different controller parameters, piezoelectric-constrained layer position and excitation signal was studied, and the optimal feedback gain of the controller can effectively balance the control effect and the control cost.
Abstract: This paper deals with the active vibration control of composite cantilever beam. Based on the finite element method and Golla–Hughes–McTavish (GHM) model, the system dynamics equation is established. Models are simplified in physical and modal space because of unobservable and uncontrollable. Based on the particle swarm optimization (PSO) algorithm, the linear quadratic regulator (LQR) feedback gain was optimized. The effect of system vibration damping under different controller parameters, piezoelectric-constrained layer position and excitation signal was studied. The study show that the optimal feedback gain of the controller can effectively balance the control effect and the control cost. The closer the piezoelectric layer and viscoelastic layer are to the fixed end, the better the system control effect and the smaller the control cost. The reduced-order model has a good control effect on different excitation signals.
2 citations