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.

Experimental investigations of lightweight structures with fluidically actuated Compressible Constrained Layer Damping

Abstract: Since strength, stiffness and damping are coupled design variables of fibre reinforced plastics, the lightweight-focused design often leads to a problematic vibration susceptibility of the developed components. This article presents an experimental proof-of-concept of fluidically controlled Compressible Constrained Layer Damping, a novel, semi-active, lightweight-compatible solution for vibration mitigation without explicit actuators. The proposed actuating principle is based on structural cavities generating forces and slight structural deformations when supplied with fluid. The cavities encapsulate compressible, low profile viscoelastic layers operating according to the principle of the Constrained Layer Damping. The intended actuation mechanism controls the thickness of the viscoelastic layers and thus the material properties and the amount of the vibration-induced shear deformation. The described actuating principle is experimentally investigated on a sample composite structure which was excited using an electrodynamic shaker while the vibration response was measured using a laser scanning vibrometer. The obtained results for monofrequent excitation revealed that the compression-driven adjustment allows mobility changes in the range up to 15.8 dB and the mobility can be decreased up to 24.3 dB compared to the untreated base structure due to a shift of the resonance peaks frequency. A second indicator – the adaptive dissipative power – was analysed showing a complex dependency upon the negative actuation pressure and offering a wide adjustment capability.

Dimensionless Analysis of Segmented Constrained Layer Damping Treatments with Modal Strain Energy Method

Abstract: Constrained layer damping treatments promise to be an effective method to control vibration in flexible structures. Cutting both the constraining layer and the viscoelastic layer, which leads to segmentation, increases the damping efficiency. However, this approach is not always effective. A parametric study was carried out using modal strain energy method to explore interaction between segmentation and design parameters, including geometry parameters and material properties. A finite element model capable of handling treatments with extremely thin viscoelastic layer was developed based on interlaminar continuous shear stress theories. Using the developed method, influence of placing cuts and change in design parameters on the shear strain field inside the viscoelastic layer was analyzed, since most design parameters act on the damping efficiency through their influence on the shear strain field. Furthermore, optimal cut arrangements were obtained by adopting a genetic algorithm. Subject to a weight limitation, symmetric and asymmetric configurations were compared. It was shown that symmetric configurations always presented higher damping. Segmentation was found to be suitable for treatments with relatively thin viscoelastic layer. Provided that optimal viscoelastic layer thickness was selected, placing cuts would only be applicable to treatments with low shear strain level inside the viscoelastic layer.

Effect of Thickness of Damping Material on Vibration Control of Structural Vibration in Constrained Layer Damping Treatment

Abstract: The reduction of noise and vibration is a major requirement for performance of any vibratory system. Passive damping technology using viscoelastic materials is classically used to control vibrations. Viscoelastic material among the damping materials is widely used to dissipate the structural vibration energy. Three-layer sandwich beams, made of two elastic outer layers and a viscoelastic layer sandwiched between them, are considered as damping structural elements. This paper presents the effect of thickness of constrained damping material on modal loss factor of vibrating structures. Measurements are performed on sandwich beam structure. In order to understand the effectiveness of the sandwich structures, the dynamics of beam with constrained viscoelastic layers are investigated. Comparisons of the experimental and the Numerical results confirm that the damping levels and the natural frequencies of damped structures are well corroborated.

Constrained‐layer damping analysis for extensional waves in infinite, fluid‐loaded plates

Abstract: This study concerns the mathematical analysis of constrained‐layer damping of extensional waves in plates of infinite extent, with and without fluid loading. Previous work was mostly limited to flexural waves. Some aspects of fluid loading for flexural waves may be understood by means of thin‐plate theory. Therefore, a similar theory was developed for extensional waves. The description and examples presented here are based on three models: The first is an extension of Kerwin’s 1959 model [E. M. Kerwin, J. Acoust. Soc. Am. 31, 952–962 (1959)], the second is a hybrid model in which the base plate is described by exact elasticity theory and the other two layers by Kerwin’s concepts, and the third uses exact elasticity theory for all three layers. It is shown that the extended Kerwin model is useful in the design of constrained‐layer damping for extensional waves as well as for flexural waves.