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.

Damping Characteristics of Beams with Enhanced Self-Sensing Active Constrained Layer Treatments Under Various Boundary Conditions

Abstract: In this paper, an energy-based approach is developed to investigate damping characteristics of beams with enhanced self-sensing active constrained layer (ESACL) damping treatments. Analytical formulations for the active, passive, and total hybrid modal loss factors of the cantilever and simply-supported beams partially covered with the ESACL are derived. The analytical formulations are validated with the results in the literature and experimental data for the cantilever beam. Beams with other boundary conditions can also be solved and discussed using the presented approach. The results show that the edge elements in the ESACL can significantly improve the system damping performance as compared to the active constrained layer damping treatment. The effects of key parameters, such as control gain, edge element stiffness, location, and coverage of the ESACL patch on the system loss factors, have been investigated. It has also been shown that the boundary conditions play an important role on the damping characteristics of the beam structure with the ESACL treatment. With careful analysis on the location and coverage of the partially covered ESACL treatment, effective vibration control for beams under various boundary conditions for specific modes of interest would be achieved.

Vibration Analyses of Cylindrical Hybrid Panel with Viscoelastic Layer Based on Layerwise Finite Elements

Abstract: Based on full layerwise displacement shell theory, the vibration and damping characteristics of cylindrical sandwiched panels with viscoelastic layers are investigated. The transverse shear deformation and the normal strain of the cylindrical hybrid panels are fully taken into account for the structural damping modeling. The layerwise finite element model is formulated by using Hamilton’s virtual work principle and the cylindrical curvature of hybrid panels is exactly modeled. Modal loss factor and frequency response functions are analyzed for various structural parameters of cylindrical sandwich panels. Present results show that the full layerwise finite element method can accurately predict the vibration and damping characteristics of the cylindrical hybrid panels with surface damping treatments and constrained layer damping.

Dynamics analysis of constrained layer damping treated covers for hard disk drives

Abstract: A finite element model is developed to study the dynamics properties, vibration, shock and acoustics performance of constrained layer damping treated covers for hard disk drives (HDD). The ever-increasing storage density of HDD requires smaller vibration level of HDD components, especially the storage disks inside. In the mean time, tighter vibration, shock and acoustics specifications are required by customers. In practice, it is found that the vibration of the storage disks and the shock/vibration and acoustics performance of HDD are closely related to the properties of the HDD covers. The existence of viscoelastic materials (VEM) inside the HDD covers makes them hard to analyze and the complex modulus provided by VEM manufactures can only be utilized in frequency domain. In this paper, the VEM properties are fitted with GHM (Golla, Hughes and McTavish) parameters so that a complex eigenvalue analysis can be performed to extract modal frequencies and damping of the cover. Parametric study is conducted to understand how some essential design parameters affect the dynamics properties of the cover. Vibration/shock and acoustics responses of the cover are also simulated to provide insights for HDD cover design.

Performance of vertically reinforced 1-3 piezo composites for active damping of smart sandwich beams

Abstract: This paper deals with the performance of vertically reinforced 1-3 piezoelectric composite material as a constraining layer for active constrained layer damping of sandwich beams. A finite element model, considering both in-plane and out-of-plane actuation of the constraining layer of the active constrained layer damping, has been developed for analyzing the active damping of sandwich beams integrated with the patches of such active constrained layer damping treatment. The analysis revealed that vertically reinforced 1-3 piezo composites, which are popularly used as sensor materials, can be used as distributed actuators of smart sandwich beam.

Optimization Of Passively Damped Composite Structures

Abstract: Both in-plane and out-of-plane damping in fiber-reinforced composites have been increased from the undamped structures' nominal 1% loss factor to more than 10% using structurally enhanced stress coupling to co-cured viscoelastic layers. Reductions in strength and stiffness can be minimized. A computer model allows dynamically stiff composite components to be optimized for stillness, loss factor, damping frequency, and strength. A design with an axial loss factor of 1.49% was optimized for strength and stiffness with constraints on loss factor. The axial loss factor increased to 5.11% with strength increasing 400% and stiffness increasing 1000%. Initial experiments have shown that this modelling method predicted resonant frequencies within 3% and loss factors within 15%. Typical constrained layer damping would not have increased the in-plane axial loss factor to any significant degree.