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.

Low profile, multi-axis, highly passively damped, vibration isolation mount

Abstract: The invention disclosed is a low-profile, multi-axis, highly passively damped, vibration isolation mount which when used in multiplicity provides a complete vibration load isolation mounting system. The device provides in unique fashion a very low profile interface in combination with independently determinable compliance in all directions of vibration loading. Substantial passive damping is afforded without sacrifice to strength and linearity of behavior through adaptation of a shear wall type constrained layer damping. The result is a highly passively damped vibration isolation device that provides a very low profile interface, wide ranging longitudinal and lateral compliance management, in a durable, reliable, lightweight, and compact form.

Effect of Delamination on Active Constrained Layer Damping of Smart Laminated Composite Beams

Abstract: An ove lw ork demonstrates the effect of delamination in smart laminated composite beams on the performance of active constrained layer damping (ACLD) treatment. A finite element model has been derived to formulate the dynamics of the composite beams integrated with a patch of ACLD treatment and a patch of piezoelectric film acting as a distributed sensor with and without the presence of delamination at different locations. Frequency response functions of the beams have been examined to observe the effect of delamination on the performance of ACLD treatment. It has been observed that the ACLD treatment improves the active damping characteristics of the beams, even in the presence of delamination, and that the responses of the beams are sensitive to the variation of the location of delamination. The responses due to active constrained layer damping presented may provide a useful guide to detect the presence of delamination in smart composite beams by the use of the existing numerical techniques.

Effectiveness of Active Constrained Layer Damping Treatments in Attenuating Resonant Oscillations

Abstract: This paper highlights the importance of considering the piezoelectric constraining layer voltage limits when evaluating the effectiveness of an active constrained layer damping treatment in attenuating resonant vibration. It is seen that when position feedback is used, intermediate viscoelastic layer stiffness values are always optimal, and maximum control gains and possible vibration attenuation progressively decrease with increasing excitation levels. On the other hand, with velocity feedback, the optimal viscoelastic layer stiffness is dependent on the excitation level. For low excitation force amplitudes, stiff viscoelastic layers are most effective and very large velocity feedback gains are permissible (producing substantial vibration attenuation without exceeding piezoelectric layer voltage limits). However, for higher excitation force levels, stiff viscoelastic layers result in excess voltages even at very small velocity feedback gains, and are unable to provide any vibration attenuation. In such a case, intermediate viscoelastic layer stiffness values are preferable, and maximum velocity feedback gains and possible vibration attenuation progressively decrease with increasing excitation level, as in the case of position feedback.

Thickness deformation of constrained layer damping : An experimental and theoretical evaluation

Abstract: This paper presents a study of thickness deformation of the viscoelastic material in constrained layer damping (CLD) treatments. The first goal of the study is to demonstrate the feasibility of using direct measurement to investigate thickness deformation in CLD treatments. The experimental setup consisted of a constrained layer beam cantilevered to a shaker, an accelerometer mounted at the cantilevered end, and two laser vibrometers that simultaneously measured the responses of the base beam and the constraining layer, respectively, at the free end. A spectrum analyzer calculated frequency response functions (FRFs) between the accelerometer inputs and the vibrometer outputs. Measured FRFs of the base beam and the constraining layer were compared to detect thickness deformation. Experimental results showed that direct measurements can detect thickness deformation as low as 0.5 percent. The second goal is to evaluate the accuracy of a mathematical model developed by Miles and Reinhall [7] that accounts for thickness deformation. FRFs were calculated by using the method of distributed transfer functions by Yang and Tan [13]. Comparison of the numerical results with the experimental measurements indicated that consideration of thickness deformation can improve the accuracy of existing constrained layer damping models when the viscoelastic layer is thick.