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

This paper presents a study of thickness deformation of the viscoelastic ma terial in constrained layer damping (CLD) treatments. The first goal of the study is to demonstrate the feasibility of using direct measurement to inv estigate thickness deformation in CLD treatments. The experimental setup co nsisted of a constrained lager beam cantilevered to a shaker, an accelerome ter mounted at the cantilevered end, and two laser vibrometers that simulta neously measured the responses of the base beam and the constraining layer, respectively, at the free end. A spectrum analyzer calculated frequency re sponse functions (FRFs) between the accelerometer inputs and the vibrometer outputs. Measured FRFs of the base beam and the constraining layer were co mpared to detect thickness deformation. Experimental results showed that di rect measurements can detect thickness deformation as low as 0.5 percent. T he second goal is to evaluate the accuracy of a mathematical model develope d by Miles and Reinhall [7] that accounts for thickness deformation. FRFs w ere calculated by using the method of distributed transfer functions by Yan g and Tan [13]. Comparison of the numerical results with the experimental m easurements indicated that consideration of thickness deformation can impro ve the accuracy of existing constrained layer damping models M hen the visc oelastic layer is thick.