The optimization of constrained layer damping applications

Abstract

It is well known that the attachment of a stiff elastic (constraining) layer to a beam by using a viscoelastic damping adhesive can be a highly weight efficient means of reducing the beam's resonant response if this damping treatment is carefully designed. Though the prediction of the damping effectiveness of constrained layer damping treatments has been well understood for over twenty years, their optimum design is often obtained by trial and error. To avoid this, an efficient method is presented for optimizing the adhesive layer's thickness. This is usually the most difficult parameter to optimize and existing design guidelines are not always accurate. It is shown that if the ratio of the “effective” shear stiffness of the adhesive layer to the “effective” extensional stiffness of the metal layers is greater than a factor that depends only on the adhesive's loss tangent, the damping effectiveness will increase monotonically with increasing adhesive layer thickness. If the ratio is less than this factor there will be some optimum value of adhesive layer thickness. The value of this thickness is obtained by a simple numerical procedure.