Accession Number : ADP004717

Title :   Segmenting and Mechanical Attachment of Constrained Viscoelastic Layer Damping Treatments for Flexural and Extensional Waves,

Corporate Author : BOLT BERANEK AND NEWMAN INC CAMBRIDGE MA

Personal Author(s) : Kerwin,E. M. , Jr. ; Smith,P. W. , Jr

Report Date : NOV 1984

Pagination or Media Count : 24

Abstract : Segmenting (periodic interruption) increases the effectiveness of a constrain-layer damping treatment for flexural waves at frequencies below the peak damping for the continuous system. The interruption of the constraining layer results in induced strains in the viscoelastic layer, giving higher dissipation than for the continuous system. There is an optimum segment length for a given treatment. Discusses the application of segmented constrained layers to the damping of extensional waves. There are significant parallels with the flexural wave case; the optimum segment length for a given damping treatment is essentially the same. As with flexural waves, the results apply below an upper frequency limit. Achievable loss factors for extensional waves are lower than for flexural waves for a given system cross section. Mechanical attachment of the constrained-layer damping treatment is sometimes required. Damping performance is compromised to the extent that the constraining layer lateral deflection is inhibited. Quantitative results on the effect of a point fastener are reported. Results are given for the treatment effective area lost due to a rigid fastener, and for a fastener of finite lateral stiffness. These results can guide the design of fasteners to minimize their effect on performance. (Author)

Descriptors :   *DAMPING, *VISCOELASTICITY, *COMPUTATIONS, INTERRUPTION, DISSIPATION, SEGMENTED, CANTILEVER BEAMS, PLATES

Distribution Statement : APPROVED FOR PUBLIC RELEASE