Vibroacoustic behavior with total or partial layer of constrained viscoelastic

The actual efficiency of constrained viscoelastics layers is sometimes misunderstood. To study in depth this configuration, a theoretical approach has been developed by generalizing Ungar’s formulation [E. E. Ungar, J. Acoust. Soc. Am. 34, 1082–1089 (1962)]. The shear effect, ‘‘in‐plane’’ motion, and flexion are taken in account into the viscoelastic layer while only flexion is considered for the metallic layer. By expressing ‘‘in‐plane’’ and shear displacements in terms of transverse displacements, a linear system is obtained. Radiation impedances are calculated via Nelisse’s model [H. Nelisse et al., J. Sound Vib. 198(4), 485–506 (1996)]. The theoretical results have been systematically validated experimentally with a dedicated setup. Basic configurations of interest are: basic plate, basic plate and constrained viscoelastic layer with total or partial covering under or not under the excitation forces. A case of nonmetallic (fiber resin) material is also studied, leading to very interesting results. Fin...