An analysis of interlaminar stresses in active constrained layer damping treatments

This paper presents an analysis of the interlaminar stresses in active constrained layer (ACL) damping treatments. The primary objective of this study is to provide in-depth understanding of the delamination of ACL damping treatment and, to establish guidelines to lower the risk of delamination without sacrificing performance. Two major issues are addressed in this investigation. First, the effects of feedback control schemes on interlaminar stresses are analyzed. The proportional (P) and the derivative (D) control laws are selected for comparison. It is found that for the system under consideration, for similar vibration reduction, the derivative control scheme introduces lower interlaminar stresses than proportional control. Also, the derivative control scheme has lower voltage requirements. Second, the ACL treatment is compared with the purely active configuration (without the viscoelastic layer). In addition to the damping performance and control effort requirement (which have been analyzed and compared by researchers in the past), the interlaminar stresses are now included in the comparison. It is shown that the ACL configuration could have significantly lower interlaminar stresses than the purely active configuration, for similar levels of vibration reduction. Hence, in applications where system durability is a concern, the ACL treatment should be preferred over purely active configuration because it has lower interlaminar stress as-well-as lower axial stresses in the piezoelectric cover sheet.