Effect of Mode Shape Switching on the Loss Factor of Sandwich Cylinders

Abstract

Damping characteristics of three-layered sandwich cylindrical shells with the focus on mode switching phenomenon are investigated in the present study. All layers of the sandwich cylinder are formulated based on the first-order shear deformation theory. Considering the von Karman strain displacement relations, the nonlinear equations of motion are derived through Hamilton’s principle. By separating the displacement components into previbration and vibration states and substituting in the obtained nonlinear equations of motion, the previbration equilibrium equations and vibration equations of motion are obtained. The acquired equations are solved by applying the generalized differential quadrature method. The method is validated by comparing the obtained results with those available in the literature. The effects of temperature, length-to-radius ratio, and radius-to-thickness ratio on the fundamental loss factor of sandwich cylindrical shells are examined at different boundary conditions. Also, variation of the fundamental loss factor of the sandwich shell with variation in the thickness of the constraining and core layers is investigated. The results show superior effect of the mode shape switching phenomenon on the fundamental mode loss factor variation. Temperature rise results in significant reduction of loss factor values. Depending on boundary conditions, the length ratios at which mode shape switching occurs may remain constant or change with increasing the temperature. Some new results are also reported to serve as benchmarks for future studies of such structures.