Damping Characteristics of Laminated Semi-Cylindrical Shells: Technical Note

Abstract

The natural frequencies and damping co-efficient were obtained in a half-cylindrical shell made up of epoxy resin reinforced with glass fibre. The impact load is given by an impact hammer and the effect of impact load is sensed using an accelerometer, which is fixed at the edge of the cylinder. Results are manipulated directly by the system through the accelerometer. The laminated shells were tested with various boundary conditions such as free-free, fixed–fixed and simply supported end. The same tests were conducted on the shells with longitudinal stiffeners. The damping characteristics were compared. From the results it was found that shells without stiffener have a damping co-efficient of 0.177 and the shells with stiffener have a damping co-efficient of 0.311 in free-free end condition. Here it is understood that the shells with stiffener showed 43% improvement in damping co-efficient also. It was also observed that with the addition of rubber particles to the reinforcing polymer, the shells with stiffeners may lead to significant increase in damping co-efficient