Transverse vibrations of a composite cylindrical tube of circular cross section.

Abstract

The transverse frequencies of vibration of laminated orthotropic cylindrical shells were studied in order to compare experimental results with results predicted by a modified Euler-Bernoulli beam theory. The structures studied had circular cross sections and were made of graphite/epoxy. Stacking sequence for the test structures were [90,╤60₃, 90] and [90,╤45₃, 90]. The structures were tested under clamped-free boundary conditions. Testing was conducted by measuring the Frequency Response Function (FRF) of the structure after exciting it with an impulse from a modal hammer. Response was measured using an accelerometer. Signal processing was done with a digital signal analyzer and FRFs were analyzed using modal analysis software. The experimental data were used to derive a modal model of the test structure. Analytical predictions were made by one dimensionalizing the two dimensional laminated plate theory equations of motion. Treatment of the test structures as a beam was justified by investigating the equations of motion of classical shell theory and making physically reasonable assumptions.