Experimentally determining power flow in cylindrical shells using a scanning laser Doppler vibrometer

Abstract

Power flow methods are used to identify energy sources and sinks in objects and to visualize transmission pathways. The most common method uses surface acceleration or velocity measurements and finite difference methods to compute power flow. In flat structures, a scanning laser Doppler vibrometer (SLDV) has been used to increase the measurement resolution. For more complicated surfaces, the general approach has been to use accelerometers at a few key points and measure transmission rather than seeking to get a full visualization of the power flow. This research uses a 3-D-SLDV to take surface velocity measurements for a simply supported cylinder. The 3-D velocity data is used to solve for a quintic B-spline representation of the velocity field. Similar representations for each of the force resultants are generated using an isotropic material model and the Love equations for cylindrical shells. The resultant and velocity fields are used to compute the direction and magnitude of the energy transfer. This method is validated by comparing experimental results to the outputs of an analytical solution and to a finite element model.