A Rectangular Plate as a Proposed Modal Test Structure

Studies show that a rectangular plate can be used for several purposes, such as comparing various modal systems and modal extraction algorithms, comparing test techniques, and training new personnel in these tasks. Efforts to develop a simple structure for comparison of modal systems led to the plate. A structure was desired which would be easy to analyze, have well defined properties, be easy to fabricate, have both widely spaced and closely spaced modes, and have a moderate amount of damping. The plate, which is roughly 53 cm long by 32 cm wide by 2 cm thick, is constructed of polymethyl methacrylate, a material that provides internal damping of 2% to 3% of critical.