Coupling loss factor estimation for plates joined along a line: Analysis and experiment.

Abstract

Coupling loss factors for two plates joined at a line (a 90‐deg bend), but otherwise free to respond in lateral vibration, have been studied both analytically and experimentally. Two cases have been studied: one with no added damping and one in which one of the plates has a small amount of damping provided by a constrained layer treatment. Statistical energy analysis (using VA ONE) and the finite element method (using NASTRAN) have been used to predict the coupling loss factors. The finite element predictions are based on the averaged responses for a range of boundary conditions on the plates, essentially a “pseudo‐statistical” approach. Experimentally, one of the plates was excited while the kinetic energy of the two plates was assessed with a scanning laser vibrometer (scanning a dozen or more points) and four accelerometers on each plate. Both impulse and persistent excitations were used. The coupling loss factors were assessed by balancing the power input with the energies of the plates, also using the estimated modal densities. The estimations from the analytical and experimental approaches compare as well as may be expected for the lightly damped plates case, but very well for the case of one plate having a damping treatment.