The Radiation of Sound from Mass-Loaded and Stiffened Beams

This study examines the sound radiation efficiency of uniform, mass-loaded, and stiffened beams. The radiation efficiency of vibrating beams is determined using a finite element vibration model of the beam and a numerical approach to determine the radiated sound field. The radiation efficiency of mass-loaded and stiffened beams deviates from that of the uniform beam for frequencies near and below coincidence. The radiation efficiency of the nonuniform beams depends on the change in natural frequency and the distortion of the mode shape of the vibrating beam. Near coincidence, the radiation efficiency of nonuniform beams approaches that of the uniform beam. Above coincidence, all beams exhibit a radiation efficiency of unity.