On Horizontal Beams and Sound Radiation due to a Moving Load

Abstract

Effect of loss factor, rotatory inertia and shear effect on sound radiation by horizontal beams subject to moving loads at subsonic speeds is analysed. Although the contribution of these factors may yield results only a few percentages more accurate and their effect is quite profound when dynamic response analysis is undertaken, it may be an overestimate for slender bodies. The problem is formulated for Timoshenko beam, Rayleigh beam, Shear beam and Bernoulli-Euler beam with complex shear and elastic modulus. Taking Fourier transform of the governing equation the non-dimensional sound radiation is obtained and compared to analyse the contributions of loss factor, rotatory inertia and shear effect on sound radiation. The results show that a Timoshenko beam gives the least sound radiation power when compared with other beam types. The magnitude of sound radiation limited to a maximum of 4-5 % increases as one moves from the Shear beam to the Rayleigh beam to the Bernoulli beam. The effect of structural damping exhibits a relation inversely proportional to the vibration levels. The shift of curves due to damping variation is however found to be proportional to the change in the loss factor

Keywords

• Moving Load, Bernoulli-Euler Beam, Rayleigh Beam, Shear Beam, Timoshenko Beam, Loss Factor, Heavy fluid-loading, Sound radiation