Physical parameters of a welded t-joint that impact structural acoustics

Abstract

The influence of welded joints on the accuracy of analytical structural acoustic models is investigated. A beam with a T-shaped rib attached to it is studied. Welding a t-joint causes geometry variation, static stress, and material variations that are not currently included in computational models of the structural acoustics of a t-joint. Two techniques of processing the experimental data are used to show that the geometry and the static stresses caused by welding can have a significant impact on waves propagating past the joint and the resulting radiated sound power. Likewise experimental results show that the material variation caused by the welding of the joint has minimal impact on the wave propagation and sound radiation from the beam. The processing techniques are a phase-speed tracking filter and wave-number filtering. The phase-speed tracking filter shows an increase in the phase speed of propagating waves near the joint. There is also a reduction in the group delay of wave packets propagating past the joint and a change in the reflection coefficient of structural waves incident on the joint. The wave-number filtering is used to quantify the amount of far-field sound radiation from the area of the t-joint on the beam. Finally an analytic model that describes a rib as imparting a force and moment on a beam in reaction to the incident structural waves is modified to include the influence of the weld fillet geometry and static stress induced by welding. [Work supported by ONR, Dr P.B. Abraham Scientific Officer.]