The influence of cross-order terms in interface mobilities for structure-borne sound source characterization: Plate-like structures

Abstract

With the introduction of the concept of interface mobilities, substantial simplifications can be obtained for vibrational source characterization and the description of the associated transmission process involving multi-point or continuous interfaces. The applicability of interface mobilities, however, depends on the admissibility of neglecting the so-called cross-order terms. Under the assumption of a uniform force-order distribution, the cross-order terms reduce to the cross-order interface mobilities. It is demonstrated that the cross-order interface mobilities represent the dependence of point and transfer mobilities on the location relative to boundaries and discontinuities. From theoretical and experimental analyses of circular interfaces located on plate-like structures, it is found that the influence of the cross-order terms features three distinct frequency regions. Provided that the structure can vibrate freely along the interface, the cross-order terms are significant only at intermediate Helmholtz numbers. For engineering practice, however, the omission of the cross-order interface mobilities appears to result in an acceptable estimate throughout the entire frequency range.