The influence of cross-order terms in interface mobilities for structure-borne sound source characterization: Force-order distribution

For the characterization of structure-borne sound sources with multi-point or continuous interfaces, the concept of source descriptor and coupling function can be reformulated by incorporating the interface mobilities. The applicability of this approach, however, depends on the admissibility of neglecting the so-called cross-order terms. Hence, the objective of the present work is to investigate the importance and significance of cross-order terms for the characterization of vibrational sources. Such cross-order terms consist of the previously studied cross-order interface mobilities and the force orders which are addressed herein. The distribution of force orders depends on both the complex data of the contact forces and their location along the interface. From measurements and numerical simulations it is found that the relative magnitudes of the force orders vary up to a factor 10. Only at low frequencies a larger range in magnitude can be observed. Combined with the knowledge of the cross-order interface mobilities, henceforth, a complete assessment of the influence of cross-order terms is possible.