This paper describes that the constitutive factors of structure-borne interior road noise can be decomposed into the following five frequency response functions based on the strict methodology of sub-structures' synthesis. The first is "tire input force" transmitted through wheel hub at rolling state of tire. The second is "suspension's transmissibility", that is, the force transmitted through suspension bushing per unit tire input force. The third is "driving point dynamic stiffness" of body structure at the location of suspension attachment. The fourth is "body vibration transmissibility", defined as the response mode shape of the body panel normalized by the magnitude at the driving point. And the last is driving point. And the last is "vibro-acoustic sensitivity", that is, the sound pressure at the response point generated by unit sound source at the location of sound-radiating body panel. It is shown that the five functions defined above can be acquired experimentally or analytically, and synthesised according to logical formulae for predicting the level of structure-borne interior road noise even in higher frequency range than 200Hz, where the modal analysis is difficult because of so large modal density. Some practicality and usefulness of approximate algebraic transformation with respect to these functions is presented in order to make the criteria of components' characteristics be simplified. (A)
Abstract