Gear rattle, clunk, and other such noises, commonly referred to as impulsive or unusual noise, are often classified as unique problems without common origins. This paper examines the underlying structure that promotes them and traces physical system behaviors that predispose them to such noises. Though the audible noise itself is not modeled directly, a good deal of the disposable energy that sustains it can be inferred from the impulsive dynamics that underlies the whole process. Further effort quantifies the energies involved and appraises the distinctiveness of the perceived noise. Whether one hears gear rattle or clunk depends on the initiating site within the system and the impulsivity index of the prevailing dynamics.
Observable indicators suggest that periodic noise is supported by periodic dynamics and, similarly, impulsive noise, by impulsive dynamics and that the latter is non-deterministic, discontinuous and even chaotic. The uniqueness of impulsive dynamics stems from the fact that the orderly energy-to-power exchanges of periodic dynamics gives way to direct energy-to-energy exchanges, with attendant rise in impulsivity. It becomes evident that addressing the impulsive noise problem will require reduction in the impulsivity index and, hence, this paper shows how to construct system models with ability to express impulsive dynamics and suggests use for impulsivity indices as a means of testing suppression remedy effectiveness in the same manner as guinea pigs are used to test potential vaccines. The add-on impulsive dynamics algorithm does not inhibit system periodic expression but manifests itself, only in the concurrent presence of lash and torque reversal conditions. Concepts outlined above are demonstrated on a popular rear-wheel-drive truck to demonstrate how to quantify severity of a clunk response.