Camille GREGOIRE : Contact Noise: identifying the exciter field by inverse method

Abstract :

The vibro-acoustic behaviour of structures excited by sliding contacts remains a challenging issue to understand, estimate and possibly control the level of the radiated noise, in many situations as squeal, cracking and roughness noises. A great challenge in contact noises is the understanding of the normal and tangential forces at the contact interface between frictional structures.
This aim of this thesis work is to get a better understanding of the normal forces involved in dry friction between rough surfaces under low normal load. First, we focused on the contact scale to develop a device to measure on the local forces at the contact interface. An instrumented slider, that can measure those forces directly at the contact interface between the slider and a rough surface, has been designed, realized and experimentally validated.
Using this device, friction tests were performed to understand the spatial distribution of dynamical interactions between the slider and the surface across a wide frequency range, up to 10kHz.
Then the aim at the structure’s scale is to develop an inverse method permitting to localize spatially and temporally a moving frictional excitation from the signals of accelerometers placed far from the contact. This method could be validated using the signal of the above-mentioned instrumented slider as a reference and comparing it to the inverse method’s results.