Diagnostic procedure on brake pad assembly based on Young modulus estimation

Quality control of brake pads is an important issue, being the pad a key component of the braking system. Since the pad - backing plate detachment can alter the mechanical properties of the whole system, the Young Modulus variation could be used for diagnostic purposes, it being a symptom of that impelling damage. The Young Modulus will be estimated from the first bending resonance frequency which will be identified from the Frequency Response Function measured on the pad. Two kind of excitation methods, i.e. impact hammer and magnetic actuation, will be presented and two different measurement sensors, e.g. Laser Doppler Vibrometry and microphone, analysed. A comparison with standard non-contact ultrasonic measurement on a simple isotropic and homogenous aluminium test sample is presented to validate the approach.