Dynamic behaviour characterization of a brake disc by means of electronic speckle pattern interferometry measurements

A complete experimental approach is here carried out to obtain the dynamic characterization of an automotive brake disc fixed on its grounded knuckle. The operative deflection shapes (ODS) were measured under harmonic excitation in the 1-23 kHz frequency range. Electronic Speckle Pattern Interferometry (ESPI) [1, 2] technology was exploited to measure high spatially defined full field displacement maps at each frequency by means of optical non-contact techniques. The harmonic excitation source was an electrodynamic shaker. The displacement maps acquired depict the dynamic behavior of the brake disc with high accuracy in the whole range, from the global bending modes at low frequency to the arising of small lobes at high frequency, with particular attention paid to the transition over resonance frequencies. Results are reported and discussed in detail.