Modal testing and model correlation of a lumped parameter vibroacoustical system

Vibroacoustical modal analysis is applied to a lumped parameter coupled hydraulic-mechanical system. Hydraulic excitation is realized by a chirp flow rate signal through a servovalve. Mechanical force excitation is applied by an impact hammer. In each case, five pressures and two accelerations are measured. For further processing, the signals are weighted by the square roots of the mean hydraulic capacity and the mean stiffness, respectively. A lumped parameter theoretical model is set up and frequency response functions are compared to measurements. An eigenvalue analysis results in six mode shapes, which are compared to those extracted from servovalve and impact hammer excitation. Recently presented model correlation criteria are applied to assess the autocorrelation of measured modes and their agreement with theoretical ones.