Experimental direct spatial damping identification by the Stabilised Layers Method

A new method is developed for direct damping matrix identification using experimental receptance-matrix data together with physical connectivity constraints based on what are described as layers. A number of spectral lines are considered in symmetric frequency bands around the damped peaks of the receptances and the identification procedure is shown to be ill-conditioned (singular) when one of the spectral lines coincides with an undamped natural frequency. A test is developed that makes use of a stabilisation diagram to ensure not only that a solution exists, but also that it is stable when the number and frequency range of the spectral lines is changed. An experimental parametric three degrees of freedom lumped mass system connected by springs and air dampers is considered and the matrix of non-proportional viscous damping terms is identified under different damper configurations and levels.