A drive minimization technique for component-level response replication in multi-input multi-output random control tests

Multiple-Input Multiple-Output (MIMO) vibration control tests are used to replicate operational vibration environments via shakers excitation. In MIMO random tests, the control target is a reference Spectral Density Matrix (SDM) comprising of Power Spectral Densities (PSDs) and Cross Spectral Densities (CSDs). In particular, the CSDs profiles play a key role in the outcome of the test, as they can affect both the test article response and the voltage required by the shakers (the so called drives). The original contribution of this paper is a MIMO random target definition method that allows to replicate the response of the component tested while minimizing the energy required to conduct the test. The proposed methodology provides the minimum excitation PSDs that allow to replicate the response at a specific location of the device under test. The aim of the proposed methodology is to define a new reference SDM that allows to deal the same damage to the component as a target vibration environment, but with minimal energy. In fact, the minimization of the excitation PSDs also minimizes the drives required to conduct the test, thus preserving the delicate excitation system. The paper outlines the mathematical implementation of the proposed method and validates it through experimental tests. The experiments are conducted on a specially designed specimen by utilizing a three-axial electro-dynamic shaker.