Transmission Simulator Based MIMO Response Reconstruction

Abstract

Current industry standard environmental verification testing methods typically employ a single shaker to subject a component to a desired environment in one axis at a time, which has been shown to result in over- or under-testing on the various axes and hence a poor representation of the desired environment. This paper explores a new verification testing methodology based on a combination of the Transmission Simulator Substructuring Method (TSM) with the Impedance Matched Multi Axis Testing (IMMAT) method. The new method seeks to verify the survival of a subcomponent in a given environment using only environmental measurements on the structure to which the subcomponent is attached. A Transmission Simulator (TS) is used to maintain the same connection geometry between the subcomponent and the rest of the vehicle such that the dynamics of the subcomponent are better matched. Impedance Matched Multi Axis Testing is then used to recreate the full environment on the Transmission Simulator in all axes at once. If the impedance between the Transmission Simulator and the subcomponent is sufficiently similar and if the control is successful in reproducing the response on the Transmission Simulator, the motion of the subcomponent of interest should match its motion in the desired environment and produce an accurate reconstruction test. To evaluate this new methodology, simulations were performed using roving hammer data both to optimize the test design and to evaluate the best possible performance. Multi-input-multi-output (MIMO) tests were then performed using a commercial control system to assess the accuracy of the method. These cases showed that the proposed approach was able to reconstruct the desired environment with moderate accuracy, but the response away from the Transmission Simulator was found to be very sensitive to the design of the Transmission Simulator.