4. Investigation of Transmission Simulator-Based Response Reconstruction Accuracy

Response reconstruction tests are typically performed on newly designed structures to ensure they can survive their intended environment. Recent works have shown that using multiple small shakers in a multiple-input multiple-output (MIMO) setup is better at reproducing a random vibration environment everywhere on a structure than a traditional single-axis test. The authors’ prior work sought to reproduce the environment everywhere on a part while controlling only to a subset of accelerometers on a component called the transmission simulator (TS) and found that the results were quite sensitive to how well the impedance matched between the test and the environment of interest. This paper studies this further, varying the degree to which the impedance matches between test and the in-service environment, to see the effect that this has on the fidelity of the response reconstruction at both the controlled and uncontrolled locations. To obtain additional insights, the comparison is performed utilizing results from both simulated and experimental MIMO tests. The results show in a systematic way how the response reconstruction becomes more accurate at the uncontrolled locations as the impedance of the TS improves. Furthermore, the results show that one can simulate the MIMO test to predict much of what is seen in real experiments, providing a rudimentary metric for quantifying the impedance match of TS prior to performing the MIMO tests.