Quantifying Differences Between MIMO and SISO Testing on the BARC Structure
The comparison of single input single output (SISO) and multiple input multiple output (MIMO) testing is a critical area of research in the field of random vibration testing (RVT). SISO testing is widely used in industry and defense applications but does not realistically reproduce the loading seen in the field environment. Subsequently, SISO testing has the potential to over-test or under-test the structure. MIMO testing allows multiple axes to be controlled simultaneously, creating a more realistic representation of the field environment. Unfortunately, MIMO testing requires more design considerations adding to the complexity of the test setup. It is therefore useful to quantify the similarities and differences between MIMO and SISO testing. This can provide insight to test engineers as they seek to adhere to a test specification while balancing setup complexity. This study analyzes the box assembly with removable component (BARC) structure under MIMO and SISO testing configurations. The BARC has been thoroughly analyzed in the literature, and its well-documented dynamic behavior makes it a viable candidate to investigate the differences between MIMO and SISO testing. Specifically, the distribution of energy, the relative motion between points, and the relative energy between points are studied via calculation of the power spectral density (PSD), transmissibility frequency response function (TFRF), and ratio of PSDs (RPSD). Additionally, the PSDs, TFRFs, and RPSDs are compared to the environment or each other using the Frequency Response Function Similarity Metric (FRFSM).
