Responses of Structures to SDoF vs. MDoF Vibration Testing

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The vibration excitation mechanisms for structures in service are typically multi-directional. However, during product testing conducted in a lab setting the standard practice is to replicate these environments with three orthogonal single axis vibration tests. Recent advances in technology have made it possible to perform multi-axis simulations in the laboratory. Simultaneous multi-axis excitation can result in different stress states, rates of damage accumulation, and peak accelerations and strains than those resulting from sequential single axis testing. Accordingly, a series of experiments were run on a plate structure to investigate and quantify these differences. The experiments included single and multiple axis tests with different excitation amplitudes. The single axis tests were performed on both uniaxial and multiaxial shaker systems. The control levels, response energy, modal behavior, and peak accelerations were compared for each test condition. The data illustrates the differences between the structural response for single and multi-axis tests and enables an objective comparison between testing conducted on single and multiple axis shaker systems.