Structural qualification testing is critically important to structures in aerospace applications where a unique set of challenges exists. Often testing requirements for large, lightweight aerospace structures cannot be satisfied with conventional static testing for strength qualification; under these circumstances, vibration testing is used. The objective of such vibration testing is to load each component of an aerospace structure with the appropriate peak acceleration. Mode shapes are exploited towards this end, however for a large structure composed of multiple components, modes of predominant motion of each component may be closely spaced in the frequency domain. The difficulty of exciting each to a different peak response level without exceeding the target peak response acceleration on the other is greatly increased. This paper experimentally investigates a near-resonance sine burst testing technique, which is compared with the typical swept sine method. The sinusoidal inputs are designed so that the peak responses of two closely spaced modes are independently controlled to achieve correct test loads. The experimental results provide a guideline for strength qualification testing of aerospace structures.

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