Broadband Vibration Test Condition Design for Aerospace Structure Based on Response Equivalence

Proper broadband vibration test conditions are essential for reproducing the dynamic environment of an aerospace structure. Existing design methods, such as the maximum envelope method (MEM) and the force-limited method (FLM), are either model-free or based on deterministic models and thus cannot adequately describe broadband dynamic characteristics. Therefore, they may lead to overtesting and/or undertesting. To address this issue, a novel broadband vibration test condition design approach is proposed based on hybrid finite element–statistical energy analysis (FE-SEA) theory to achieve target response equivalence between the dynamic environment in vibration test (DEIVT) and the dynamic environment in operation (DEIO). First, the required input power under DEIVT is formulated with target FE and/or SEA subsystem responses under DEIO. Second, a new method is presented to solve input power solely through FE subsystem responses, which circumvents the common unavailability of SEA subsystem responses under DEIO. Lastly, a transformation method is offered to obtain the broadband vibration test condition from input power. Studies on a complex built-up structure and a propellant tank in the attitude control engine show that the proposed method generates a more appropriate broadband vibration test condition than MEM and FLM in terms of target response equivalence between DEIVT and DEIO, and thereby provides an effective design approach for mitigating overtesting and undertesting.