Bilal Sharqi, Carlos E. S. Cesnik

DOI Number: N/A

Conference number: IFASD-2024-079

Ground vibration testing is typically conducted on an aircraft where the structure is supported using a suspension setup that emulates the free-flying aircraft. When the structure is
very flexible, it is challenging to find a suspension system that can support the structure without influencing its dynamic response. This study investigates the computational and experimental techniques required to conduct such a GVT on a very flexible aircraft and update its finite element model. The two main challenges associated with conducting GVT on a VFA are the measurement of the low frequencies (< 1.0 Hz) related to the test structure and the practical challenge of obtaining a suspension that is soft enough to minimize the interaction between the suspension modes and the elastic modes of the aircraft. For VFA, decoupling of the suspension and airframe modes is typically not feasible. This requires accounting for the suspension in the FEM, which can be achieved by characterizing the suspension upfront as an isolated component and accounting for it in the FEM. This work details the process of performing GVT on a VFA with the suspension model included and removing it once the FEM is successfully updated. This results in a FEM that is dynamically representative of the actual test structure, bypassing the need for an expensive and potentially impractical free-free GVT.

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In Categories: 1. IFASD 2024, 1.Events, Experimental Methods Structural Dynamics and Aeroelasticity
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