As aircraft become more flexible in an effort to improve efficiency to reduce fuel consumption and operating costs and improve endurance, structural nonlinearities become more apparent. As a consequence, testing practices that are well established and mature for traditional, relatively rigid aircraft need to be re-examined. Modal characterization of very flexible aircraft through ground vibration testing is challenging due to geometric nonlinearities and very low natural vibration frequencies (typically below 1 Hz). Geometric nonlinearities make the aircraft modal parameters a function of the deformed shape and, therefore, of the applied loads. The low natural vibration frequencies make the support system influence even more difficult to eliminate. This study investigates the computational and experimental techniques required to conduct a ground vibration test on a very flexible aircraft. The finite element model of the aircraft is then updated using a model updating methodology that accounts for large deflections and flexibility of the test structure. A validation of the ground vibration testing and finite element model updating methodologies is then performed on the very flexible aircraft. Results indicate that the updated finite element model of the aircraft is able to accurately capture the free-flight response of the as-built, very flexible aircraft structure.
Ground Vibration Testing of Very Flexible Aircraft
Journal of Aircraft ; 1-20
2025-07-01
Conference paper , Article (Journal)
Electronic Resource
English
Ground Vibration Testing on Very Flexible Aircraft
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