Innovators at NASA’s Armstrong Flight Research Center are developing a collection of algorithms that can accurately determine the structural state of an aircraft. This work is in response to new airframe designs that save weight — and thereby improve fuel efficiency — by removing stiffness in the wings and incorporating lighter materials such as composites.
These lighter and more flexible aircraft tend to be subject to increased aeroelastic phenomena, leading to higher wing loads and gust responses. Divergence, flutter, and other instability can also appear and, if uncontrolled, can lead to catastrophic wing failure. Avoidance of flutter through such methods as notch filtering must be replaced with active control if flutter exists inside the controller bandwidth.
Therefore, Armstrong’s algorithms are being developed as one component that may lead to practical active flutter suppression, as well as load control. Having a modal filtering system that senses the total state of the aircraft’s structure can enable active and timely intervention for control and performance optimization.
The algorithms analyze data quickly, providing real-time operations. They can be used with either photogrammetry or fiber optic sensors, and are insensitive to asymmetric sensor noise and sensor failures. The system collects a large number of data points via distributed sensors to analyze the entire aircraft structure, not just specific areas.
Armstrong has conducted simulations of this technology using computer models with positive results, and flight validation efforts are forthcoming. This technology can be used for aircraft, buildings, and bridges.