Building sophisticated systems for our customers to help them innovate beyond the problems of today has been a Sensuron mission since the company was founded seven years ago. The need to establish a new and robust technology that could continuously monitor durability over time was a priority for our first customer and partner, NASA. Since then, we have worked with NASA to develop the next generation of fiber optic sensing technology. We continue to enhance our systems and now provide unparalleled sensing and measurement to applications across industries. Our work with NASA has evolved to include flight-testing and validation, as well as wing load testing. Here’s an overview of how Sensuron’s technology provides next generation sensing abilities to the National Aeronautics and Space Administration.
NASA began using fiber optic shape and strain sensing systems to test flight validation in 2008. By applying over 3000 FBGs to the wings of the Ikhana aircraft, NASA Armstrong was able to monitor stress and observe the shape of the wings in real-time throughout each mission. This served as the first step to achieving control of the shape of subsonic fixed wing aircrafts. The capability demonstrated by the sensing system also provided a practical approach to accomplish structural health and loads monitoring. The NASA Dryden designed FBG-OFDR system, a precursor to Sensuron’s RTS125, was developed, environmentally qualified, and integrated in the avionics bay of the Ikhana vehicle.
Prior to flight-testing, ground validation testing was conducted using a high resolution/high speed optical measurement system developed by Sensuron. The optical system utilized bar-coded targets placed on the left wing and center fuselage at 10 measurement locations. The maximum loads applied to the wings were limited to 200 lb. This produced displacements at the wing tips of approximately 3 in.
After the success flight validation testing using FBG sensing on Ikhana, NASA began real-time strain sensing on a full-composite Unmanned Aircraft Vehicle (UAV). AeroVironment’s Global Observer aircraft is capable of stratospheric flight up to 65,000 ft over 7 days without landing or refueling. Eight 40-ft long fibers written with over 8,000 FBG sensors were installed along the forward and aft wing portions of the left wing, as well as a single fiber along the fuselage to measure torsion. Strain measurements were taken in real-time at 20 samples per second per sensor providing monitoring of the fuselage and trailing edges of the wings. NASA conducted further tests and successfully recorded strain information that contributed to giving the Global Observer a successful completion of the flight test.
Wing Load Testing
The purpose of wing load testing is to monitor the strain of wing panels under load and to monitor the wing shape of the panels using the NASA-patented wing shape algorithm. Eighteen fibers, each consisting of up-to 1000 FBG sensors, were bonded to the forward and aft portion of both wings as well as to the fuselage. The wing-load test composed of subjecting each wing panel to 100% of design load in both positive load and negative load at various angles of attack. Structural response of the wings was successfully quantified in the FBG-OFDR, photogrammetry, and traditional strain-gauge systems at various locations. Post-data analysis verified that the FOS measurement is in agreement with traditional strain gages.
NASA continues to test the boundaries of aeronautics engineering and Sensuron’s fiber optic sensing systems have been imperative to testing and monitoring of the latest aircraft of innovation. Sensuron’s technology continues to allow NASA’s engineers to test, monitor and control in-flight and design applications, providing unprecedented levels of data density and next generation FOS sensing technology.