A 9 meter TX-100 wind turbine blade, developed under a Sandia National Laboratories R&D program, was recently fatigue tested to blade failure at the National Renewable Energy Laboratories, National Wind Technology Center. The fatigue test provided an opportunity to exercise a number of structural health monitoring (SHM) techniques and nondestructive testing (NDT) systems. The SHM systems were provided by teams from NASA Kennedy Space Center, Purdue University and Virginia Tech (VT). The NASA and VT impedance-based SHM systems used separate but similar arrays of Smart Material macro-fiber composite actuators and sensors. Their actuator activation techniques were different. The Purdue SHM setup consisted of several arrays of PCB accelerometers and exercised a variety of passive and active SHM techniques, including virtual and restoring force methods. A commercial off-the-shelf Physical Acoustics Corporation acoustic emission (AE) NDT system gathered blade AE data throughout the test. At a fatigue cycle rate around 1.2 Hertz, and after more than 4,000,000 fatigue cycles, the blade was diagnostically and visibly failing at the blade spar cap termination point at 4.5 meters. For safety reasons, the test was stopped just before the blade completely failed. This paper provides an overview of the SHM and NDT system setups, and some test results.

The modal response of a liquid-filled tank to external acoustic excitation can be used to infer with high resolution the mass of contained liquid, the mass flow rate of liquids into and out of the tank, and changes in tank pressure. Both contained liquid mass and internal ullage pressure affect the modal response of the tank walls through fluid mass-loading of the tank walls and pressureinduced wall stiffening, respectively. Modal Propellant Gauging refers to the technology that exploits these shifts in modal frequencies to infer the mass of propellant in a tank. MPG is a noninvasive gauging technology that has demonstrated gauging resolutions of 1% for settled propellants and 2-3% for unsettled, sloshing propellants. Extensive parabolic flight testing of the MPG system on model tanks has been conducted to validate the technology in reduced gravity. MPG testing on a qualification tank for the Orion Program's European Service Module has also been conducted and is reported here. Finite element modeling of the Orion ESM ″upper" tank is discussed and compared with measurement data. Three computational approaches to mass determination, Peak Tracking, Point Sensor, and Spectral Density methods, are described here. Use cases are defined and analyzed in the context of the Orion ESM Qualification tank data, and an implementation scheme for continuous mass gauging on the Orion ESM is discussed.

No abstract

No abstract

The use of glass bubbles as an efficient and practical thermal insulation system has been previously demonstrated in cryogenic storage tanks. One such example is a spherical, vacuum-jacketed liquid hydrogen vessel of 218,000 liter capacity where the boiloff rate has been reduced by approximately 50 percent. Further applications may include non-stationary tanks such as mobile tankers and tanks with extreme duty cycles or exposed to significant vibration environments. Space rocket launch events and mobile tanker life cycles represent two harsh cases of mechanical vibration exposure. A number of bulk fill insulation materials including glass bubbles, perlite powders, and aerogel granules were tested for vibration effects and mechanical behavior using a custom design holding fixture subjected to random vibration on an Electrodynamic Shaker. The settling effects for mixtures of insulation materials were also investigated. The vibration test results and granular particle analysis are presented with considerations and implications for future cryogenic tank applications.