Test & Measurement

Directed Design of Experiments for Validating Probability of Detection Capability of a Testing System

NASA’s Langley Research Center has developed new software that enables users of critical inspection systems to validate the capability of the inspection system. Traditionally, inspection systems are validated using various methodologies to determine probability of detection (POD). One widely accepted metric of an adequate inspection system is that there is 95% confidence that the POD is greater than 90% (90/95 POD). Directed Design of Experiments for Probability of Detection (DOEPOD) is a user-friendly software package that enables detailed analysis of 90/95 POD or at any specified confidence level. Although it was designed to validate the capability of inspection systems to find fracture- critical flaws in materials, DOEPOD can be applied to systems to locate any type of flaw as well as to validate the detection capability of personnel. DOEPOD can also be employed as the core of an NDE (nondestructive evaluation) system, and provide accurate on-demand validation of the inspection system.

Posted in: Briefs, Test & Measurement, Failure modes and effects analysis, Measurements, Computer software / hardware, Computer software and hardware, Computer software / hardware, Computer software and hardware, Inspections

Method and Apparatus for Measuring Surface Air Pressure

This technology enhances the predictive capabilities of weather forecasting models.

NASA’s Langley Research Center has developed a novel method for long-range atmospheric pressure sensing. Based on known properties involving oxygen density, the technology is able to measure small pressure changes over a wide area. NASA developed the technology to address known gaps in the area of weather forecasting as a result of the inability to accurately detect atmospheric pressure above the ocean. Oxygen band reading can be performed remotely, most likely from a satellite-based system. The technology is particularly applicable in the area of storm forecasting.

Posted in: Briefs, Test & Measurement, Measurements, Radar, Radar, Weather and climate, Oxygen

HEIST Ironbird to Test Cutting-Edge Hybrid Electric Propulsion Technologies

Testbed will study the system complexities of powering an aircraft with two different power sources.

A key goal of NASA’s aeronautics research is to help the aircraft industry transition to low-carbon propulsion. Many potential power architectures for electric propulsion have been proposed, and design considerations for turbo-electric distributed propulsion have been studied. However, few mid- to full-scale testbeds have been built to validate these different architectures.

Posted in: Briefs, Test & Measurement, Electric hybrid power, Electric motors, Turbojet engines, Turboprop engines

Saturn Net Flux Radiometer (SNFR)

A Saturn Net Flux Radiometer (SNFR) is being developed as part of a payload for a future NASA-led Saturn Probe Mission. The current design has two spectral channels i.e., a solar channel (0.4-to-5 μm) and a thermal channel (4-to-50 μm). The SNFR is capable of viewing five distinct viewing angles during the descent. Non-imaging Winston cones with window and filter combinations define the spectral channels, each with a 5° field-of-view. Un - cooled thermopile detectors are used in each spectral channel and are read out using a custom-designed Application Specific Integrated Circuit (ASIC). The SNFR measures the radiative energy anisotropies with altitude. In the solar channel, the downward flux will determine the solar energy deposition profile and the upward flux will yield information about cloud particle absorption and scattering. In the thermal channel, the net flux will define sources and sinks of planetary radiation. In conjunction with calculated gas and particulate opacities, these observations will determine the atmosphere’s radiative balance.

Posted in: Briefs, Test & Measurement, Measurements, Radar, Radar, Solar energy, Radiation, Thermal testing, Entry, descent, and landing

Applying the Dynamic Inertia Measurement Method to Full-Scale Aerospace Vehicles

Researchers have begun testing on large articles in conjunction with ground vibration tests.

Researchers at NASA’s Armstrong Flight Research Center have been interested in using the Dynamic Inertia Measurement (DIM) method on full-scale aerospace test vehicles, given its advantages over traditional methods for determining the mass properties of such vehicles. Developed at the University of Cincinnati, the DIM method uses a ground vibration test setup to determine mass properties using data from frequency-response functions. The method has been successfully tested on a number of small-scale test articles — including automobile brake rotors, steel blocks, and custom fixtures — but until now, has had limited success being tested in larger applications. Armstrong’s recent efforts, in conjunction with ground vibration tests, represent a step forward in applying the DIM method successfully to full-scale aerospace vehicles.

Posted in: Briefs, Test & Measurement, Measurements, Vibration, Vibration, Aircraft, Spacecraft, Vehicle dynamics

Modules for Inspection, Qualification, and Verification of Pressure Vessels

This automated, modular, standardized system features interchangeable probes.

After decades of composite over-wrapped pressure vessel (COPV) development, manufacturing variance is still high, and has necessitated higher safety factors and additional mass to be flown on spacecraft, reducing overall performance. When liners are used in COPVs, they need to be carefully screened before wrapping. These flaws can go undetected and later grow through the thickness of the liner, causing the liner to fail, resulting in a massive leakage of the liner and subsequent mission loss.

Posted in: Briefs, Test & Measurement, Failure modes and effects analysis, Containers, Composite materials, Inspections, Spacecraft

In-Flight Pitot-Static Calibration

This precise yet time- and cost-effective method is based on GPS technology using output error optimization.

NASA’s Langley Research Center has developed a new method for calibrating pitot-static air data systems used in aircraft. Pitot-static systems are pressure-based instruments that measure the aircraft’s airspeed. These systems must be calibrated in flight to minimize potential error. Current methods — including trailing cone, tower fly-by, and pacer airplane — are time- and cost-intensive, requiring extensive flight time per calibration. NASA’s method can reduce this calibration time by up to an order of magnitude, cutting a significant fraction of the cost. In addition, NASA’s calibration method enables near-real-time monitoring of error in airspeed measurements, which can be used to alert pilots when airspeed instruments are inaccurate or failing. Because of this feature, the technology also has applications in the health usage and monitoring (HUMS) industry. Flight test engineers can be trained to use this method proficiently in 12 days without costly specialized hardware.

Posted in: Briefs, Test & Measurement, Calibration, Pitot-static instruments, Pitot-static instruments, Technician training, Test equipment and instrumentation

Magnetostrictive Pressure Regulating System

The regulator system offers precise operation with response times up to an order of magnitude faster than current technologies.

NASA’s Marshall Space Flight Center has developed a set of unique magnetostrictive (MS) technologies for utilization in pressure regulation and valve systems. By combining MS-based sensors with a newly designed MS-based valve, Marshall has developed an advanced MS regulator. This innovative approach provides both a regulator and a valve with rapid response times. In addition, the components are lightweight, compact, highly precise, and can operate over a wide range of temperatures and pressures. A prototype of the MS valve has been developed and NASA is seeking partners for licensure of this novel technology.

Posted in: Briefs, Instrumentation, Sensors and actuators, Sensors and actuators, Magnetic materials, Valves, Reliability, Reliability, Lightweighting

Shape Sensing Using a Multi-Core Optical Fiber Having an Arbitrary Initial Shape in the Presence of Extrinsic Forces

This technology can be used for aerospace safety, medical applications, robotics, and space exploration.

NASA’s Langley Research Center has demonstrated a patent-pending method and apparatus for determining the position, in three dimensions, of any point on an optical fiber. The new method uses low-reflectance Fiber Bragg Grating (FBG) strain sensors in a multicore fiber to determine how any point along that fiber is positioned in space. The characteristics of optical fibers and the FBGs vary with curvature, and by sensing the relative change of FBGs in each of three or more fiber cores, the three-dimensional change in position can be determined. By using this method in monitoring applications where optical fibers can be deployed — such as in structures, medical devices, or robotics — precise deflection, end position, and location can be determined in near real time. This innovative position detection method offers 10 times greater positional accuracy than comparable optical techniques.

Posted in: Briefs, Instrumentation, CAD / CAM / CAE, CAD, CAM, and CAE, Fiber optics, Sensors and actuators, Fiber optics, Sensors and actuators

Magnetic and Raman-Based Method for Process Control During Fabrication of Carbon-Nanotube-Based Structures

The methodology enables high quality and high yield with about 30% weight reduction over carbon composite materials.

NASA’s Langley Research Center has developed an innovative magnetic and Raman-based method for macroscopic process control during fabrication of carbon-nanotube-based structures. The development of super-strong, lightweight materials based on carbon nanotubes promises new materials with the strength of current carbon composite materials, but at substantially less weight. The development of these new materials is dependent upon nanotube quality, alignment, and load transfer between individual nanotubes in the structure. However, current fabrication process controls are limited to time-consuming microscopy testing at intermittent stages during processing. NASA’s innovative method can be applied during nanotube structure fabrication to obtain real-time feedback on critical processing parameters during fabrication. Moreover, the method is compatible with in-line fabrication processes.

Posted in: Briefs, Instrumentation, Fabrication, Composite materials, Lightweight materials, Nanotechnology, Quality control, Quality control

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