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Results for “Thermal nondestructive evaluation”

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At least 145 records · Page 8

All sources NASA NTRS DOE OSTI

NASA NTRS1983

Fracture toughness/Young's modulus correlation for low-density fibrous silica bodies

Fracture toughness and static Young's modulus were measured for the low-density silic fiber materials used as tiles in the thermal protection system of the Space Shuttle. The fracture behavior was found to be in excellent agreement with a previously formulated micromechanical model and allowed both (density) classes of tile material to be correlated to a single function. A similar correlation was also found between strength and Young's modulus, which is the basis of a nondestructive evaluation test for these materials. It was shown that the value of Young's modulus determined from a dynamic test can be substantially greater than that determined in a static mechanical test. This effect must be taken into account in the correlation. Finally, it was also determined that these materials have significant variations in Kc, both within and between production units, so that the strength variability in these materials is dependent on both fracture toughness and flaw-size variations.

Green, D. J.↗

NASA NTRS2016

Nondestructive Evaluation of Adhesive Bonds via Ultrasonic Phase Measurements

The use of advanced composites utilizing adhesively bonded structures offers advantages in weight and cost for both the aerospace and automotive industries. Conventional nondestructive evaluation (NDE) has proved unable to reliably detect weak bonds or bond deterioration during service life conditions. A new nondestructive technique for quantitatively measuring adhesive bond strength is demonstrated. In this paper, an ultrasonic technique employing constant frequency pulsed phased-locked loop (CFPPLL) circuitry to monitor the phase response of a bonded structure from change in thermal stress is discussed. Theoretical research suggests that the thermal response of a bonded interface relates well with the quality of the adhesive bond. In particular, the effective stiffness of the adhesive-adherent interface may be extracted from the thermal phase response of the structure. The sensitivity of the CFPPLL instrument allows detection of bond pathologies that have been previously difficult-to-detect. Theoretical results with this ultrasonic technique on single epoxy lap joint (SLJ) specimens are presented and discussed. This technique has the potential to advance the use of adhesive bonds - and by association, advanced composite structures - by providing a reliable method to measure adhesive bond strength, thus permitting more complex, lightweight, and safe designs.

Haldren, Harold A.↗

DOE OSTI2021

Nondestructive Evaluation (NDE) of Cable Moisture Exposure using Frequency Domain Reflectometry (FDR)

This Pacific Northwest National Laboratory (PNNL) milestone report assesses the capability of frequency domain reflectometry (FDR) to determine electrical cable submergence using PNNL’s Accelerated and Real-Time Environmental Nodal Assessment (ARENA) cable/motor test bed. This work includes a review of relevant literature as well as experimental tests. Nuclear power facilities have experienced various electrical cable failures related to water exposure. The current industry response involves actions to de-water cable vaults, manholes, and other cable locations. These efforts require considerable expenditure of resources, which makes it desirable for the industry to have information on cable condition and history regarding their submergence and water exposure (Mantey 2012). Two tests that are gaining favor within the nuclear industry are time-domain reflectometry (TDR) and FDR. These are low-voltage nondestructive tests that can be applied at a cable end. Testing from the cable end is important because local inspection along the cable length is very difficult due to cables being routed within trays, conduits, underground, and through walls. Both TDR and FDR techniques have been shown to locate cable insulation damage due to thermal, radiation, and mechanical damage. FDR measurements are also more sensitive than TDR to temperature changes, low-bend radius bends, and cable contact with various materials, including conductive materials like steel and water. This work evaluates the feasibility to extend FDR testing to characterizing whether an electrical cable is submerged or not and where it may be submerged using PNNL’s ARENA cable/motor test bed.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

NASA NTRS2012

STS-133/ET-137 Tanking Test Photogrammetry Assessment

Following the launch scrub of Space Shuttle mission STS-133 on November 5, 2010, an anomalous condition of cracked and raised thermal protection system (TPS) foam was observed on the External Tank (ET). Subsequent dissection of the affected TPS region revealed cracks in the feet of two Intertank (IT) metallic stringers. An extensive investigation into the cause(s) and corrective action(s) for the cracked stringers was initiated, involving a wide array of material and structural tests and nondestructive evaluations, with the intent to culminate into the development of flight rational. One such structural test was the instrumented tanking test performed on December 17, 2010. The tanking test incorporated two three-dimensional optical displacement measurement systems to measure full-field outer surface displacements of the TPS surrounding the affected region that contained the stringer cracks. The results showed that the radial displacement and rotation of the liquid oxygen (LO2) tank flange changed significantly as the fluid level of the LO2 approached and passed the LO2 tank flange.

Oliver, Stanley T.↗

DOE OSTI2019

Narrow band photoacoustic lamb wave generation for nondestructive testing using candle soot nanoparticle patches

The generation of ultrasonic surface waves with a photoacoustic-laser-source has become useful for the noncontact nondestructive testing and evaluation (NDT&E) of materials and structures. In this work, a hybrid ultrasound based NDT&E method is proposed based on the photoacoustic-laser-source as a noncontact Lamb wave generator by incorporating a line-arrayed patterned candle soot nanoparticle-polydimethylsiloxane (CSNPs-PDMS) patch as the signal amplifier and with a narrow bandwidth. The CSNP-PDMS composite has been investigated as the functional patch for its laser energy absorption efficiency, fast thermal diffusion, and large thermoelastic expansion capabilities. The signal amplitude (in mW) from the CSNP-PDMS patch exhibits 2.3 times higher amplitude than the no patch condition and a narrower bandwidth than other conditions. Furthermore, improvement in the sensitivity is also achieved through the selection of the aluminum nitride sensing system. The overall combination of the Lamb wave generation and receiver-sensing system in this study is found to be very promising for a broad range of noncontact NDT&E applications.

Acoustic transducers↗

NASA NTRS1990

Thermal barrier coating evaluation needs

A 0.025 cm (0.010 in) thick thermal barrier coating (TBC) applied to turbine airfoils in a research gas turbine engine provided component temperature reductions of up to 190 C. These impressive temperature reductions can allow increased engine operating temperatures and reduced component cooling to achieve greater engine performance without sacrificing component durability. The significant benefits of TBCs are well established in aircraft gas turbine engine applications and their use is increasing. TBCs are also under intense development for use in the Low Heat Rejection (LHR) diesel engine currently being developed and are under consideration for use in utility and marine gas turbines. However, to fully utilize the benefits of TBCs it is necessary to accurately characterize coating attributes that affect the insulation and coating durability. The purpose there is to discuss areas in which nondestructive evaluation can make significant contributions to the further development and full utilization of TBCs for aircraft gas turbine engines and low heat rejection diesel engines.

Brindley, William J.↗

NASA NTRS1974

Preliminary nondestructive evaluation manual for the space shuttle

Nondestructive evaluation (NDE) requirements are presented for some 134 potential fracture-critical structural areas identified, for the entire space shuttle vehicle system, as those possibly needing inspection during refurbishment/turnaround and prelaunch operations. The requirements include critical area and defect descriptions, access factors, recommended NDE techniques, and descriptive artwork. Requirements discussed include: Orbiter structure, external tank, solid rocket booster, and thermal protection system (development area).

Pless, W. M.↗

NASA NTRS1978

A method for determining structural properties of RCC thermal protection material

A method was developed for evaluation and prediction of effects of oxidation of the graphitic substrate on structural properties of Reinforced Carbon-Carbon (RCC) thermal protection material. Test specimens of RCC material were exposed to successive periods of convective heating in a plasma-jet facility to simulate the chemical reactions of Shuttle atmospheric entry. After each period of testing, the test specimen mass loss and performance in a nondestructive flexure test were determined. A computational model of the RCC specimen was developed for the NASA Structural Analysis (NASTRAN) program and validated by comparison of calculated and experimental results of flexure tests. The elastic moduli and ultimate loads in tension and compression were then computed for various levels of substrate oxidation.

Wakefield, R. M.↗

NASA NTRS2000

WSTF Pyrovalve Test Program Status: 2000

Extensive propulsion and pyrotechnic testing has been in progress at NASA/JSC White Sands Test Facility (WSTF) since 1995, starting with the Mars Observer Propulsion and Pyrotechnics Corrective Action Test Program (MOCATP). The MOCATP has been concluded, but extensive pyrovalve testing plus research and development continues at WSTF. Our capability to accurately characterize pyrovalve combustion product blow-by into propellant systems, evaluate hydrazine and monomethylhydrazine (MMH) thermal decomposition initiated by blow-by, and characterize valve actuation operation, continues to be used and refined. Data from this and several low blow-by pyrovalves manufactured by Conax and other corporations continues to be evaluated as a potential corrective measure for blow-by induced propellant explosions. Additionally, new measurement techniques are being developed, advanced pyrovalve development is under-way, and nondestructive examination (NDE) methods are being developed to help ensure pyrovalve safety. Starting in 2000 these data are being formatted into a pyrovalve application and testing handbook. Near-term testing includes evaluation of 3/8-in. Conax pyrovalves and other commercially available valves; development of advanced pyrovalve subcomponent technology; investigation of NDE techniques to evaluate pyrovalve ram seals and real-time measurement of housing deformation; and investigation of pyrotechnically induced explosive hydrazine decomposition both through testing and modeling. Evaluation of 3/8-in. Conax valves is to include operational margin testing to be accomplished at the NASA Langley Research Center.

Saulsberry, Regor L.↗

NASA NTRS2014

Nondestructive Evaluation (NDE) for Inspection of Composite Sandwich Structures

Composite honeycomb structures are widely used in aerospace applications due to their low weight and high strength advantages. Developing nondestructive evaluation (NDE) inspection methods are essential for their safe performance. Flash thermography is a commonly used technique for composite honeycomb structure inspections due to its large area and rapid inspection capability. Flash thermography is shown to be sensitive for detection of face sheet impact damage and face sheet to core disbond. Data processing techniques, using principal component analysis to improve the defect contrast, are discussed. Limitations to the thermal detection of the core are investigated. In addition to flash thermography, X-ray computed tomography is used. The aluminum honeycomb core provides excellent X-ray contrast compared to the composite face sheet. The X-ray CT technique was used to detect impact damage, core crushing, and skin to core disbonds. Additionally, the X-ray CT technique is used to validate the thermography results.

Zalameda, Joseph N.↗

NASA NTRS2004

Assurance Technology Challenges of Advanced Space Systems

The initiative to explore space and extend a human presence across our solar system to revisit the moon and Mars post enormous technological challenges to the nation's space agency and aerospace industry. Key areas of technology development needs to enable the endeavor include advanced materials, structures and mechanisms; micro/nano sensors and detectors; power generation, storage and management; advanced thermal and cryogenic control; guidance, navigation and control; command and data handling; advanced propulsion; advanced communication; on-board processing; advanced information technology systems; modular and reconfigurable systems; precision formation flying; solar sails; distributed observing systems; space robotics; and etc. Quality assurance concerns such as functional performance, structural integrity, radiation tolerance, health monitoring, diagnosis, maintenance, calibration, and initialization can affect the performance of systems and subsystems. It is thus imperative to employ innovative nondestructive evaluation methodologies to ensure quality and integrity of advanced space systems. Advancements in integrated multi-functional sensor systems, autonomous inspection approaches, distributed embedded sensors, roaming inspectors, and shape adaptive sensors are sought. Concepts in computational models for signal processing and data interpretation to establish quantitative characterization and event determination are also of interest. Prospective evaluation technologies include ultrasonics, laser ultrasonics, optics and fiber optics, shearography, video optics and metrology, thermography, electromagnetics, acoustic emission, x-ray, data management, biomimetics, and nano-scale sensing approaches for structural health monitoring.

Chern, E. James↗

NASA NTRSDate not supplied

Near Infrared In-situ Measurements for the Detection of Keyhole Porosity in Autogenous Ti-6AL-4V Welds

Certification of additive manufactured metal parts requires nondestructive evaluation (NDE) to ensure build quality. NDE can be performed during the build process or post build. For large parts with complex geometries, post build NDE can be challenging. In-situ NDE potentially provides a way to perform the inspection layer by layer. This work explores the use of a high speed near infrared (NIR) camera that is focused in-line with a laser to obtain high spatial and temporal resolution thermal imagery of the melt pool and associated cooling areas. The thermal data is obtained during a laser melting process using Ti-6AL-4V plate and of particular interest is the detection of keyhole porosity. Keyhole porosity can result from non-optimal build conditions, such as excessive laser power at a given laser scanning speed, that creates an entrapped bubble. The NIR measured melt pool and cooling areas are processed to detect keyhole porosity. The results are compared to X-ray CT results for validation.

additive manufacturing↗

NASA NTRSDate not supplied

Near Infrared In-situ Measurements for the Detection of Keyhole Porosity in Autogenous Ti-6AL-4V Welds

Certification of additive manufactured metal parts requires nondestructive evaluation (NDE) to ensure build quality. NDE can be performed during the build process or post build. For large parts with complex geometries, post build NDE can be challenging. In-situ NDE potentially provides a way to perform the inspection layer by layer. This work explores the use of a high speed near infrared (NIR) camera that is focused in-line with a laser to obtain high spatial and temporal resolution thermal imagery of the melt pool and associated cooling areas. The thermal data is obtained during a laser melting process using a Ti-6Al-4V plate and of particular interest is the detection of keyhole porosity. Keyhole porosity can result from non-optimal build conditions, such as excessive laser power at a given laser scanning speed, that creates an entrapped bubble. The NIR measured melt pool and cooling areas are processed to detect keyhole porosity. The results are compared to X-ray CT results for validation. Small keyhole pores buried deep were not detectable with this technique, however, some larger subsurface elongated pores along with some open surface pores did show some promise for detectability.

additive manufacturing↗

NASA NTRS2002

Friction Stir Weld Inspection Through Conductivity Imaging Using Shaped Field MWM(Registered Trademark) - Arrays

Friction Stir Welds (FSW) of Al 2195-T8 and Al 2219-T8, provided by Lockheed Martin Michoud Operations, were inspected for lack-of-penetration (LOP) defects using a custom designed MWM-Array, a multi-element eddy-current sensor. MWM (registered trademark) electrical conductivity mapping demonstrated high sensitivity to LOP as small as 0.75 mm (0.03 in.), as confirmed by metallographic data that characterized the extent of LOP defects. High sensitivity and high spatial resolution was achieved via a 37-element custom designed MWM-Array allowing LOP detection using the normalized longitudinal component of the MWM measured conductivity. This permitted both LOP detection and correlation of MWM conductivity features with the LOP defect size, as changes in conductivity were apparently associated with metallurgical features within the near-surface layer of the LOP defect zone. MWM conductivity mapping reveals information similar to macro-etching as the MWM-Array is sensitive to small changes in conductivity due to changes in microstructure associated with material thermal processing, in this case welding. The electrical conductivity measured on the root side of FSWs varies across the weld due to microstructural differences introduced by the FSW process, as well as those caused by planar flaws. Weld metal, i.e., dynamically recrystallized zone (DXZ), thermomechanically affected zone (TMZ), heat-affected zone (HAZ), and parent metal (PM) are all evident in the conductivity maps. While prior efforts had met with limited success for NDE (Nondestructive Evaluation) of dissimilar alloy, Al2219 to Al2195 FSW, the new custom designed multi-element MWM-Array achieved detection of all LOP defects even in dissimilar metal welds.

Goldfine, Neil↗

NASA NTRS2011

The Effects of Foam Thermal Protection System on the Damage Tolerance Characteristics of Composite Sandwich Structures for Launch Vehicles

For any structure composed of laminated composite materials, impact damage is one of the greatest risks and therefore most widely tested responses. Typically, impact damage testing and analysis assumes that a solid object comes into contact with the bare surface of the laminate (the outer ply). However, most launch vehicle structures will have a thermal protection system (TPS) covering the structure for the majority of its life. Thus, the impact response of the material with the TPS covering is the impact scenario of interest. In this study, laminates representative of the composite interstage structure for the Ares I launch vehicle were impact tested with and without the planned TPS covering, which consists of polyurethane foam. Response variables examined include maximum load of impact, damage size as detected by nondestructive evaluation techniques, and damage morphology and compression after impact strength. Results show that there is little difference between TPS covered and bare specimens, except the residual strength data is higher for TPS covered specimens.

Nettles, A. T.↗

NASA NTRS2013

Common Practice Lightning Strike Protection Characterization Technique to Quantify Damage Mechanisms on Composite Substrates

To support FAA certification airworthiness standards, composite substrates are subjected to lightning direct-effect electrical waveforms to determine performance characteristics of the lightning strike protection (LSP) conductive layers used to protect composite substrates. Test results collected from independent LSP studies are often incomparable due to variability in test procedures & applied practices at different organizations, which impairs performance correlations between different LSP data sets. Under a NASA supported contract, The Boeing Company developed technical procedures and documentation as guidance in order to facilitate a test method for conducting universal common practice lightning strike protection test procedures. The procedures obtain conformity in future lightning strike protection evaluations to allow meaningful performance correlations across data sets. This universal common practice guidance provides the manufacturing specifications to fabricate carbon fiber reinforced plastic (CFRP) test panels, including finish, grounding configuration, and acceptable methods for pretest nondestructive inspection (NDI) and posttest destructive inspection. The test operations guidance elaborates on the provisions contained in SAE ARP5416 to address inconsistencies in the generation of damage protection performance data, so as to provide for maximum achievable correlation across capable lab facilities. In addition, the guidance details a direct effects test bed design to aid in quantification of the multi-physical phenomena surrounding a lightning direct attachment supporting validation data requirements for the development of predictive computational modeling. The lightning test bed is designed to accommodate a repeatable installation procedure to secure the test panel and eliminate test installation uncertainty. It also facilitates a means to capture the electrical waveform parameters in 2 dimensions, along with the mechanical displacement and thermal heating parameters which occur during lightning attachment. Following guidance defined in the universal common practice LSP test documents, protected and unprotected CFRP panels were evaluated at 20, 40 and 100KAmps. This report presents analyzed data demonstrating the scientific usefulness of the common practice approach. Descriptions of the common practice CFRP test articles, LSP test bed fixture, and monitoring techniques to capture the electrical, mechanical and thermal parameters during lightning attachment are presented here. Two methods of measuring the electrical currents were evaluated, inductive current probes and a newly developed fiberoptic sensor. Two mechanical displacement methods were also examined, optical laser measurement sensors and a digital imaging correlation camera system. Recommendations are provided to help users implement the common practice test approach and obtain LSP test characterizations comparable across data sets.

Szatkowski, George N.↗

NASA NTRS1991

Quantitative nondestructive evaluation: Requirements for tomorrow's reliability

Quantitative Nondestructive Evaluation (QNDE) is the technology of measurement, analysis, and prediction of the state of material/structural systems for safety, reliability, and mission assurance. QNDE has impact on everyday life from the cars we drive, the planes we fly, the buildings we work or live in, literally to the infrastructure of our world. Here, researchers highlight some of the new sciences and technologies that are part of a safer, cost effective tomorrow. Specific technologies that are discussed are thermal QNDE of aircraft structural integrity, ultrasonic QNDE for materials characterization, and technology spinoffs from aerospace to the medical sector. In each case, examples are given of how new requirements result in enabling measurement technologies, which in turn change the boundaries of design/practice.

Heyman, Joseph S.↗

NASA NTRSDate not supplied

Delamination Depth Imaging for Quasi-Static and Fatigue Load Testing Using Passive Thermography

Passive thermography is used to monitor small increases in temperature resulting from delamination damage formation in composite hat-stiffened panels during both quasi-static and fatigue loading. It has been observed that rapid damage formation produces heating. This is composed of two heat generation components. The first component is an instantaneous response due to an irreversible thermoelastic strain release. The second component is mechanical heating, at the interface of failure, due to fracture damage. This produces a transient rise in temperature as the heat diffuses to the surface. The first component defines the thermal start time for the transient response. A one-dimensional thermal model is fitted to the data pixel by pixel, to produce imagery of the damage depth. The results are compared to ultrasonic and X-ray CT data.

Passive thermography↗