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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

Technical Letter Report of Slow-Strain-Rate Tensile Tests on Irradiated Stainless Steels in a PWR Environment

Slow-strain-rate tensile (SSRT) tests have been performed on irradiated specimens in a simulated pressurized water reactor (PWR) environment. The samples are miniature tensile specimens of various austenitic stainless steels (SSs) with different thermal-mechanical treatments commonly used for reactor core internal components. Neutron irradiation was carried out in the BOR-60 reactor, a sodium-cooled, fast breeder reactor in Russia, at ~320°C. The damage doses of the specimens are 5, 10, and 48 dpa (displacements per atom). All irradiated materials show significant irradiation hardening and loss of ductility in the SSRT tests. The yield strengths of cold-worked are higher than that of solution-annealed samples at all doses up to 48 dpa. While the irradiation hardening seems to saturate between ~5 and ~10 dpa, the loss of ductility continues to increase above 10 dpa. Strain softening is also observed for all irradiated materials above 5 dpa. Fractographic examinations show that ductile dimple fracture is the dominant morphology for all SSRT tests in the PWR environment. Small areas of transgranular, mixed mode and cleavage fractures are seen on most fracture surfaces in PWR water tests. Intergranular cracking is also observed in 48-dpa Types 316 and 347 SSs. Cracking susceptibility of the tested materials was evaluated with fracture morphology and time to failure. In general, high-doses cold-worked SSs are more susceptible to transgranular cleavage cracking in the PWR environment. Solution-annealed Type 347 SS is susceptible to intergranular cracking at 45 dpa in the PWR environment.

Chen, Y.↗
NASA NTRSDate not supplied

High-Temperature Mechanical Tensile Testing of Unidirectional Sic/Sic Composites Using A Versatile Lamp Furnace

Silicon carbide (SiC) based ceramic matrix composites (CMCs) are of interest for high-temperature structural applications, including use in turbine engine components. To understand damage mechanisms and predict durability of these systems, in-depth knowledge of their behavior at ambient and high temperatures is necessary. A method for high temperature testing of SiC/SiC minicomposite specimens up to 1500oC in both tensile fast fracture and creep conditions to investigate their thermomechanical behavior will be presented. This method utilizes a novel radiation heat furnace, equipped with infrared lamps with ellipsoidal reflectors, to heat the specimen at the furnace center in user-defined atmospheres. The housing structure of the lamps allows for observation of the specimen during testing using optical methods and for conducting other experimental studies. The goal is to employ nondestructive health monitoring techniques in-situ, including acoustic emission (AE), electrical resistance (ER), and digital image correlation (DIC) to evaluate damage initiation and evolution in the minicomposite specimens during tensile testing. Results from mechanical testing and nondestructive techniques will be presented. Electron microscopy and X-ray micro-computed tomography were used to further characterize specimen damage after testing.

Aeronautics↗
DOE OSTI2014

ROLE OF SCALE FACTOR DURING TENSILE TESTING OF SMALL SPECIMENS

The influence of scale factor (tensile specimen geometry and dimensions) on mechanical test results was investigated for different widely used types of small specimens (SS-1, SS-2, SS-3, and SS-J3) and a set of materials. It was found that the effect of scale factor on the accurate determination of yield stress, ultimate tensile stress, and uniform elongation values was weak; however, clear systematic differences were observed and should be accounted for during interpretation of results. In contrast, total elongation values were strongly sensitive to variations in specimen geometry. Modern experimental methods like digital image correlation allow the impact of scale factor to be reduced. Using these techniques, it was shown that true stress true strain curves describing strain-hardening behavior were very close for different specimen types. The limits of miniaturization are discussed, and an ultra-miniature specimen concept was suggested and evaluated. This type of specimen, as expected, may be suitable for SEM and TEM in situ testing.

Gussev, Maxim N↗
DOE OSTI2018

Elevated temperature tensile tests on DU–10Mo rolled foils

We report that studies were completed to obtain tensile mechanical properties for uranium-10wt.% molybdenum (U-10Mo) foils which were subjected to four different thermomechanical processing conditions. U-Mo alloy foils are being investigated to support fuel conversion of high power research reactors from their current high enriched fuel form to a low enriched fuel form. Mechanical properties of the fuel foil have an effect on irradiation performance and fuel fabrication and therefore are required to support modeling and qualification of new low-enriched uranium monolithic fuel plate designs. The data contained in this document contributes to fuel qualification by fulfilling the requirement that physical properties related to fuel meat be established. It is expected that depleted uranium-10wt% Mo (DU–10Mo) mechanical behavior is representative of the low-enriched U10-Mo to be used in actual fuel plates; therefore DU–10Mo was studied to simplify material processing, handling, and testing requirements. In this report, the different thermomechanical treatments included variations of wrought hot and cold rolling reduction and post rolling annealing. Each of the four foils was hot rolled. After hot rolling reduction, three of the four foils were further reduced by cold rolling. One of the three was reduced a further 20% by cold rolling, and the remaining two were reduced 50% by cold rolling. Following cold rolling reduction, one of the two foils which had been reduced 50% by cold rolling was annealed at 650?°C. Performing this analysis allows assessment of the impact of foil fabrication history on the resultant tensile properties DU–10Mo fuel foils. Tensile properties of DU–10Mo at room temperature through approximately 400 °C determined from the tests conducted herein suggest the material is stronger and has lower ductility than what has been reported previously in the literature. The explanation for these differences has yet to be determined, but is likely related to differences in grain size and/or impurity content, and variation in fabrication history. At the highest temperatures tested (550 °C) better agreement between the values reported here and available literature was found. As expected, yield and ultimate tensile strength decreased with increasing test temperature. Generally, the yield stress for all foil processing conditions was found to be in the range of 1100 MPa for room temperature tests, and in the range of 200 MPa for tests conducted at 550 °C. Ultimate tensile stress was in the range of 1175 MPa at room temperature, decreasing to approximately 225 MPa at 550 °C. Lastly, elongation increased significantly, from 0 to 2% at room temperature to 50% or more for the tests at 550 °C.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
NASA NTRS1987

Baseline tensile tests of composite materials for LDEF (Long Duration Exposure Facility) exposure

Tensile specimens of five graphite fiber reinforced composite materials were tested at room temperature to provide baseline data for similar specimens exposed to the space environment in low-Earth orbit on the NASA Long Duration Exposure Facility. All specimens were 4-ply (+ or - 45 deg)s layups; at least five replicate specimens were tested for each parameter evaluated. Three epoxy-matrix materials and two polysulfone-matrix materials, several fiber volume fractions, and two sizes of specimen were evaluated. Stress-strain and Poisson's ratio-stress curves, ultimate stress, strain at failure, secant modulus at 0.004 strain, inplane shear stress-strain curves, and unidirectional shear modulus at .004 shear strain are presented.

Witte, William G.↗
NASA NTRS1960

An Evaluation of Some Current Practices for Short-Time Elevated-Temperature Tensile Tests of Metals

The effect of different testing practices on the short-time elevated-temperature tensile properties was determined for 2024-T3 aluminum-alloy, HM21A-T8 and HK31A-H24 magnesium-alloy, and 12 MoV stainless-steel sheet. Tests were made under single strain-rate and single head-speed conditions. A dual strain-rate test was also included. An evaluation of the effects of these practices is given for the tensile and yield strengths, the elongation in 2 inches, and the uniform elongation. The need for a uniform testing practice is demonstrated. Recommended practices suggested by different organizations are included.

Manning, Charles R., Jr.↗
DOE OSTI2022

Micro-tensile testing of the bond line in hot isostatic pressed aluminum

Considerable effort is being devoted to development and regulatory qualification of low enriched fuels for research and test reactors by many agencies worldwide. One promising fuel configuration being examined for United States higher power research and test reactors (USHPRRs) are plate-type fuels composed of a metallic uranium-molybdenum foil clad in an aluminum alloy. The two pieces of aluminum alloy cladding are bonded using a hot isostatic pressing method. The mechanical properties of the resulting bond line in the aluminum alloy cladding will vary by the HIP'ing parameters, requiring a need to characterize the bond line. Small scale mechanical testing can provide a path for evaluating the mechanical properties and deformation behavior of the bond line both prior to and following irradiation. Here, in this research, room temperature micro-tensile specimens of non-irradiated and irradiated samples containing an Al alloy (AA 6061) bond line were tested to evaluate its strength and deformation behavior. Observations indicated that the strain rate did not affect the deformation behavior or strength and most of the micro-tensile specimens failed in a ductile mode in grains around the bond line. There was no indication that the microstructural features from the bond line affected the mechanical properties of the micro-tensile specimens. An initial examination was performed on irradiated material but further systematic studies of the effects of irradiation can be performed in the future.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
NASA NTRS1986

Furnace for Tensile Testing of Flexible Ceramics

Ceramic cloth and thread tested quickly at temperatures up to 1,250 degree C. Tensile strengths of ceramic cloths and threads measured conveniently in new furnace at specified temperatures up to 1,250 degree C, using ordinary mechanical tester. Samples heated along part of their lengths in furnace slots. Interchangeable furnace chambers and matching heating elements sized to match size of tested ceramic material.

Smith, M.↗
DOE OSTI2026

The effect of dogbone sample size in the tensile testing of TATB-based plastic‑bonded explosive materials

Mechanical properties are of interest for many plastic‑bonded explosive (PBX) materials with tensile properties being of particular interest. Direct tensile measurements using dogbone-shaped samples are considered the gold standard, but they are fairly large, making testing more costly and less desirable from a safety perspective. We investigated whether the measured tensile strength depends on the dogbone specimen size, which to our knowledge, has not been reported in the literature for PBX materials. Understanding this should inform the feasibility of employing smaller samples and how sample size should be considered when comparing PBX dogbone values in the literature. The TATB-based PBX dogbone sample size was varied by (a) scaling all dimensions proportionally and (b) varying only the length of the samples. It was observed that the measured tensile peak stress (strength) was a function of the sample size, and was more dependent on the diameter (cross-sectional area) than the length of the samples. Since peak stress is calculated as peak force normalized to the diameter of the sample, one might not expect an explicit diameter dependence for the peak stress. Therefore, these results suggest there may be an additional strengthening effect as the sample diameter is increased.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1944

Tensile Tests of NACA and Conventional Machine-countersunk Flush Rivets

An investigation was conducted to determine and compare the tensile strength of NACA and conventional machine-countersunk flush rivets of several rivet-head angles and varying countersunk depth. The results of the investigation are presented in the form of curves that show the variation of the tensile strength of the rivet with the ratio of the sheet thickness to the rivet diameter. For the same rivet-head angle and for a given angle of c/d, the NACA rivets developed higher tensile strength than the conventional rivets.

RIVETS, COUNTERSUNK - NACA↗
NASA NTRS1944

Tensile Tests of Round-head, Flat-head, and Brazier-head Rivets

An investigation was conducted to determine the tensile strength of round-head (AN43C), flat-head(AN442), and brazier-head (AN4556) aluminum-alloy rivets because of the scarcity of information on the tensile strength of rivets. The results of the investigation are presented as curves that show the variation of the ratio of the tensile strength of the rivet to the tensile strength of the rivet crank with the ratio of the sheet thickness to the rivet diameter for the different types of rivet.

Schuette, Evan H↗
DOE OSTI2015

Tensile testing of Fe and FeCr nanowires using molecular dynamics simulations

Using molecular dynamics, we have studied the behaviour of cylindrical [001]-oriented Fe and FeCr nanowires under uniaxial tensile strain with both an embedded atom method (EAM) and a Tersoff-like bond order potential. The mechanical properties were analysed and the deformation mechanism was studied and compared between the potentials. The effects of chromium content and size of the wire were studied. Both potentials show elongation by deformation twinning in the 〈111〉/(211) system resulting in a significantly stiffer and stronger [110]-axial nanowire. The pure iron nanowires are elastically softer than bulk iron and an addition of chromium has both a softening and weakening effect. The bond order potential shows a strong dependence on chromium concentration, while the dependence is considerably weaker for the EAM potential.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗