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Results for “LOADING APPARATUS”

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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Effect of sterilization irradiation on friction and wear of ultrahigh-molecular-weight polyethylene

The effect of sterilization gamma irradiation on the friction and wear properties of ultrahigh molecular weight polyethylene (UHMWPE) sliding against 316L stainless steel in dry air at 23 C was determined. A pin-on-disk apparatus was used. Experimental conditions included a 1-kilogram load, a 0.061- to 0.27-meter-per-second sliding velocity, and a 32000- to 578000-meter sliding distance. Although sterilization doses of 2.5 and 5.0 megarads greatly altered the average molecular weight and the molecular weight distribution, the friction and wear properties of the polymer were not significantly changed.

Jones, W. R., Jr.↗
NASA NTRS1982

Blockage and flow studies of a generalized test apparatus including various wing configurations in the Langley 7-inch Mach 7 Pilot Tunnel

A 1/12th scale model of the Curved Surface Test Apparatus (CSTA), which will be used to study aerothermal loads and evaluate Thermal Protection Systems (TPS) on a fuselage-type configuration in the Langley 8-Foot High Temperature Structures Tunnel (8 ft HTST), was tested in the Langley 7-Inch Mach 7 Pilot Tunnel. The purpose of the tests was to study the overall flow characteristics and define an envelope for testing the CSTA in the 8 ft HTST. Wings were tested on the scaled CSTA model to select a wing configuration with the most favorable characteristics for conducting TPS evaluations for curved and intersecting surfaces. The results indicate that the CSTA and selected wing configuration can be tested at angles of attack up to 15.5 and 10.5 degrees, respectively. The base pressure for both models was at the expected low level for most test conditions. Results generally indicate that the CSTA and wing configuration will provide a useful test bed for aerothermal pads and thermal structural concept evaluation over a broad range of flow conditions in the 8 ft HTST.

Albertson, C. W.↗
NASA NTRS2003

System for Centering a Turbofan in a Nacelle During Tests

A feedback position-control system has been developed for maintaining the concentricity of a turbofan with respect to a nacelle during acoustic and flow tests in a wind tunnel. The system is needed for the following reasons: Thermal and thrust loads can displace the fan relative to the nacelle; In the particular test apparatus (see Figure 1), denoted as a rotor-only nacelle (RAN), the struts, vanes, and other stator components of a turbofan engine that ordinarily maintain the required concentricity in the face of thermal and thrust loads are not present; and The struts and stator components are not present because it is necessary to provide a flow path that is acoustically clean in the sense that the measured noise can be attributed to the fan alone. The system is depicted schematically in Figure 2. The nacelle is supported by two struts attached to a two-axis traverse table located outside the wind-tunnel wall. Two servomotors acting through 100:1 gearboxes drive the table along the Y and Z axes, which are perpendicular to the axis of rotation. The Y and Z components of the deviation from concentricity are measured by four laser displacement sensors mounted on the nacelle and aimed at reflective targets on the center body, which is part of the fan assembly. The outputs of the laser displacement sensors are digitized and processed through a personal computer programmed with control software. The control output of the computer commands the servomotors to move the table as needed to restore concentricity. Numerous software and hardware travel limits and alarms are provided to maximize safety. A highly ablative rub strip in the nacelle minimizes the probability of damage in the event that a deviation from concentricity exceeds the radial clearance [<0.004 in. (<0.1 mm)] between the inner surface of the nacelle and the tips of the fan blades. To be able to prevent an excursion in excess of the tip clearance, the system must be accurate enough to control X and Y displacements to within 0.001 in. (.0.025 mm). One characteristic essential to such accuracy is sufficient rigidity in the mechanical components of the system to prevent excitation of vibrations in the strut/ nacelle subsystem. The need for such a high degree of accuracy prompted a comprehensive analysis of sources of measurement and control errors, followed by rigorous design efforts to minimize these errors. As a result, the design of the system incorporates numerous improvements in hardware, software, and operational procedures.

Cunningham, Cameron C.↗
NASA NTRS1976

Apparatus for positioning modular components on a vertical or overhead surface

An apparatus is disclosed for holding a plurality of modular components against a surface. A fixture prepositions the components and a vacuum develops a uniform pressure which presses and holds the fixture and objects against a surface. The surface may be curved, vertical, or overhead and since local load concentrations are avoided, fragile ceramic tiles may be installed using the apparatus.

Haynig, C. C.↗
NASA NTRS1990

Apparatus for measurement of thermal conductivity of insulation systems subjected to extreme temperature differences

Advanced aerospace designs require thermal insulation systems which are consistent with cryogenic fluids, high thermal loads, and design restrictions such as weight and volume. To evaluate the thermal performance of these insulating systems, an apparatus capable of measuring thermal conductivity using extreme temperature differences (27 to 1100 K) is being developed. This system is described along with estimates of precision and accuracy in selected operating conditions. Preliminary data are presented.

Dube, W. P.↗
NASA NTRS1971

Ballistic piston fissioning plasma experiment.

The production of fissioning uranium plasma samples such that the fission fragment stopping distance is less than the dimensions of the plasma is approached by using a ballistic piston device for the compression of uranium hexafluoride. The experimental apparatus is described. At room temperature the gun can be loaded up to 100 torr UF6 partial pressure, but at compression a thousand fold increase of pressure can be obtained at a particle density on the order of 10 to the 19th power per cu cm. Limited spectral studies of UF6 were performed while obtaining the pressure-volume data. The results obtained and their implications are discussed.

Miller, B. E.↗
NASA NTRS1981

Behavior of sulfur at high pressures and low temperatures

A new type of high-pressure apparatus for low-temperature experiments was built, which allows loading and measuring the load in situ at low temperature (1.5 K). It uses the diamond anvil in the flat-indentor configuration. It was used to investigate the high-conductivity state of sulfur at low temperatures. For pressures in the 50-GPa range, sulfur is still a semiconductor or at best a two phase semiconductor-metal system. As the temperature is lowered at 50 GPa, the resistance drops slightly, reaches a minimum around 230 deg K, and then increases dramatically.

Golopentia, D. A.↗
NASA NTRS1933

Dynamic Breaking Tests of Airplane Parts

The static stresses of airplane parts, the magnitude of which can be determined with the aid of static load assumptions, are mostly superposed by dynamic stresses, the magnitude of which has been but little explored. The object of the present investigation is to show how the strength of airplane parts can best be tested with respect to dynamic stresses with and without superposed static loading, and to what extent the dynamic strength of the parts depends on their structural design. Experimental apparatus and evaluation methods were developed and tried for the execution of vibration-strength tests with entire structural parts both with and without superposed static loading. Altogether ten metal spars and spar pieces and two wooden spars were subjected to vibration breaking tests.

Hertel, Heinrich↗
NASA NTRS1973

Apparatus and method for skin packaging articles

A system for skin packaging articles including a loading zone for positioning articles to be packaged upon a substrate, a thermoplastic film heating and vacuum operated skin packaging zone for covering the articles with film laminated to the substrate and a slitting zone for separating and trimming the individual skin packaged articles. The articles are passed to the successive zones. The loading zone may be adapted for conveyorized instead of hand loading. In some cases, where only transverse cutting of the film web is necessary, it may be desirable to eliminate the slitting zone and remove the skin packaged article or articles directly from the packaging zone. A conveniently located operating panel contains controls for effecting automatic, semiautomatic or manual operation of the entire system of any portions in any manner desired.

Madsen, B.↗
NASA NTRS1984

Portable pallet weighing apparatus

An assembly for use with several like units in weighing the mass of a loaded cargo pallet supported by its trunnions has a bridge frame for positioning the assembly on a transportation frame carrying the pallet while straddling one trunnion of the pallet and its trunnion lock, and a cradle assembly for incrementally raising the trunnion. The mass at the trunnion is carried as a static load by a slidable bracket mounted upon the bridge frame for supporting the cradle assembly. The bracket applies the static loading to an electrical load cell symmetrically positioned between the bridge frame and the bracket. The static loading compresses the load cell, causing a slight deformation and a potential difference at load cell terminals which is proportional in amplitude to the mass of the pallet at the trunnion.

Day, R. M.↗
NASA NTRS2014

Shake Test Results and Dynamic Calibration Efforts for the Large Rotor Test Apparatus

Prior to the full-scale wind tunnel test of the UH-60A Airloads rotor, a shake test was completed on the Large Rotor Test Apparatus. The goal of the shake test was to characterize the oscillatory response of the test rig and provide a dynamic calibration of the balance to accurately measure vibratory hub loads. This paper provides a summary of the shake test results, including balance, shaft bending gauge, and accelerometer measurements. Sensitivity to hub mass and angle of attack were investigated during the shake test. Hub mass was found to have an important impact on the vibratory forces and moments measured at the balance, especially near the UH-60A 4/rev frequency. Comparisons were made between the accelerometer data and an existing finite-element model, showing agreement on mode shapes, but not on natural frequencies. Finally, the results of a simple dynamic calibration are presented, showing the effects of changes in hub mass. The results show that the shake test data can be used to correct in-plane loads measurements up to 10 Hz and normal loads up to 30 Hz.

Large Rotor Test Apparatus↗
NASA NTRS1993

Friction and oxidative wear of 440C ball bearing steels under high load and extreme bulk temperatures

Unlubricated sliding friction and wear of 440C steels in an oxygen environment have been studied under a variety of load, speed, and temperature ranging from approximately -185 to 675 deg C. A specially designed test apparatus with a ball-on-flat geometry has been used for this purpose. The observed dependencies of the initial coefficient of friction, the average dynamic coefficient of friction, and the wear rate on load, speed, and test temperatures have been examined from the standpoint of existing theories of friction and wear. High contact temperatures are generated during the sliding friction, causing rapid oxidation and localized surface melting. A combination of fatigue, delamination, and loss of hardness due to tempering of the martensitic structure is responsible for the high wear rate observed and the coefficient of friction.

Chaudhuri, Dilip K.↗
NASA NTRS1987

Device for measuring hole elongation in a bolted joint

A device to determine the operable failure mode of mechanically fastened lightweight composite joints by measuring the hole elongation of a bolted joint is disclosed. The double-lap joint test apparatus comprises a stud, a test specimen having a hole, two load transfer plates, and linear displacement measuring instruments. The test specimen is sandwiched between the two load transfer plates and clamped together with the stud. Spacer washers are placed between the test specimen and each load transfer plate to provide a known, controllable area for the determination of clamping forces around the hole of the specimen attributable to bolt torque. The spacer washers also provide a gap for the mounting of reference angles on each side of the test specimen. Under tensile loading, elongation of the hole of the test specimen causes the stud to move away from the reference angles. This displacement is measured by the voltage output of two linear displacement measuring instruments that are attached to the stud and remain in contact with the reference angles throughout the tensile loading. The present invention obviates previous problems in obtaining specimen deformation measurements by monitoring the reference angles to the test specimen and the linear displacement measuring instruments to the stud.

Wichorek, Gregory R.↗
NASA NTRS1987

Dynamic characterization of viscoelastic polymer solutions in a lubricated cylinder - Plate apparatus

The characterization of several viscoelastic lubricants which are oil or water based has been studied in an apparatus consisting of a lubricated cylinder-plate contact. The friction loads were measured as a function of speed. The experimental results show the influence of the molecular weight and of the concentration of the polymeric additive as well as the influence of the viscosity of the oil-base on the load and friction coefficient. Also a test for mechanical degradation was performed on the polymer solutions. Several additives can favor a viscoelastic lubrication.

Doremus, P.↗
NASA NTRS1992

Apparatus for Elevated Temperature Compression or Tension Testing of Specimens

In order to support materials selection for the next generation supersonic civilian passenger transport aircraft, a testing apparatus was developed to evaluate certain materials under conditions of high load and elevated temperature. In order to elevate the temperature of the material during standard tension and compression testing the test specimen is surrounded by a pair of supports which include internal heating means. These supports also prevent buckling of the specimen during compression testing.

Gates, Thomas S.↗
NASA NTRS2006

Multistage Electrophoretic Separators

A multistage electrophoresis apparatus has been invented for use in the separation of cells, protein molecules, and other particles and solutes in concentrated aqueous solutions and suspensions. The design exploits free electrophoresis but overcomes the deficiencies of prior free-electrophoretic separators by incorporating a combination of published advances in mathematical modeling of convection, sedimentation, electro-osmotic flow, and the sedimentation and aggregation of droplets. In comparison with other electrophoretic separators, these apparatuses are easier to use and are better suited to separation in relatively large quantities characterized in the art as preparative (in contradistinction to smaller quantities characterized in the art as analytical). In a multistage electrophoretic separator according to the invention, an applied vertical steady electric field draws the electrically charged particles of interest from within a cuvette to within a collection cavity that has been moved into position of the cuvette. There are multiple collection cavities arranged in a circle; each is aligned with the cuvette for a prescribed short time. The multistage, short-migration-path character of the invention solves, possibly for the first time, the fluid-instability problems associated with free electrophoresis. The figure shows a prototype multistage electrophoretic separator that includes four sample stations and five collection stages per sample. At each sample station, an aqueous solution or suspension containing charged species to be separated is loaded into a cuvette, which is machined into a top plate. The apparatus includes a lower plate, into which 20 collection cavities have been milled. Each cavity is filled with an electrophoresis buffer solution. For the collection of an electrophoretic fraction, the lower plate is rotated to move a designated collection cavity into alignment with the opening of the cuvette. An electric field is then applied between a non-gassing electrode in the collection cavity and an electrolyte compartment, which is separated from the cuvette by a semipermeable membrane. The electrolyte is refreshed by circulation by use of a peristaltic pump. In subsequent steps, the lower plate is rotated to collect other electrophoretic fractions. Later, the collected fractions are removed from the collection cavities through ports that have threaded plugs. The base of the apparatus contains power supplies and a computer interface. The design includes provisions for monitoring and feedback control of cavity position, electric field, and temperature. The operation of the apparatus can easily be automated, as demonstrated by use of software that has already been written for this purpose.

Thomas, Nathan↗