Ultrasonic analysis of cold-rolled aluminum
Shear wave refraction for ultrasonic detection of residual stress in cold-worked aluminum
RESIDUAL STRESS↗
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Results for “stress testing”
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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Polymers for spacecraft hardware Monthly technical progress report, 10 Jan. - 9 Feb. 1967
Polymeric materials for spacecraft application tested after curing and thermal vacuum exposure for weight loss and mechanical properties
SPACE ENVIRONMENT↗
Preliminary investigation of the mechanical behavior of three dimensionally reinforced plastics.
Multidirectional reinforced epoxy plastics in testing mechanical response to stress
EPOXY RESIN↗
Tensile testing grips ensure uniform loading of bimetal tubing specimens
Tensile testing grip uniformly distributes stresses to the internal and external tube of bimetal tubing specimens. The grip is comprised of a slotted external tube grip, a slotted internal tube grip, a machine bolt and nut, an internal grip expansion cone, and an external grip compression nut.
Driscol, S. D.↗
Use of wire lacing to reduce blade vibration in an axial-flow compressor rotor
Stress analysis and wear tests in use of lacing wire as vibration damper on turbocompressor blades
Hager, R. D.↗
Influence of salt and elevated-temperature exposure on the maximum compressive strength of titanium-alloy skin-stringer panels
Fabrication methods and tests for salt-stress corrosion and elevated temperature effects on compressive strength of titanium alloy skin stringer panels
Gardner, J. E.↗
Solid-state welding of TD-nickel bar
Solid state butt and lap joint welding of TD- nickel bar, evaluating performance by stress rupture and shear tests
Holko, K. H.↗
Feasibility of high voltage solar arrays
High voltage solar arrays, considering plasma power losses dielectric stresses design, fabrication and testing
Bayless, J. R.↗
A study of the required critical aspect ratio of fibers in composites intended for stress rupture applications
Critical aspect ratios of copper matrix and tungsten fibers in reinforced composites from stress-rupture and tension tests
Jech, R. W.↗
Effect of metallurgical structure and properties on adhesion and friction behavior of cobalt alloys
The metallurgical structure and some of the mechanical properties of two cobalt alloys, cobalt-50% iron and cobalt-25% molybdenum-10% chromium, were determined under various heat treated conditions. The mechanical properties of the bcc disordered Co-50Fe alloy, which was found to be very brittle, indicated an exceedingly low fracture strength, low hardness, and very weak grain boundary strength. Ordering by suitable heat treatment only produced a more brittle material with a lower fracture strength and a slightly higher hardness value. Work hardening was found to produce a finer grain structure and a greater grain boundary strength. Tensile properties were examined. It was found that the Co-25Mo-10Cr alloy was difficult to place in the alpha Co solid solution condition, which limited the ability to use precipitation as a hardening reaction. Over two hundred adhesion cycles from zero contact load, to maximum load, to fracture were conducted between couples for each of the above alloys in an ultrahigh vacuum system which would permit the sample surfaces to be cleaned of all contaminant layers. In the Co-50Fe case, the calculated fracture stress from the adhesion tests showed values in the range of 80 to 150 k.s.i., which is about ten times greater than the values from tension tests.
Keller, D. V., Jr.↗
ATM/cable arch and beam structural test program
The structural testing is described of an Apollo Telescope Mount (ATM) cable arch and beam assembly, using static loads to simulate the critical conditions expected during transportation and launch of the ATM. All test objectives were met. Stress and deflection data show that the assembly is structurally adequate for use in the ATM.
Housley, J. A.↗
Application of boron/epoxy reinforced aluminum stringers and boron/epoxy skid gear for the CH54B helicopter tail cone. Phase 2: Fabrication, inspection and flight test
A CH-54B Skycrane helicopter was fabricated with boron/epoxy reinforced stringers in the tail cone and boron/epoxy tubes in the tail skid. The fabrication of the tail cone was made with conventional tooling, production shop personnel, and no major problems. The flight test program includes a stress and vibration survey using strain gages and vibration transducers located in critical areas. The program to inspect and monitor the reliability of the components is discussed.
Welge, R. T.↗
Evaluation of Stress Corrosion Cracking Susceptibility Using Fracture Mechanics Techniques, Part 1
Stress corrosion cracking (SSC) tests were performed on 13 aluminum alloys, 13 precipitation hardening stainless steels, and two titanium 6Al-4V alloy forgings to compare fracture mechanics techniques with the conventional smooth specimen procedures. Commercially fabricated plate and rolled or forged bars 2 to 2.5-in. thick were tested. Exposures were conducted outdoors in a seacoast atmosphere and in an inland industrial atmosphere to relate the accelerated tests with service type environments. With the fracture mechanics technique tests were made chiefly on bolt loaded fatigue precracked compact tension specimens of the type used for plane-strain fracture toughness tests. Additional tests of the aluminum alloy were performed on ring loaded compact tension specimens and on bolt loaded double cantilever beams. For the smooth specimen procedure 0.125-in. dia. tensile specimens were loaded axially in constant deformation type frames. For both aluminum and steel alloys comparative SCC growth rates obtained from tests of precracked specimens provide an additional useful characterization of the SCC behavior of an alloy.
Sprowls, D. O.↗
Effects of sigma-phase formation on some mechanical properties of a wrought nickel-base superalloy (IN-100)
The effect of sigma phase formation on an extruded and forged nickel base superalloy with the composition of the casting alloy IN-100 was studied. By adding only aluminum and titanium to remelt stock, three compositions were produced which had varying propensities for sigma formation. These compositions were given a four step heat treatment and were stress-ruptured or tensile tested. The very sigma prone composition had a shorter rupture life than the sigma-free or moderately sigma prone compositions when tested at 843 and 885 C. Elongation in room temperature tensile tests was considerably lower for the very sigma prone composition than for the other two wrought compositions after prolonged exposure at 732 or 843 C.
Dreshfield, R. L.↗
Procedures for experimental measurement and theoretical analysis of large plastic deformations
Theoretical equations are derived and analytical procedures are presented for the interpretation of experimental measurements of large plastic strains in the surface of a plate. Orthogonal gage lengths established on the metal surface are measured before and after deformation. The change in orthogonality after deformation is also measured. Equations yield the principal strains, deviatoric stresses in the absence of surface friction forces, true stresses if the stress normal to the surface is known, and the orientation angle between the deformed gage line and the principal stress-strain axes. Errors in the measurement of nominal strains greater than 3 percent are within engineering accuracy. Applications suggested for this strain measurement system include the large-strain-stress analysis of impact test models, burst tests of spherical or cylindrical pressure vessels, and to augment small-strain instrumentation tests where large strains are anticipated.
Morris, R. E.↗
Time-dependent, non-Newtonian behavior of viscoelastic materials
A kinetic model for characterizing the shear stress or shear strain rate of thixotropic materials is developed and combined with Oldroyd's viscoelastic model (1953) modified in this paper in order to predict the first normal stress difference. In order to test the method, transient and steady state data have been obtained with a Weissenberg rheogoniometer used to measure the constant stress and constant shear rate of a solution of polymethyl methacrylate in diethylphthalate. A computer was used to facilitate data acquisition.
Jachimiak, P. D.↗
Inelastic micromechanics of curing stresses in composites
The combined finite element/laminate analysis method is used to study the thermal curing stresses in composite materials with a nonlinearly elastic matrix subject to creep. The application of this analysis to boron/epoxy composites shows that curing stress levels in the laminate are of sufficient magnitude to cause widespread yielding in the matrix. The stress levels, based on the creep analysis of a typical laminate cure cycle, indicate that the residual stresses can vary from 80 to 100% of the residual stress estimates based on linear thermoelastic analysis. It is shown that there is virtually no change in the static longitudinal or shear response of unidirectional and cross-ply boron/epoxy laminates as a result of curing stresses. Results of a series of constant-stress, high temperature creep tests are presented.
Foye, R. L.↗
Effect of thermal cycling in a Mach 0.3 burner rig on properties and structure of directionally solidified gamma/gamma prime-delta eutectic
An experimental study was carried out to evaluate the effect of cyclic thermal exposures on the mechanical properties of a gamma/gamma prime-delta eutectic alloy parallel to the growth direction. The alloy had a nominal composition by weight of Ni-20 Nb-6 Cr-2.5 Al and was directionally solidified at 3 cm/hr in a furnace with a thermal gradient of at least 200 C/cm. Bars of the alloy were exposed in a Mach 0.3 burner rig and cycled 300 times between 1100 and 425 C. Oxidation-erosion characteristics of the alloy were determined by weight loss measurements at 300-cycle intervals. After cyclic exposure, stress rupture and tensile tests were performed at both 760 and 1040 C. Microstructural changes from cyclic exposure were determined. Thermal cycling resulted in gamma prime coarsening and Widmanstaetten delta precipitation in the gamma phase. An unidentified precipitate, presumably gamma prime, was observed within the delta phase. These microstructural changes did not affect the mechanical properties of the eutectic. High oxidation-erosion weight loss rate was observed.
Gray, H. R.↗