Evaluation of electron-beam welded hollow balls for high-speed ball bearings
Hollow balls for high speed bearings by electron beam welding, describing full scale and rolling element fatigue tests
Coe, H. H.↗
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Combined high vacuum/high frequency fatigue tester
Apparatus permits application of significantly greater number of cycles or equivalent number of cycles in shorter time than conventional fatigue test machines. Environment eliminates problems associated with high temperature oxidation and with sensitivity of refractory alloy behavior to atmospheric contamination.
Honeycutt, C. R.↗
Low temperature flexure fatigue cryostat Patent
Cryostat for flexure fatigue testing of composite materials
Reece, O. Y.↗
Fatigue lives at 600 F of 120 millimeter bore ball bearings of AISI M-50, AISI M-1, and WB-49 steels
High temperature fatigue tests of steel ball bearings with synthetic paraffinic oil lubricant in low oxygen environment
Bamberger, E. N.↗
Rolling-element fatigue lives of through hardened bearing materials
Hardness and fatigue tests of steel bearing alloys
Parker, R. J.↗
High-Temperature, Low-Cycle Fatigue Behavior of Tantalum
High temperature, low cycle fatigue tests of tantalum in inert argon atmosphere
LaForce, R.↗
Thermal-fatigue resistance of 15 high- temperature alloys determined by the fluidized- bed technique
Thermal fatigue tests of high temperature Ni and Co base alloys by fluidized bed technique
Bizon, P. T.↗
Strain gage attachment by spot welding reduces the fatigue strength of Ti-6Al-4V, Rene 41, and Inconel X
Fatigue tests were conducted with constant-amplitude axial stresses in the ratio of minimum to maximum stress of 0.05 (R=0.05). Specimens with and without strain gages were tested at 21 C, and superalloy specimens with and without strain gages were tested at 21 C and 815 C.
Imig, L. A.↗
A tool for cutting ultra thin slits in metals
Tool produces slits of 0.0305 mm widths in materials up to RC 50 hardness, minimizes material waste and improves precision. Device may be used for general metal cutting and for producing simulated cracks in metal samples used in fatigue tests.
Mcmahon, W.↗
Effects of loading sequence for notched specimens under high-low two-step fatigue loading
The effects of loading sequence on crack-initiation period were investigated for notched aluminum-alloy specimens under high-low two-step loading with special emphasis on local cyclic stresses and strains at the notch root. Local stress and strain were determined by a procedure based on an equation proposed by Neuber which relates elastoplastic stress and strain at a notch. Local stress and strain were also measured experimentally to verify the Neuber equation. The effects of initial high load on the crack-initiation periods were demonstrated with notched specimens and were simulated in unnotched specimens fatigue tested with local stress sequences. An analysis of the results indicated that sequence effects were not caused solely by local residual stresses, as is usually assumed; the existence of a damaging effect, resulting from the high local strain cycles, was demonstrated. The sequence effects observed with notched specimens were interpreted as the combined result of residual stresses and high local strain cycles.
Crews, J. H., Jr.↗
Advanced airbreathing engine lubricants study with a tetraester fluid and a synthetic paraffinic oil at 492 K (425 F)
Groups of 120-mm-bore angular-contact ball bearings made from AISI M-50 steel were fatigue tested with a tetraester and a synthetic paraffinic oil at a bearing temperature of 492 K (425 F) in an air environment. Bearing life exceeded AFBMA-predicted (catalog) life by factors in excess of 4 and 10 for the tetraester and synthetic paraffinic fluids, respectively. The final viscosities after 500 hours of operation were 14 and 6 times the initial values, respectively. During the same time period, when the test oil is replaced at a rate approximating the replenishment rate in actual commerical engine usage, no significant increase in lubricant viscosity with time was observed.
Zaretsky, E. V.↗
Advanced Approaches to Fatigue Evaluation
Conference on fatigue test evaluation for aircraft structures
Source record↗
Practical aspects of designing for and evaluating structural integrity
The application of procedures for designing and evaluating structural integrity of various construction techniques is discussed. The fatigue performance improvement of the following conditions is described: (1) conical fasteners, (2) hole preparation, (3) interference fit, and (4) interference protection. The application of fatigue tests to determine fail-safe conditions is analyzed.
Peyrony, M.↗
Reliability improvement of 1 mil aluminum wire bonds for semiconductors, technical performance summary
The reliability of semiconductor devices as influenced by the reliability of wire bonds used in the assembly of the devices is investigated. The specific type of failure dealt with involves fracture of wire bonds as a result of repeated flexure of the wire at the heel of the bond when the devices are operated in an on-off mode. The mechanism of failure is one of induced fracture of the wire. To improve the reliability of a chosen transistor, one-mil diameter wires of aluminum with various alloy additions were studied using an accelerated fatigue testing machine. In addition, the electroprobe was used to study the metallurgy of the wires as to microstructure and kinetics of the growth of insoluble phases. Thermocompression and ultrasonic bonding techniques were also investigated.
Source record↗
Study to determine and analyze the strength of high modulus glass in epoxy-matrix composites
Glass composition research was conducted to produce a high modulus, high strength beryllium-free glass fiber. This program was built on the previous research for developing high modulus, high strength glass fibers which had a 5 weight percent beryllia content. The fibers resulting from the composition program were then used to produce fiber reinforced-epoxy resin composites which were compared with composites reinforced by commercial high modulus glass fibers, Thornel S graphite fiber, and hybrids where the external quarters were reinforced with Thornel S graphite fiber and the interior half with glass fiber as well as the reverse hybrid. The composites were given tensile strength, compressive strength, short-beam shear strength, creep and fatigue tests. Comments are included on the significance of the test data.
Bacon, J. F.↗
Silicon nitride used as a rolling-element bearing material
Rolling-element fatigue tests were conducted with hot-pressed silicon nitride to determine its ability to withstand concentrated contacts in rolling-element bearings. If hot-pressed silicon nitride is used for both balls and races, attention must be paid to fitting both shaft and bearing housing.
Parker, R. J.↗
Coatings for directional eutectics
Eleven coating systems based on MCrAlY overlay and diffusion aluminide prototypes were evaluated to determine their capability for protecting the gamma/gamma prime-delta directionally solidified eutectic alloy (Ni-20Cb-6Cr-2.5Al) in gas turbine engine applications. Furnace oxidation and hot corrosion, Mach 0.37 burner-rig, tensile ductility, stress-rupture and thermomechanical fatigue tests were used to evaluate the coated gamma/gamma prime-delta alloy. The diffusion aluminide coatings provided adequate oxidation resistance at 1144 K (1600 F) but offered very limited protection in 114 K (1600 F) hot corrosion and 1366 K (2000 F) oxidation tests. A platinum modified NiCrAlY overlay coating exhibited excellent performance in oxidation testing and had no adverse effects upon the eutectic alloy.
Felten, E. J.↗
Bending stresses in spherically hollow ball bearing and fatigue experiments
Spherically hollow balls of 21.7, 50.0, and 56.5 percent mass reduction were operated in ball bearings and in a five-ball fatigue tester with differing outcomes. Available theoretical and experimental treatments of stresses in spherically hollow balls are reviewed and compared. Bending stresses are estimated for these spherically hollow balls to better understand the differences in ball bearing and fatigue test experience.
Nypan, L. J.↗