Analysis of webs of partial-tension-field beams subjected to lateral pressure loadings
Webs of partial-tension-field beams subjected to lateral pressure loadings
STRESS AND LOAD↗
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Design of thick honeycomb core structures
The demand for weight reduction in flight vehicles suggests the use of lightweight sandwich structures. Several factors must be considered to obtain minimum-weight sandwich constructions. High-strength thin facings combined with lightweight thick core can offer a highly efficient structure when careful consideration is given to practical proportions between facings and core, edge design details, and manufacturing techniques. This paper discusses design approaches to relatively thick-core sandwich constructions. 'A large cylindrical structure subjected to axial compression loading and panel-type structures requiring low deflection under transverse loads are briefly analyzed. The selection of structural adhesives for thick-core structures and manufacturing considerations also are discussed.
SANDWICH CONSTRUCTION↗
Roll diffusion bonding of titanium alloy panels
Roll diffusion bonding technique is used for fabricating T-stiffened panel assemblies from titanium alloy. The single unit fabrication exhibits excellent strength characteristics under tensile and compressive loads. This program is applied to structures in which weight/strength ratio and integral construction are important considerations.
Bennett, J.↗
Experimental investigation of the effect of general imperfections on the buckling of cylindrical shells
Imperfection survey data on cylindrical shells before and during axial compression loading up to buckling load
Arbocz, J.↗
Optimum design of columns supported by tension ties.
Optimum design based on weight of columns supported by tension ties, considering various configurations and compressive loads
Felton, L. P.↗
Adhesion between atomically pure metallic surfaces Final report
Metallic adhesion from compression loads resulting in plastic deformation
Keller, D. V., Jr.↗
Axisymmetric and cylindrical isostabiloids
Differential equations for compression loaded axisymmetric cylindrical structures
Hedgepeth, J. M.↗
Buckling of axisymmetric imperfect circular cylindrical shells under axial compression
Circular cylindrical shells with axisymmetric imperfections tested under axial compressive load, studying imperfection amplitude and wavelength effects on minimum buckling load
Muggeridge, D. B.↗
Correlation of uniaxial yielding and substructure in aluminum-stainless steel composites
Uniaxial yielding correlation with substructure in Al-stainless steel metal matrix composites, using compressive loading test
Lawley, A.↗
Application of high speed photography to the photoelastic analysis of structural stability problems
Circular cylindrical shell stability under axial compressive load, analyzing buckling process by high speed photographic recording of photoelastic isoclinic pattern changes
Tennyson, R. C.↗
Variational approaches to the natural frequencies of a clamped uniform beam-column
Natural frequency bounds for clamped beam with linearly varying compressive load and constant end load by Rayleigh-Ritz, Bazley-Fox second projection and Kato methods
Fauconneau, G.↗
Seal material development test program
A program designed to characterize an experimental fluoroelastomer material designated AF-E-124D, is examined. Tests conducted include liquid nitrogen load compression tests, flexure tests and valve seal tests, ambient and elevated temperature compression set tests, and cleaning and flushing fluid exposure tests. The results of these tests indicate the AF-E-124D is a good choice for a cryogenic seal, since it exhibits good low temperature sealing characteristics and resistance to permanent set. The status of this material as an experimental fluorelastomer is stressed and recommended. Activity includes definition and control of critical processing to ensure consistent material properties. Design, fabrication and test of this and other materials is recommended in valve and static seal applications.
Source record↗
Crack toughness evaluation of hot pressed and forged beryllium
Beryllium fracture toughness test specimens were fatigue cracked using reversed cycling with a compression load two to three times the tension load. In worked beryllium, textures may be produced which result in fatigue cracks that are out of plane with the starter notch. Specimens of hot pressed stock exhibited load displacement records which were nonlinear throughout their course. Fracture specimens of both hot pressed and forged stock showed essentially no reduction of thickness and the fracture surfaces were flat and normal to the load axis. However, the stress intensity factor at maximum load increased with decreasing thickness. Load-displacement and electric potential records for the hot pressed beryllium specimens exhibited several anomalies such as negative residual crack mouth displacements and a decrease in electrical potential with increasing load.
Jones, M. H.↗
Evaluation, construction and endurance testing of compression sealed pyrolytic boron nitride slot insulation
A high-temperature statorette, consisting of an iron-27 percent cobalt magnetic lamination stack and nickel-clad silver conductors, was tested with pyrolytic boron nitride slot insulation. Temperatures were measured in each test to determine characteristics of slot linear heat conductance from statorette conductors. Testing was carried out to temperatures of approximately 1500 F in a vacuum environment of 10-8 torr. Three assemblies were built and tested, each having a different room temperature slot clearance. The final statorette assembly was subjected to a 100-hour vacuum aging test at 1400 F followed by 25 thermal cycles. Temperature data from the three assemblies showed that decreasing slot clearance and increasing compression loading did enhance heat transfer. The temperature difference between slot and lamination at 1400 F increased 4 F during the thermal aging and an additional 10 F during the 25 thermal cycles.
Grant, W. L.↗
Optimum mass-strength analysis for orthotropic ring-stiffened cylinders under axial compression
An analysis was developed to calculate the minimum mass-strength curve for an orthotropic cylinder subjected to axial compressive loading. The analysis, which includes the effects of ring and stringer eccentricities, is in a general form so that various cylinder wall and stiffener geometries can be considered. Several different ring-stiffened orthotropic configurations were studied. The minimum mass-strength curves and the dimensions associated with these curves are presented for (in order of decreasing efficiency) a tubular double bead, a nonsymmetric double bead, a Z-stiffened skin, and a trapezoidal corrugation. A comparison of efficiencies of the configurations shows a tubular element cylinder to be more efficient than a 3-percent core-density honeycomb-sandwich cylinder. It was found that for an optimized Z-stiffened skin, the location of the Z-stiffeners (internal or external) made a negligible difference in efficiency.
Shideler, J. L.↗
Ultra high vacuum adhesion testing of NERVA engine materials
The primary objective of this research program was to determine the effects of surface cleaning and deliberate gaseous contamination on the adhesion behavior of selected candidate materials for use in the NERVA nuclear rocket engine program. Using a torsion balance technique, the relationship between the normal compressive load applied to crossed rod samples and the resultant contact resistance was used to ascertain the extent of adhesion under each set of experimental conditions. In addition to an evaluation of the static adhesion behavior of selected materials combinations, the experimental apparatus was modified to permit a similar investigation relating to the effects of specific tangential displacements of the sample wires, i.e., their sliding friction behavior. During the course of this subcontract, the materials combinations 440 C vs. 440 C. pyrographite vs ZTA graphite, Nbc (graphite) vs. Nbc (graphite), and Electrolize Inconel 718 vs. Au electroplated 302 S/S were evaluated.
Source record↗
Some applications of NASTRAN to the buckling of thin cylindrical shells with cutouts
The buckling of isotropic and waffle-stiffened circular cylinders with and without cutouts was studied using NASTRAN's Rigid Format 5 for the case of axial compressive loading. The results obtained for the cylinders without cutouts are compared with available reference solutions. The results for the isotropic cylinders containing a single circular cutout with selected radii are compared with available experimental data. For the waffle-stiffened cyclinder, the effect of two diametrically opposed rectangular cutouts was studied. A DMAP alter sequence was used to permit the necessary application of different prebuckling and buckling boundary conditions. Advantage was taken of available symmetry planes to formulate equivalent NASTRAN model segments which reduced the associated computational cost of performing the analyses. Limitations of the applicability of NASTRAN for the solution of problems with nonlinear characteristics are discussed.
Williams, J. G.↗
Fatigue testing device
Anti-buckling assembly prevents buckling of sheet metal fatigue specimen when axial compressive load is applied. It provides for cyclic heating and cooling of specimen during testing. Assembly permits tests at two locations on specimen. Device has ports for visual, optical, or photographic monitoring of fatigue crack propagation in test specimen.
Eichenbrenner, F. E.↗