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At least 109 records · Page 6

All sources NASA NTRS DOE OSTI

NASA NTRS1994

Liner mounting assembly

A mounting assembly includes an annular supporting flange disposed coaxially about a centerline axis which has a plurality of circumferentially spaced apart supporting holes therethrough. An annular liner is disposed coaxially with the supporting flange and includes a plurality of circumferentially spaced apart mounting holes aligned with respective ones of the supporting holes. Each of a plurality of mounting pins includes a proximal end fixedly joined to the supporting flange through a respective one of the supporting holes, and a distal end disposed through a respective one of the liner mounting holes for supporting the liner to the supporting flange while unrestrained differential thermal movement of the liner relative to the supporting flange.

Halila, Ely E.↗

NASA NTRS2008

Critical Initial Flaw Size Analysis

An independent assessment was conducted to determine the critical initial flaw size (CIFS) for the flange-to-skin weld in the Ares I-X Upper Stage Simulator (USS). The USS consists of several "tuna can" segments that are approximately 216 inches in diameter, 115 inches tall, and 0.5 inches thick. A 6 inch wide by 1 inch thick flange is welded to the skin and is used to fasten adjacent tuna cans. A schematic of a "tuna can" and the location of the flange-to-skin weld are shown in Figure 1. Gussets (shown in yellow in Figure 1) are welded to the skin and flange every 10 degrees around the circumference of the "tuna can". The flange-to-skin weld is a flux core butt weld with a fillet weld on the inside surface, as illustrated in Figure 2. The welding process may create loss of fusion defects in the weld that could develop into fatigue cracks and jeopardize the structural integrity of the Ares I-X vehicle. The CIFS analysis was conducted to determine the largest crack in the weld region that will not grow to failure within 4 lifetimes, as specified by NASA standard 5001 & 5019 [1].

Dawicke, David S.↗

NASA NTRS2016

Photonic Waveguide Choke Joint with Absorptive Loading

A photonic waveguide choke includes a first waveguide flange member having periodic metal tiling pillars, a dissipative dielectric material positioned within an area between the periodic metal tiling pillars and a second waveguide flange member disposed to be coupled with the first waveguide flange member and in spaced-apart relationship separated by a gap. The first waveguide flange member has a substantially smooth surface, and the second waveguide flange member has an array of two-dimensional pillar structures formed therein.

Wollack, Edward J.↗

NASA NTRS1984

Skin-stiffener interface stresses in composite stiffened panels

A model and solution method for determining the normal and shear stresses in the interface between the skin and the stiffener attached flange were developed. An efficient, analytical solution procedure was developed and incorporated in a sizing code for stiffened panels. The analysis procedure described provides a means to study the effects of material and geometric design parameters on the interface stresses. These stresses include the normal stress, and the shear stresses in both the longitudinal and the transverse directions. The tendency toward skin/stiffener separation may therefore be minimized by choosing appropriate values for the design variables. The most important design variables include the relative bending stiffnesses of the skin and stiffener attached flange, the bending stiffness of the stiffener web, and the flange width. The longitudinal compressive loads in the flange and skin have significant effects on the interface stresses.

Wang, J. T. S.↗

NASA NTRS1990

Quick connect coupling

A coupling device has a transversely arranged, open-end groove in a flange attached to a pipe end. The groove in the flange receives a circumferentially arranged locking flange element on the other coupling member and permits alignment of the bores of the coupling members when the locking flange element is in the open end groove. Upon alignment of the bores of the coupling members, a trigger member is activated to automatically release a spring biased tubular member in one of the coupling members. The tubular member has a conical end which is displaced into the other coupling member to lock the coupling members to one another. A tensioning nut is threadedly movable on a coupling member so as to be moved into tightening engagement with the other coupling member.

Sprague, Benny B.↗

NASA NTRS1992

Dual-Roll Robotic Wrist-Joint Assembly

Compact robotic wrist-joint assembly includes two motor subassemblies providing two concentric output rotations about axis of wrist: outer output flange on front face of assembly rotated to, and held at, any predetermined roll angle within range of plus or minus 180 degrees, and inner output flange concentric with outer output flange capable of unlimited rotation relative to outer flange. Each motor subassembly includes concentric rotor and stator and harmonic drive.

Vranish, John M.↗

NASA NTRS1993

Soret diffusion: A possible cause of compositional heterogeneity within tektites

Although a terrestrial origin for tektites is well-established on geochemical evidence, the physical processes involved in tektite formation have been largely ignored by geochemists and petrologists. For example, two observations that potentially bear on the physics of their origin are the following: (1) The flange of an australite is often more heterogeneous than its core; and (2) microtektites are compositionally more diverse than tektites. The first observation contradicts the traditional view of flange formation since a second heating to super-liquidus temperatures during atmospheric re-entry should, by chemical diffusion and mixing, have tended to homogenize the melt as it flowed off the leading edge of the core to form the flange. Analyses of an australite flange have been performed by electron microprobe. The results of those analyses emphasize the magnitude of the heterogeneity, as well as the well-defined elemental correlations that may constrain the process responsible for it. The second observation that the bulk compositions of microtektites are more divers than the tektites within the same strewnfield is a well-known characteristic, for which no quantitative explanation has been offered. The current investigation has involved the analysis of 43 Australasian microtektites from the Wharton Basin by electron microprobe, as well as trace-element abundances on fifteen of these microtecktites by INAA.

Delano, J. W.↗

NASA NTRS1998

Integrated Thermal Insulation System for Spacecraft

An integrated thermal protection system (TPS) for a spacecraft includes a grid that is bonded to skin of the spacecraft, e.g., to support the structural loads of the spacecraft. A plurality of thermally insulative, relatively large panels are positioned on the grid to cover the skin of the spacecraft to which the grid has been bonded. Each panel includes a rounded front edge and a front flange depending downwardly from the front edge. Also, each panel includes a rear edge formed with a rounded socket for receiving the rounded front edge of another panel therein, and a respective rear flange depends downwardly from each rear edge. Pins are formed on the front flanges, and pin receptacles are formed on the rear flanges, such that the pins of a panel mechanically interlock with the receptacles of the immediately forward panel. To reduce the transfer to the skin of heat which happens to leak through the panels to the grid, the grid includes stringers that are chair-shaped in cross-section.

Kolodziej, Paul↗

NASA NTRS1999

Stress Analysis and Permeability Testing of Cryogenic Composite Feed Line

For the next generation Single-Stage-To-Orbit (SSTO) Reusable Launch Vehicle (RLV), the use of advanced composite materials is highly desirable and critical to the success of the mission. NASA Marshall Space Flight Center (MSFC) has been working with the aerospace industry for many years to develop and demonstrate the cryogenic composite propellant tanks and feed lines technologies. A 50.8-mm diameter composite feed line for the Clipper Graham (DCY.A) was developed and tested. The purpose of the program is to demonstrate the LH2 permeability, composite to composite and metal joints, as well as composite flange interface of the composite feed line. Stress analysis and permeability testing have been performed on this article. Recently, a larger composite feed line design is being investigated and developed at MSFC for potential use in future RLV. The diameter of the feed line is 203 mm and the overall length is approximately 2.2 meters. This one piece unlined feed line consists of three straight tubular sections joined by two 90 degree elbows. The material chosen is IM7/977-3 prepreg fabric. The lay-up pattern is [0/90, plus or minus 45]s and is built up to 18 plies to the flanges at both ends. A preliminary stress analysis has been conducted to identify potential critical stresses and to develop the finite element analysis (FEA) capability of composite feed lines. As expected, the critical stresses occurred at the rims of some flange holes and the onset of the tapered tubular sections. Further analysis is required to determine the loads, flange deflection, vibration, and combined maximum loads. Two permeability-testing apparatuses were also designed for both flat panel specimens and curved feed line sections after impact damage. A larger permeant gas exposed area is required to accurately determine the effect of impact damage on the permeability of the feed line materials. The flat panel tester was fabricated and assembled. Three test coupons were made of graphite/epoxy plain weave prepreg and unidirectional prepreg. The flow rate was calculated by measuring the change of manometer fluid height per unit time. The permeability of the coupons is then calculated according to Darcy's Law. The pressure increase due to the head rise in the manometer was not considered for the initial estimation. The result of the unidirectional composite coupon agreed with that obtained from the DC-XA feed line testing of a similar material. Further improvement on the design may be required to improve the accuracy and efficiency of permeability testing.

Chu, Tsuchin Philip↗

NASA NTRS1999

Debris protection cover assembly for cable connectors

A protective cover assembly for an end of a cable connector having a cable housing that encloses a plurality of connective pins or sockets and that satisfies all requirements for space applications. A connector body flange is formed at the extremity of a cable and is positioned so that it may register with a corresponding connector body flange on the end of a companion cable to which a connection is to be made, one cable end having cable lead pins and the companion cable end having lead sockets with which the pins register. A latch mechanism having a latch housing is received in the connector body flange and a crank connected to a manually rotatable cap actuates a spring-loaded latch element that is engageable with a connector body flange to secure or to release the cover assembly with the simple twisting motion of the cap, thereby simplifying the task of effecting coupling and decoupling of the cable ends.

Yovan, Roger D.↗

NASA NTRS2010

Low-Friction, Low-Profile, High-Moment Two-Axis Joint

The two-axis joint is a mechanical device that provides two-degrees-of-freedom motion between connected components. A compact, moment-resistant, two-axis joint is used to connect an electromechanical actuator to its driven structural members. Due to the requirements of the overall mechanism, the joint has a low profile to fit within the allowable space, low friction, and high moment-reacting capability. The mechanical arrangement of this joint can withstand high moments when loads are applied. These features allow the joint to be used in tight spaces where a high load capability is required, as well as in applications where penetrating the mounting surface is not an option or where surface mounting is required. The joint consists of one base, one clevis, one cap, two needle bearings, and a circular shim. The base of the joint is the housing (the base and the cap together), and is connected to the grounding structure via fasteners and a bolt pattern. Captive within the housing, between the base and the cap, are the rotating clevis and the needle bearings. The clevis is attached to the mechanical system (linear actuator) via a pin. This pin, and the rotational movement of the clevis with respect to the housing, provides two rotational degrees of freedom. The larger diameter flange of the clevis is sandwiched between a pair of needle bearings, one on each side of the flange. During the assembly of the two-axis joint, the circular shims are used to adjust the amount of preload that is applied to the needle bearings. The above arrangement enables the joint to handle high moments with minimal friction. To achieve the high-moment capability within a low-profile joint, the use of depth of engagement (like that of a conventional rotating shaft) to react moment is replaced with planar engagement parallel to the mounting surface. The needle bearings with the clevis flange provide the surface area to react the clevis loads/moments into the joint housing while providing minimal friction during rotation. The diameter of the flange and the bearings can be increased to react higher loads and still maintain a compact surface mounting capability. This type of joint can be used in a wide variety of mechanisms and mechanical systems. It is especially effective where precise, smooth, continuous motion is required. For example, the joint can be used at the end of a linear actuator that is required to extend and rotate simultaneously. The current design application is for use in a spacecraft docking-system capture mechanism. Other applications might include industrial robotic or assembly line apparatuses, positioning systems, or in the motion-based simulator industry that employs complex, multi-axis manipulators for various types of motions.

Lewis, James L.↗

NASA NTRS1971

Boron epoxy rocket motor case program

Three 28-inch-diameter solid rocket motor cases were fabricated using 1/8 inch wide boron/epoxy tape. The cases had unequal end closures (4-1/8-inch-diameter forward flanges and 13-inch-diameter aft flanges) and metal attachment skirts. The flanges and skirts were titanium 6Al-4V alloy. The original design for the first case was patterned after the requirements of the Applications Technology Satellite apogee kick motor. The second and third cases were designed and fabricated to approximate the requirements of a small Applications Technology Satellite apogee kick motor. The program demonstrated the feasibility of designing and fabricating large-scale filament-wound solid propellant rocket motor cases with boron/epoxy tape.

Stang, D. A.↗

NASA NTRS1985

Calibrating Droplet Generator for Pressurized Testing Vessel

Device helps to aline laser for droplet-sizing interferometer. Monodispersing Droplet Generator creates uniformly sized droplets. Laser source and receiver of interferometer alined and focused on droplets. MDG mounted in high-pressure flange on tank. Line extensions pass through flange to outside. Flange allows MDG to operate at high injector back pressures used for tests.

Defever, G. J.↗

NASA NTRS1984

Design, Fabrication and Test of Composite Curved Frames for Helicopter Fuselage Structure

Aspects of curved beam effects and their importance in designing composite frame structures are discussed. The curved beam effect induces radial flange loadings which in turn causes flange curling. This curling increases the axial flange stresses and induces transverse bending. These effects are more important in composite structures due to their general inability to redistribute stresses by general yielding, such as in metal structures. A detailed finite element analysis was conducted and used in the design of composite curved frame specimens. Five specimens were statically tested and compared with predicted and test strains. The curved frame effects must be accurately accounted for to avoid premature fracture; finite element methods can accurately predict most of the stresses and no elastic relief from curved beam effects occurred in the composite frames tested. Finite element studies are presented for comparative curved beam effects on composite and metal frames.

Lowry, D. W.↗

NASA NTRS1985

Self-locking double retention redundant full pin release

A double retention redundant pull pin release system is disclosed. The system responds to a single pull during an intentional release operation. A spiral threaded main pin is seated in a mating bore in a housing, which main pin has a flange fastened thereon at the part of the main pin which is exterior to the housing. Accidental release tends to rotate the main pin. A secondary pin passes through a slightly oversized opening in the flange and is seated in a second bore in the housing. The pins counteract against one another to prevent accidential release. A frictional lock is shared between the main and secondary pins to enhance further locking of the system. The secondary pin, in response to a first pull, is fully retracted from its bore and flange hole. Thereafter the pull causes the main pin to rotate free of the housing to release, for example, a parachute mechanism.

Killgrove, T. O.↗

NASA NTRS1988

Postbuckling of eccentric open-section stiffened composite panels

A numerical study of the postbuckling behavior of open-section stiffened composite compression panels is presented with emphasis on the effects of an anisotropic attached flange on results, the strain distribution near collapse, and the change of buckle pattern during postbuckling response. Results are obtained for a blade stiffened panel with orthotropic or anisotropic attached flanges from a new verison of STAGS, a general, branched shell, nonlinear computer program. Comparisons between these results indicate the effects of anisotropic flanges on the results. Elastic strain distributions are obtained from STAGS and indications are given about the collapse loads and modes of a particular panel. Change of buckle pattern is studied using STAGS and a special purpose computer program for long plates. Comparisons are made with experimental results.

Stein, Manuel↗

NASA NTRS1990

Static Pressure-Assisted Seal For Helium

Two-piece, all-metal, pressure-assisted static flange seal holds in pressurized helium satisfactorily at temperature of negative 80 degree F (negative 62 degree C). Installed between two flanges, then bolted together. New version includes one pressure-assisted metal sealing element held in place by metal plate and flanges. Certified for use in flight on helium joints of Space Shuttle main engine. Likely terrestrial applications include laboratory and industrial gas-distribution systems.

Stuck, Donald E.↗

NASA NTRS1993

Computation of strain energy release rates for skin-stiffener debonds modeled with plate elements

An efficient method for predicting the strength of debonded composite skin-stiffener configurations is presented. This method, which is based on fracture mechanics, models the skin and the stiffener with two-dimensional (2D) plate elements instead of three-dimensional (3D) solid elements. The skin and stiffener flange nodes are tied together by two modeling techniques. In one technique, the corresponding flange and skin nodes are required to have identical translational and rotational degrees-of-freedom. In the other technique, the corresponding flange and skin nodes are only required to have identical translational degrees-of-freedom. Strain energy release rate formulas are proposed for both modeling techniques. These formulas are used for skin-stiffener debond cases with and without cylindrical bending deformations. The cylindrical bending results are compared with plane-strain finite element results. Excellent agreement between the two sets of results is obtained when the second technique is used. Thus, from these limited studies, a preferable modeling technique for skin-stiffener debond analysis using plate elements is established.

Wang, J. T.↗