| Strength of an Explosively-Formed Bond |
SEP 2006 |
30 pages |
| Authors:
William S. De Rosset; Daniel J. Snoha; Michael A. Minnicino; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
 | A test fixture used to determine the shear strength of an explosively-formed bond between a liner and gun tube is described. Tests were carried out in which the liner material yielded before the bond was broken. A finite-element analysis of the deformation indicated that the bond shear strength was in excess of 45 ksi. Internal stress measurements made by x-ray diffraction indicated the presence of residual hoop and radial stresses ... |
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| An Experimental Investigation into the Temperature Profile of a Compliant Foil Air Bearing |
MAY 2004 |
20 pages |
| Authors:
Kevin Radil; Michelle Zeszotek; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| A series of tests was performed to determine the internal temperature profile in a compliant bump-type foil journal air bearing operating at room temperature under various speeds and load conditions. The temperature profile was collected by instrumenting a foil bearing with nine, type K thermocouples arranged in the center and along the bearing's edges in order to measure local temperatures and estimate thermal gradients in the axial and circumferential directions. ... |
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| Room Temperature Characterization of a Magnetic Bearing for Turbomachinery |
OCT 2002 |
14 pages |
| Authors:
Gerald Montague; Mark Jansen; Andrew Provenza; Ralph Jansen; Ben Ebihara; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| Open loop, experimental force and power measurements of a three-axis, radial, heteropolar magnetic bearing at room temperature for rotor speeds up to 20,000 RPM are presented in this paper. The bearing, NASA Glenn Research Center's and Texas A&M's third generation high temperature magnetic bearing, was designed to operate in a 1000 deg. F (540 deg. C) environment and was primarily optimized for maximum load capacity. The experimentally measured force produced ... |
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| Quasi-static Tearing Tests of Metal Plating |
SEP 2002 |
|
| Authors:
Jeffrey C. Woertz; MASSACHUSETTS INST OF TECH CAMBRIDGE
|
 | Great effort is being focused on making the next generation of naval combatant ships more resistant to the effects of close-aboard explosions. The examination of the deformation modes in blast-loaded metal plating suggests that a physical model can be developed to simulate the force vs. displacement history produced by an impinging shock wave during the holing phase. Similar approaches have been successfully used to approximate damage due to grounding and ... |
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| High-Cycle Fatigue Testing of Turbine Blades Under Multiaxial Loading |
DEC 2001 |
82 pages |
| Authors:
Mohan Balan; Bart Bornhorst; Som R. Soni; Ming Xie; ADTECH SYSTEMS RESEARCH INC BEAVER CREEK OH
|
| Gas turbine engine blades are subjected to a centrifugal force in the radial direction and high frequency transverse excitation under operating conditions. A multiaxial loading machine was proposed in the present SBIR program to perform high-cycle fatigue testing on gas turbine engine blades. A GE F110 second stage fan blade was selected as the specimen for initial testing and design studies. The blade was modeled and analyzed using finite element ... |
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| Damage Assessment in TiB2 Ceramic Armor Targets |
NOV 2001 |
64 pages |
| Authors:
Nevin L. Rupert; William H. Green; Joseph M. Wells; Kevin J. Doherty; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
|
| The interaction between long rods and ceramics is only partially understood; however, this understanding is essential in the design of improved performance of impact-resistant materials and armor system design applications. The current work takes a preliminary look into the modem mythology surrounding the formation of radial cracking in ceramics during ballistic penetration. Tests were conducted using a 32-g tungsten alloy laboratory penetrator with a length to diameter ratio (L/D) = ... |
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| Effect of Confinement on the Mechanical Response of Composite Plastic Bonded Explosives |
FEB 2000 |
30 pages |
| Authors:
Donald A. Wiegand; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER PICATINNY ARSENAL NJ WARHEADS ENERGETICS AND COMBAT SUP
|
| The mechanical properties of composite explosives are being studied as a function of mechanical confinement and three techniques for confinement were used. These are: (a) a constant confining pressure obtained by oil immersion, (b) radial confinement of a cylindrical sample by a thick walled steel cylinder that surrounds the sample (negligible radial strain), and (c) radial confinement of thin wafers by the platen-sample friction. while ... |
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| Shock-Induced Damage in Rock and Concrete |
30 SEP 1999 |
45 pages |
| Authors:
Charles C. Liu; Thomas J. Ahrens; CALIFORNIA INST OF TECH PASADENA
|
| We have developed a technique for measuring the depth time history of rigid body penetration into brittle materials under a deceleration of ^10(exp 5) g. A series of 4140 steel projectile penetrations into 6-mixture mortar targets has been conducted in the velocity range of 100 to 500 m/s. Based on the experimental results, the target materials are damaged via compacting and brittle radial and lateral crack propagation ... |
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| Elastic Comparison of Four Thread Forms |
FEB 1998 |
29 pages |
| Authors:
G. P. O'Hara; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
|
| Previously, this author introduced the concept that all screw thread forms have a structural Characteristic Curve, which defines the basic stress concentration as a function of a radial stress in the joint. An additional set of characteristic curves is produced when the general stress field is considered. The standard analysis is for a single thread tooth, isolated from a long chain of identical teeth, that is computationally efficient and facilitates ... |
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| Improved Load Alleviation Capability for the KC-135 |
SEP 97 |
144 pages |
| Authors:
Adam L. Mortensen; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING
|
| The Air Force will greatly increase its use of Unmanned Aerial Vehicles (UAVs) in the next century and the latter part of this decade. These UAVs will require refueling like their manned counterparts. The KC-135 and the KC-10 are candidates to provide this refueling task. The KC-10 is equipped with an automatic load alleviation system on its refueling boom which minimizes radial loads at the receiver of the aircraft being ... |
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| Mechanics of Brittle-Matrix Composites |
AUG 1997 |
58 pages |
| Authors:
Ran Y. Kim; DAYTON UNIV OH RESEARCH INST
|
| Model brittle matrix composites (SiC fibers and borosilicate glass) demonstrated that good matrix cracking stress is achievable only when a good matrix interfacial bond exists. Improvement in this matrix cracking stress can be seen with increasing fiber volume and lowered radial residual compressive stress. The ability to measure the fiber-matrix normal interfacial strength in a composite was demonstrated using a model system in a cruciform sample geometry. An analytical model ... |
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| Application of Cavity Expansion Analysis to Penetration Problems |
JUL 97 |
165 pages |
| Authors:
S. Satapathy; TEXAS UNIV AT AUSTIN INST FOR ADVANCED TECHNOLOGY
|
| Cavity Expansion Analysis (CEA) is extended in three different areas: (a) analysis of ductile targets accounting for finite boundaries and finite ductility; (b) analysis of brittle ceramics considering the cracking and comminution behavior; (c) development of a new penetration model for metals to overcome limitations of the existing models. CEA is modified to account for a finite boundary and to incorporate the effects of finite ductility of metallic targets, which ... |
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| Fatigue Analysis of a Vessel Experiencing Pressure Oscillations |
MAR 97 |
22 pages |
| Authors:
Edward Trojano; John H. Underwood; Anthony Scalise; G. P. O'Hara; Daniel Crayon; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET WEAPONS LAB
|
| A pressure vessel, which was designed and tested under laboratory conditions for tens of thousands of cycles, failed in service after only a few cycles. Thousands of oscillatory pressure reversals were measured at each loading. However, the predominance of the stress amplitudes were well below the critical threshold values necessary to initiate fatigue cracking. Analysis demonstrated that the disparity between lab cycling and field loading conditions could not be explained ... |
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| Membrane and Bending Stresses in Pressurized Elliptical Cylinders: Analytical Solutions and Finite Element Models |
09 DEC 96 |
69 pages |
| Authors:
Charles D. Kuhl; TEXAS A AND M UNIV COLLEGE STATION COLL OF ENGINEERING
|
| This report addresses the analysis of stresses in a thin walled elliptical cylinder using both classical membrane theory, bending theory, and Finite Element Analysis. Numerous analytical solutions from six authors are presented and examined to determine the hoop stresses, bending stresses, and total stresses that arise when elliptical cargo tanks are subjected to uniform internal pressure. Two Finite Element Models were created and evaluated using quadratic beam and shell elements. ... |
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| Spherical Waves in Saturated Sand |
13 SEP 96 |
186 pages |
| Authors:
Paul R. Gefken; Alexander L. Florence; Mohsen Sanai; SRI INTERNATIONAL MENLO PARK CA
|
| The Naval Surface Warfare Center needs to develop the capability to determine numerically the characteristics of a propagating stress wave in saturated sand. To provide needed experimental data, SRI International performed precision experiments with the objective of measuring saturated sand material response resulting from the detonation of a spherical explosive charge. The instrumentation consisted of particle velocity gages as the primary measurement tool and stress gages as a secondary measurement ... |
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| Thermal Management Research Studies. Volume 3. Heat Pipe in High-G environment: Analysis, Design and Testing |
11 SEP 96 |
59 pages |
| Authors:
Rengasamy Ponnappan; UNIVERSAL ENERGY SYSTEMS INC DAYTON OH HUMAN FACTORS DIV
|
| This report presents the details of a spin table test facility developed for testing heat pipes and other heat transfer experiments under high acceleration conditions. A drive system capable of variable spin up and spin down acceleration rates to simulate aircraft G-forces encountered during flight maneuvers is described. Also included are details on calorimetric testing, remote computer control operation and multichannel data acquisition capabilities of the spin table. The effects ... |
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| Towed Array Strain-Sensing Noise Canceller. |
JUL 1996 |
|
| Authors:
Robert J. Hansen; Chen C. Ni; Hugh M. Fitzpatrick; DEPARTMENT OF THE NAVY WASHINGTON DC
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| Method and apparatus are disclosed for reducing breathing- wave induced noise in a liquid-tilled elongate hose housing a hydrophone array. The arrangement involves sensing radial strain induced in the hose wall by the breathing waves (created as the hose is drawn longitudinally through water) and subtracting a multiple of the sensed value thereof from the array hydrophone output. Arrangements for measuring the breathing-wave-induced wall strains include (1) relative phase shifts ... |
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| Static Cavity Expansion Model for Partially Confined Targets |
JAN 96 |
19 pages |
| Authors:
Y. Partom; TEXAS UNIV AT AUSTIN INST FOR ADVANCED TECHNOLOGY
|
| The cavity expansion model (CEM), originally proposed as an indentation theory, has been used extensively to estimate the resistance of targets to long rod penetration. In the classical model the target is infinite and the cavity is opened up from zero radius. In previous work we applied the classical approach to laterally finite targets and we ran into difficulty. The resistance came out as decreasing with cavity radius. To circumvent ... |
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| Cavity Dynamics for Long Rod Penetration |
JAN 96 |
21 pages |
| Authors:
Minhyung Lee; Stephan Bless; TEXAS UNIV AT AUSTIN INST FOR ADVANCED TECHNOLOGY
|
| Two analytical models for the crater size due to long rod penetrations are presented. The energy method is the first which, in a steady state penetration, relates the kinetic energy loss of a penetrator to the total energy deposited in the target. An equation of cavity dynamics is set up by assuming a radial motion in the target. This approach appears to provide an upper bound of the crater size ... |
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| A Closed-Form Dynamic Elasticity Solution to the Fluid/Structure Interaction Problem of a Two-Layer Infinite Viscoelastic Cylinder with Inner and Outer Fluid Loading Subject to Forced Harmonic Excitation |
29 DEC 95 |
264 pages |
| Authors:
Mark S. Peloquin; NAVAL UNDERSEA WARFARE CENTER NEWPORT DIV RI
|
| This report documents an exact closed-form solution to the problem of a two-layer viscoelastic solid infinite cylinder that is immersed in an infinite ideal inviscid fluid and contains an infinite ideal inviscid fluid within its diameter. The viscoelasticity is modeled with structural damping, which is incorporated by the use of a complex modulus of elasticity. The composite system is subject to forced harmonic vibration at the outer solid/fluid interface. The ... |
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| Compression Strength and Drop Test Performance of XM232 Case Assemblies |
DEC 95 |
20 pages |
| Authors:
S. Dyer; A. Faburada; K. Gallavan; M. Hoogendyk; P. Hui; ARMTEC DEFENSE PRODUCTS INC COACHELLA CA
|
| The MACS XM232 case must meet radial and axial compression strength requirements in order to be used in an autoloader system. This study measured XM232 radial and axial compression strengths to determine if the French proposed JBMQU requirements were met. The XM232 current design exceeds the French requirements for mini- mum radial compression strength of 160.5 Ib with 3.5-mm deformation and minimum axial compression strength of 91.67 Ib with 2-mm ... |
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| Recovering Elastic Moduli of Nonlinear Anisotropic Annular Membranes from Interior Measurements of Deformation and Pressure |
DEC 95 |
54 pages |
| Authors:
Arthur D. Cummings; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH
|
| We investigate the problem of inferring elastic moduli of nonlinearly elastic membranes from interior measurements of deformation and pressure. We begin by formulating a model of membrane deformation under a vertical force where the geometry of the membrane is star-like. The model makes no specification of the constitutive law by which stresses are calculated from applied strains. Under appropriate choice of the constitutive law and simplification of the geometry, we ... |
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| Calculations to Support the Design of a Seismic Source Test |
01 NOV 95 |
63 pages |
| Authors:
David M. O'Donnell; Michael W. McKay; SCIENCE APPLICATIONS INTERNATIONAL CORP SAN DIEGO CA
|
| Two numerical simulations were performed with the 2-D RAGE code to examine potential designs for a proposed seismic source test. The first calculation simulated the original design of the proposed SHIST test which was intended to demonstrate the use of near-source instrumentation developed in the HYDROPLUS program along with near-field seismic instrumentation to evaluate the seismic source function for hard rock. The calculation modeled the explosion of a 20-ton sphere ... |
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| Stress Distribution in Concentrically-Hollowed Thick-Walled Tubes Subjected to Uniform Radial Loading |
NOV 95 |
55 pages |
| Authors:
Boaz Avitzur; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
|
| Autofrettage is a manufacturing process whereby a thick-walled cylindrical pressure vessel is pressurized well beyond its elastic limit. This pressurization causes the tube's interior to undergo plastic deformation. Under such a loading, the radial component of the stress throughout the tube's wall thickness is compressive, while the tangential component is mainly tensile. In very thick-walled tubes with a significant plastically deformed inner sleeve, the tangential stress component near the bore ... |
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| Cavity Expansion Analysis of Brittle Materials |
JUL 95 |
17 pages |
| Authors:
Sikhanda Satapathy; Stephan Bless; TEXAS UNIV AT AUSTIN INST FOR ADVANCED TECHNOLOGY
|
| In this report, we show that the target resistance of brittle materials can be calculated accurately using spherical cavity expansion analysis and a conventional brittle material model. The stress field ahead of the tip of the penetrator is assumed to have spherical symmetry. The brittle material is modeled as an elastic material which cracks under tension. The cracked material is considered to be pulverized when it fails in compression, which ... |
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| The Relationship between Residual Stress and Hardness and the Onset of Plastic Deformation |
MAY 95 |
35 pages |
| Authors:
S. C. Schroeder; J. Frankel; A. Abbate; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
|
| The stress distribution in the wall of a hollow steel cylinder that had been autofrettaged varies from compressive at the inside diameter to tensile at the outside diameter. The question of how the Rockwell-C (Rc) hardness varies with residual stress was treated previously. In order to generalize the previously developed concepts, in this report the hardness in the wall was measured as a function of radial position using various hardness ... |
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| Observations of Star Fracture and Longitudinal Splitting in BIS 812 EMA and Q1N Submarine Construction Steels |
MAR 95 |
|
| Authors:
I. A. Burch; D. S. Saunders; DEFENCE SCIENCE AND TECHNOLOGY ORGANIZATION CANBERRA (AUSTRALIA)
|
| The tensile properties and fracture behaviour of two submarine construction steels, BIS 812 EMA and Q1N, have been studied. Their properties and fracture behaviour were measured over a wide range of test temperatures utilizing plain and notched tensile specimens. The yield strength of both materials was found to increase with decreasing temperature and the fracture surface appearance of these steels was also temperature dependent. Under certain conditions star fracture was ... |
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| Improved Hybrid Bearings |
DEC 94 |
129 pages |
| Authors:
Michael M. Dezzani; Philip K. Pearson; TORRINGTON CO CT
|
| Nitriding technology was determined to significantly enhance the performance of steel bearing rings coupled with silicon nitride balls. NBD-200 silicon nitride was tested in two different sized full scale bearing tests with two nitrided steel ring materials, M50 and M50 NiL. Test bearing sizes were 35mm bore radial bearings and 40mm bore thrust bearings. Results showed truly superior rolling contact fatigue life under conditions of thin film and contaminated lubricant. ... |
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| Development of Ball Bearing Dynamic Analysis Methods Including Life Prediction Methods for Ceramic or Metal Bearings |
APR 94 |
159 pages |
| Authors:
Crawford Meeks; Brian Murphy; Long Tran; AVCON ADVANCED CONTROLS TECHNOLOGY INC AGOURA HILLS CA
|
| An analytical ball bearing dynamics model was developed that rigorously models all of the significant kinematics, structural and dynamic effects. The model can analyze bearings of any material combination for the races, ball and ball cage. This model analyzes the stresses and deflections of the loaded elements due to (1) preload, (2) external axial, radial and moment loads, (3) centrifugal and gyroscopic ball loads. A rigorous six-degree-of- freedom model of ... |
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| Calculations via Successive Approximations of Stress and Strain Distribution in Thick-Walled Concentric Tubes Due to a Radial Temperature Gradient |
MAR 94 |
24 pages |
| Authors:
Boaz Avitzur; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
|
| When thick-walled tubes are subjected to radial temperature gradients, cooler portions of the tubes impose constraints on the thermal expansion of hotter segments. (For example, in an internally heated tube, outer portions of the tube contain the expansion of the inner layer.) Constraint of the thermal expansion results in triaxial stress and strain distributions. A sequence of successive approximations has been used to calculate such stress and strain fields, while ... |
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| A Constant-Depth Scratch Test for the Measurement of Adhesion at Film- Substrate Interfaces |
MAR 94 |
93 pages |
| Authors:
E. D. Secor; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| This thesis reviews the development of the constant-depth Scratch Test for determining the adhesive shear strength of thin film-substrate interfaces, and proposes refinements to the theoretical analyses and experimental approach which were developed earlier. Modifications were made to incorporate a change in indenter orientation (for a Vicker's pyramidal indenter) as a measure to minimize damage during scratching. Additionally, the model was expanded to include the use of a conical indenter. ... |
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| Bond Stress-Slip Characteristics of FRP Rebars |
FEB 94 |
51 pages |
| Authors:
L. J. Malvar; NAVAL FACILITIES ENGINEERING SERVICE CENTER PORT HUENEME CA
|
| The bond characteristics of four different types of glass fiber- reinforced plastic (GFRP) rebars with different surface deformations were analyzed experimentally. Local bond stress-slip data, as well as bond stress- radial deformation data, needed for constitutive modeling of the interface mechanics, were obtained for varying levels of confining pressure. In addition to bond stress and slip, radial stress and radial deformation were considered fundamental variables needed to provide for configuration-independent ... |
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| The Effects of Processing and Constituent Materials on Compressive Strength of Thick Composite Laminates |
AUG 93 |
42 pages |
| Authors:
H. T. Hahn; E. A. Kempner; J. Slaughter; CALIFORNIA UNIV LOS ANGELES DEPT OF MECHANICAL AEROSPACE AND NUCLEAR ENGINEER ING
|
| The objectives of this study pertain to both the processing of thick composites and the constituent materials used. The main objectives of the research are to identify the processing conditions that are responsible for fiber wrinkling in thick, filament-wound cylinders and to develop a process simulation model for filament winding of thick cylinders. Analysis-experiment correlation will be used to aid model development. Also, the effect of constituent materials on compressive ... |
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| A Finite Strain Ring Dynamical Model for Pneumatic Tires |
AUG 93 |
|
| Authors:
Ned J. Lindsley; WRIGHT LAB WRIGHT-PATTERSON AFB OH
|
| In this report, using the most general 'plane sections remain plane' rod theory and the continuum mechanics approach, the exact strain expressions for a shearable, extensible ring are derived. These expressions are non linear in terms of both the displacements and the geometry of the ring and are Taylor series approximated after their derivation. A linear viscoelastic stress-strain relationship is assumed. The radial stress is considered negligible. The model includes ... |
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| An Experimental and Analytical Study of TIP Clearance Effects in Axial Flow Compressors |
DEC 91 |
252 pages |
| Authors:
Ian N. Moyle; EXOTECH INC FREMONT CA
|
| An analytical and experimental study of the performance changes and flow effects of rotor tip clearance variation in axial flow compressors is presented. The analyses demonstrate that previously unrecognized loss characteristics and flow behavior trends can be identified in a wide range of published tests of clearance effects. The performance and flow data are correlated at constant power conditions or nondimensionally in terms of the test compressor's geometry and wall ... |
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| Plastic Instabilities and Their Consequences in Steels and Other High Strength Alloys. The Investigation of the Fracture of Titanium Alloys by In-situ and Analytical Microstructural Techniques |
01 SEP 91 |
81 pages |
| Authors:
Heinz G. Wilsdorf; VIRGINIA UNIV CHARLOTTESVILLE DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| Some frequently used commercial high strength alloys have a tendency to fail catastrophically despite their ductile fracture mode. Apparently, these alloys develop instabilities during deformation which lead to local shear. The local shear areas often trigger catastrophic failure due to near adiabatic heating. An understanding of these phenomena was the object of the research reported here. Ten high strength alloys have been studied as a function of strain rate. Specifically, ... |
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| Fracture Studies of Diamond Films on Silicon |
28 AUG 91 |
18 pages |
| Authors:
J. J. Mecholsky Jr.; Y. L. Tsai; W. R. Drawl; FLORIDA UNIV GAINESVILLE DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| Diamond coatings were prepared on silicon substrates for fracture studies. Two thicknesses of coatings were evaluated: 6 m and 12 m. The diamond films increased the strength of the silicon for the same size fracture initiating crack and thus caused an apparent toughness increase from 1.1 MPam 1/ 2 for the uncoated silicon to about 1.6 MPam 1/2 for the 12 m coated silicon. Fractography showed that the indentation impression ... |
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| Bond of Reinforcement Under Controlled Confinement |
JUN 91 |
|
| Authors:
L. J. Malvar; NAVAL CIVIL ENGINEERING LAB PORT HUENEME CA
|
| Twelve specimens were tested to determine the local bond stress-slip characteristics of a No. 6 rebar embedded in a 3-inch diameter concrete cylinder. Radial confining stress around the concrete specimen and radial deformation were assumed to be fundamental variables, together with bond stress and slip, needed to properly describe the interface behavior. Configuration independent bond stress-slip, relationships for a short five-lug embedded length were obtained for various degrees of confining ... |
|
| Static and Free-Vibrational Response of Semi-Circular Graphite-Epoxy Frames with Thin-Walled Open Sections |
MAR 90 |
217 pages |
| Authors:
J. S. Collins; Eric R. Johnson; VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG DEPT OF ENGINEERING SCIEN CE AND MECHANICS
|
| Experiments were conducted to measure the three-dimensional static and free vibrational response of two graphite-epoxy, thin-walled, open section frames. The frames are semi-circular with a radius of three feet, and one specimen has an I cross section and the other has a channel cross section. The flexibility influence coefficients were measured in static tests for loads applied at midspan with the ends of the specimens clamped. Natural frequencies and modes ... |
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| High Temperature Multiaxial Creep Testing of NIMONIC 115 |
JAN 90 |
|
| Authors:
L. W. Candler; ROYAL AEROSPACE ESTABLISHMENT FARNBOROUGH (UNITED KINGDOM)
|
| Materials in present day gas turbine components are known to operate under complex stress situations. In recent years much effort has been devoted to quantifying the state of stress in multiaxial geometries and to studying the deformation and rupture mechanisms involved. Little attention has however been paid to the practical aspects of multiaxial testing and to understanding the material behaviour under complex stress states. A high temperature multiaxial testing facility ... |
|
| Traction Modeling of Military Lubricants |
24 AUG 89 |
|
| Authors:
Pradeep K. Gupta; GUPTA (PRADEEP K) CLIFTON PARK NY
|
| Traction behavior of military lubricants is investigated by examining both classical Newtonian and more recently postulated visco-elastic effects in the experimental traction data. An estimate of the relevant rheological parameters is derived by curve fitting the experimental traction data to predictions of the analytical models. The development process consists of several steps: (1) a regression analysis of experimental viscosity data obtained by a high-pressure viscometer is first carried out to ... |
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| Mechanical Evaluation of the Differential Drum Concept for Optical Fiber Pay-Out |
JUL 89 |
|
| Authors:
Stephen C. Cayson; ARMY MISSILE COMMAND REDSTONE ARSENAL AL GUIDANCE AND CONTROL DIRECTORATE
|
| This report describes the design of a differential drum system for optical fiber pay-out. The critical design parameters, such as the stresses and deflections in high-speed machinery, are discussed and the equations that govern them are developed. These equations are then applied and two systems are designed which meet the requirements. (Author). |
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| The Tensile Strength of Ice Containing Cracks |
08 MAR 88 |
|
| Authors:
Erland M. Schulson; THAYER SCHOOL OF ENGINEERING HANOVER N H
|
| Experiments have established that long, sharp cracks reduce the uniaxial tensile strength of equiaxed and randomly oriented aggregates of fresh- water ice strained at 0.001/s at -10 C, and that this reduction is in keeping with the dictates of linear elastic fracture mechanics. On the other hand, short cracks or long cracks that have been blunted by creep deformation have no effect on strength. In the latter cases, the tensile ... |
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| Fatigue Life Prediction in Thick-Walled Cylinders with Complex Residual Stresses |
JUL 1987 |
26 pages |
| Authors:
s. L. Pu; P. C. Chen; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET WEAPONS LAB
|
| The large variation in stress intensity factors corresponding to various material models for a single, radial, straight-fronted crack in a pressurized, partially autofrettaged cylinder leads to a drastic difference in the fatigue life predictions. None of the predicted lives agree with experimental results. Possible explanations of the discrepancy are given and corresponding correction factors are introduced. The predicted lives based on ther corrected stress intensity ranges are reasonably close to ... |
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| Triaxial Testing of First-Year Sea Ice |
DEC 86 |
|
| Authors:
J. A. Richter-Menge; G. F. Cox; N. Perron; G. Durell; H. W. Bosworth; COLD REGIONS RESEARCH AND ENGINEERING LAB HANOVER NH
|
| This report presents the first series of conventional triaxial tests carried out on columnar first year sea ice samples obtained from the field and tested under controlled laboratory conditions using a large-capacity test machine. A total of 110 horizontal ice samples from Prudhoe Bay, Alaska, were tested on a closed-loop electro-hydraulic test machine at -10 C in unconfined and confined constant-strain-rate compression. The confined tests were conducted in a conventional ... |
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| On the Application of the Strain Energy Density Theory in Predicting Crack Initiation and Angle of Growth |
SEP 86 |
|
| Authors:
A. K. Wong; AERONAUTICAL RESEARCH LABS MELBOURNE (AUSTRALIA)
|
| Until recently, the one-parameter singular expression for stresses near a crack-tip was widely thought to be sufficiently accurate over a reasonable region for any geometry and loading conditions. This view has been fast changing due to the growing evidence that the inclusion of higher order terms can significantly affect the solution, particularly under certain biaxial loading conditions. In this context, the present paper examines the strain energy density criterion for ... |
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| A Fundamental Study of the Bonding of Thermal Barrier Coatings |
JUN 86 |
|
| Authors:
T. E. Mitchell; A. H. Heuer; CASE WESTERN RESERVE UNIV CLEVELAND OH DEPT OF METALLURGY AND MATERIALS SCIENCE
|
| Two layer thermal barrier coatings are currently being developed for extending the performance of nickel base superalloy gas turbine engines. The best materials reported to data comprise a Ni-Cr-A1-Y bond coat and a Y2O3 partially stabilized ZrO2 (Y-PSZ) thermal barrier coat. The Y level of both the bond coat and the thermal barrier coat have been studied empirically but the fundamental factors that govern optimization of the thermal barrier system ... |
|
| Equilibrium Analysis of Axially Loaded Cylindrical Inclusions |
30 MAY 86 |
|
| Authors:
C. C. Swan Jr.; D. F. Patch; PACIFICA TECHNOLOGY DEL MAR CA
|
| Calculational analyses have been performed to study the inclusion problem associated with right circular cylinders taken to be representative of gauge packages emplaced in geologic media. The analyses performed may be categorized as uniaxial quasi-static, where samples of geologic medium containing an inclusion are subjected to uniaxial strain. The resulting equilibrium stress fields are studied with variation of the constitutive properties of both the host medium and the inclusion, and ... |
|
| Evaluation of Two Polyimides and of an Improved Liner Retention Design for Self-Lubricating Bushings |
24 OCT 84 |
17 pages |
| Authors:
Harold E. Sliney; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH LEWIS RESEARCH CEN TER
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| Two different polyimide polymers were studied; in addition, the effectiveness of a design feature to improve retention of the self-lubricating composite liners under high load was evaluated. The basic bearing design consisted of a molded layer of chopped graphite-fiber-reinforced-polyimide (GFRPI) composite bonded to the bore of a steel bushing. The friction, wear, and the load carrying ability of the bushings were determined in oscillating tests at 25C, 260C, and 315C ... |
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| Stress Intensity Factors for a Circular Ring with Uniform Array of Radial Cracks of Unequal Depth |
JUN 1984 |
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| Authors:
s. L. Pu; ARMY ARMAMENT RESEARCH AND DEVELOPMENT CENTER WATERVLIET NY LARGE CALIBER WEAPON SYSTEMS LAB
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| The plane problem of a uniform array of unequal depth radial cracks originating at the internal boundary of a pressurized circular ring is considered. The 12-node quadrilateral isoparametric elements with collapsed singular elements around crack tips are used to compute stress intensity factors at crack tips. In a previous study of equal depth radial cracks, the weakest configuration is a ring with two diametrically opposed cracks. The current study shows ... |
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Reports by Keyword(s)
RADIAL STRESS
