| Non-Linear Finite Element Analyses of Composite Shells by Total Lagrangian Decomposition with Application to the Aircraft Tire |
MAR 96 |
280 pages |
| Authors:
James M. Greer Jr; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH
|
 | A total Lagrangian finite element scheme for arbitrarily large displacements and rotations is applied to a wide range of shell geometries. The scheme decomposes the deformation into stretches and rigid-body rotations, examining the deformed state with respect to an orthogonal, rigidly translated and rotated triad located at the point of interest on the deformed structure. The Jaumann stresses and strains, which are resolved along the axes of this triad, are ... |
|
| Undrained Creep Behavior of Clayey Soils |
MAR 96 |
341 pages |
| Authors:
Miguel Picornell; Soheil Nazarian; TEXAS UNIV AT EL PASO
|
| Clayey soils were used to prepare specimens possessing controlled pore solution chemistry. Specimens were consolidated and equilibrated at four different soil suction levels. Various specimens were subjected to creep/ recovery tests under drained and undrained conditions in conventional triaxial cells. The results were used to make comparisons with the behaviors predicted by a nonlinear viscoelastic model, based on power law, previously recommended by the parent project. Specimens of identical characteristics ... |
|
| Acrylic Light Pipes for Interior Illumination of Hyperbaric Chambers |
MAR 96 |
101 pages |
| Authors:
R. P. Johnson; NAVAL COMMAND CONTROL AND OCEAN SURVEILLANCE CENTER RDT AND E DIV SAN DIEGO CA
|
| The Naval Command, Control and Ocean Surveillance Center RDT&E division (NRaD) has developed a new acrylic plastic light pipe for hyperbaric chamber illumination that can be installed in pipe-sized penetrations in the wall of a hyperbaric chamber that provides improved optical, mechanical, and structural performance over commercial hardware. This new light pipe design has been qualified and accepted for service by the U.S. Navy community in man-rated hyperbaric chambers for ... |
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| Interation of a Swirling Jet With a Free Surface |
MAR 96 |
198 pages |
| Authors:
Michael S. Feyedelem; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| The turbulent flow field of a swirling jet issuing from a nozzle, beneath and parallel to a free surface has been studied in as much detail as possible using a three-component laser Doppler velocimeter and flow visualization. The results have shown that the swirl leads to the faster spreading and quicker mixing of the jet. For strongly swirling jets (S = 0.522), the similarity is not reached within ten diameters ... |
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| A Characterization of the Maximum Bending Stress of the Slice Hull in Random Seas |
MAR 96 |
142 pages |
| Authors:
Dennis W. McFadden; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| A study of the effects of speed, heading and sea state on the maximum longitudinal bending stress of the SLICE Advanced Technology Demonstrator is presented. Strip Theory is applied to a model of the SLICE hull. The hull is modeled using data from a current design and with ship loading weight information for ferry operations. Stress results are based on conventional beam theory applied to the hull girder. Bending moment ... |
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| Solution-Adaptive Calculation of Unsteady Blade Row Interactions in Transonic Turbomachinery |
MAR 96 |
232 pages |
| Authors:
Scott M. Richardson; WRIGHT LAB WRIGHT-PATTERSON AFB OH
|
| This report describes the development of an implicit, viscous method for the solution of the quasi-three-dimensional flow equations for rotor-stator interaction in transonic turbomachinery. The flow algorithm is described, followed by the implicit time-marching scheme, and the one-equation turbulence model. The algorithm is implemented on an unstructured grid arrangement of locally structured micro-blocks called 'patches.' Solution-dependent adaptation is used to refine the grid in regions containing flow features which require ... |
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| Modeling of Progressive Damage in Fiber-Reinforced Ceramic Matrix Composites |
MAR 96 |
336 pages |
| Authors:
James P. Solti; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING
|
| An analytic methodology is developed to model the response of fiber- reinforced ceramic matrix composites (CMOs) when subjected to monotonic and fatigue loadings. The analysis requires the formulation of (1) a micromechanics model which defines the laminate's geometry and constitutive relationship; (2) failure criteria which estimate the extent of microstructural damage, and, finally, (3) a means of analyzing frictional slip, fiber pull-out, interfacial wear and laminate failure. For the present ... |
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| Investigation of Fuselage Structure Subject to Widespread Fatigue Damage |
FEB 96 |
244 pages |
| Authors:
M. L. Gruber; C. J. Mazur; K. E. Wilkins; R. E. Worden; BOEING COMMERCIAL AIRPLANE CO SEATTLE WA
|
| Tbis report documents the results of the 'Investigation Of Fuselage Structure Subject To Widespread Fatigue Damage' contract. The primary program objective was to obtain data on airplane fuselage structures subject to multiple site damage (NlSD) in an environment that reflects typical commercial jetliner manufacturing and operating conditions. The program involves three technical tasks which include flat panel material characterization testing (Task I), Full- scale fuselage pressure panel testing (Task II) ... |
|
| Rheological Analysis of Silicone Pavement Joint Sealants |
FEB 96 |
212 pages |
| Authors:
Larry N. Lynch; ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MS GEOTECHNICAL LAB
|
| Joint sealant materials began to be widely used in pavement applications in an effort to protect the structural integrity of the pavement during the early 1940's. The protection was derived by minimizing moisture intrusion through the joint and preventing debris retention in the joint. Material specifications were soon developed to provide a means of material quality control. These specifications have evolved slowly over time, but they have not kept pace ... |
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| Experimental Evaluation of Pressure-Strain Models in Complex 3-D turbulent Flow Near a Wing/Body Junction |
FEB 96 |
158 pages |
| Authors:
M. S. Oelcmer; R. L. Simpson; VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG DEPT OF AEROSPACE AND OCE AN ENGINEERING
|
| Comparisons of experimentally-extracted pressure/rate-of-strain values were made to theoretical pressure-strain models for several locations of a wing-body function flow. The experimental pressure/rate-of-strain results were calculated from data obtained with a LDV technique. The data consist of profiles of mean velocity and higher order moments including quadruple products in a two- dimensional turbulent boundary layer (2DTBL), a strongly skewed three- dimensional turbulent boundary layer (3DTBL) in the vicinity of a 3-D ... |
|
| The REMR Bulletin. New from the Repair, Evaluation, Maintenance, and Rehabilitation Program. Volume 13, Number 1, February 1996 |
FEB 96 |
21 pages |
| Authors:
ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MS
|
|
| V-LAB: A Virtual Laboratory for Structural Integrity Assessment of Composite Components |
31 JAN 96 |
39 pages |
| Authors:
Eduardo Maos; Timothy R. Wyatt; APPLIED RESEARCH ASSOCIATES INC RALEIGH NC
|
| V-LAB is a Window's-based analysis tool for structural integrity assessment of composite components. The software allows failure investigators to work within 'virtual laboratories' representing different structural levels within a composite component. Data can be exchanged seamlessly between the different labs, allowing results to be easily integrated. A prototype of the V- LAB software system was developed with labs for micromechanics analysis, material definition, and failure analysis of composite laminates and ... |
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| Variability of Fatigue Crack Growth Properties for 2024-T3 Aluminium Alloy |
19 JAN 1996 |
36 pages |
| Authors:
A. Oldersma; R. J. Wanhill; NATIONAL AEROSPACE LAB AMSTERDAM (NETHERLANDS)
|
| Discussions between D-BAA and the NLR have shown that significant variability in fatigue crack growth properties is possible for the industry standard damage tolerant aluminum alloy, 2024-T3 sheet. This is important for two reasons: (1) design assumptions and (2) comparisons of different candidate materials, such as 6013-T6, with 2024-T3. Another important topic is the possibility of changes in damage tolerance properties owing to long term natural aging. In this report ... |
|
| The Immersed Fatigue Response of Polymer Composites |
02 JAN 96 |
28 pages |
| Authors:
L. V. Smith; Y. J. Weitsman; TENNESSEE UNIV KNOXVILLE DEPT OF MECHANICAL AND AEROSPACE ENGINEERING
|
| The effect of sea water on carbon/epoxy cross ply specimens is studied by consideration of fatigue data and failure modes. Tests were conducted using dry and saturated coupons fatigued in air, as well as pre-saturated coupons fatigued while immersed in sea water. The saturated coupons fatigued in air had the longest fatigue life, which was attributed to stress relief from sorption induced swelling. Saturated coupons fatigued in an immersed environment ... |
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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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| Characterization of Stiffening and Damping Materials for Planing Boat Shock Mitigation |
JAN 96 |
23 pages |
| Authors:
R. S. Peterson; COASTAL SYSTEMS STATION PANAMA CITY FL
|
| The occupants of high-speed planing boats operating in heavy seas are subject to repeated shock loads that can injure or impair performance. Identification and evaluation of shock mitigation concepts requires development of a nonlinear, time-domain, wave-to-wave elastic planing boat/human dynamic simulation. Shock mitigation concepts include the use of various stiffening and damping materials in the cockpit or within the hull structure. This report summarizes a general method for characterizing stiffening ... |
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| Deformation Behavior of Thin Lubricant Films at Elevated Pressure- Viscometric Functions |
JAN 96 |
32 pages |
| Authors:
Scott Bair; GEORGIA INST OF TECH ATLANTA SCHOOL OF MECHANICAL ENGINEERING
|
| Although normal stress differences in liquids have conventionally been associated with polymers, aspects of rheological behavior in lubricated concentrated contacts suggest that normal stress difference may be significant in even low molecular weight liquids sheared under high pressure and high shear stress. A torsional flow rheogoniometer was constructed for use at high (300 MPa) pressure. Four typical liquid lubricants were investigated, including one polymer/mineral oil solution. Shear stress and N1- ... |
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| Flutter Analysis and Analytic Sensitivities for Trapezoidal Panels |
96 |
96 pages |
| Authors:
David Mineau; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH
|
| Explicit expressions for the stiffness, geometric stiffness, mass, and aerodynamic force matrices are derived for the flutter analysis of simply supported composite wing panels. The formulation is based on Ritz analysis using simple polynomials and Piston Theory aerodynamics. The use of simple polynomials eliminates the need for numerical quadrature and decreases computation time. Analytic sensitivities of the aeroelastic system matrices and critical dynamic pressures are obtained with respect to layer ... |
|
| Constitutive Equations and Fracture Models for Sea Ice |
96 |
12 pages |
| Authors:
G. J. Rodin; R. A. Schapery; TEXAS UNIV AT AUSTIN DEPT OF AEROSPACE ENGINEERING AND ENGINEERING MECHANICS
|
| This final report summarizes research on deformation and fracture models for sea ice. In many cases results are compared with those for freshwater ice. Described first is work on modeling of primary creep for relatively short loading histories, studies on the applicability of linear elastic fracture mechanics to polycrystalline freshwater and sea ice, and finally a study on stress-transmission in polycrystals undergoing grain boundary sliding. Next, emphasis is on characterization ... |
|
| Analysis of Naturally Occurring Slip-Stick Data in Arctic Ice Floes |
96 |
43 pages |
| Authors:
Peter Michaux; INSTITUTE OF OCEAN SCIENCES SIDNEY (BRITISH COLUMBIA)
|
| Naturally occurring slip-stick data was recorded from a closing lead in the arctic in 1994. A portion of that data is analysed here with the idea of a slip-stick stress release model in mind. |
|
| A Fundamental Study of the Field Compressometer Test |
08 DEC 95 |
119 pages |
| Authors:
S. Banerjee; R. D. Holtz; UNIV OF WASHINGTON SEATTLE DEPT OF CIVIL ENGINEERING
|
| The project consisted of both theoretical and experimental research components. The theoretical research involved the development of a simple elasto-plastic constitative model based on incremental plasticity and double- hardening concepts to model the behavior of geomaterials. The model has been tested under general loading conditions and has reproduced experimental results reasonably well. I has also been implemented in a finite element program to facilitate the analysis of practical soil-structure interaction ... |
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| Simplified Micromechanical Models for Analysis of Interface Debonding in a Fibrous Composite |
DEC 95 |
115 pages |
| Authors:
Jia-Yuarn Guo; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| The objective of this study is to develop simplified micromechanical models to analyze the interface debonding between fiber and the matrix materials. Both analytical and simplified finite element models are used to predict the effective transverse elastic modules of fibrous composites with a partial interface crack based on the material properties of their constituents. The simplified finite element model uses springs in the connecting nodes between the fiber and matrix. ... |
|
| (D)ARPA Initiative in Concurrent Engineering (DICE). Phase 4: Tracked Vehicle Concurrent Engineering Tool Development, Integration, and Validation. Phase 5: Collaboration Technologies for Large-Scale Mechanical System Concurrent Engineering |
DEC 95 |
124 pages |
| Authors:
Kuang-Hua Chang; Joel Steele; Jun Tang; John Todtz; Chung-Shin Tsai; IOWA UNIV IOWA CITY CENTER FOR COMPUTER AIDED DESIGN
|
| This document constitutes the Final Report for the (D)ARPA Initiative in Concurrent Engineering (DICE) Phase 4 and Phase 5 research projects, Tracked Vehicle Concurrent Engineering Tool Development, Integration, and Validation and Collaboration Technologies for Large-Scale Mechanical System Concurrent Engineering, respectively, carried out at the Center for Computer Aided Design (CCAD), The University of Iowa. Applying basic concepts developed under prior phases of the DICE program, these and related research efforts ... |
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| Finite Element Modeling of Sandwich Composite Structures Subject to Low Velocity Impact and Delamination |
DEC 95 |
101 pages |
| Authors:
Gerald W. Wojcik; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| Two common concerns in the use of sandwich composite construction are the effects of low velocity impact and delamination upon structural failure. Finite element analysis of these events can provide a comprehensive time history of the resulting stress strain, displacement, and velocity at all points in a structure. The purpose of this research is to develop a finite element model of a sandwich composite and use this model to analyze ... |
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| Investigation of Residual Strength and Fatigue Life of Unstiffined Aluminum Panels with Multiple Site Damage. |
DEC 1995 |
147 pages |
| Authors:
Mark C. Cherry; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING
|
| Multiple Site Damage (MSD) is the occurrence of small fatigue cracks at several sites within aircraft structures. This is important since it may lower the residual strength and fatigue life of the structure beyond what can be predicted using the damage tolerance technique based on a single crack, currently in use to design aircraft structures. This study investigated the effects of MSD on unstiffined panels. MSD usually occurs at rivet ... |
|
| An Experimental Investigation of Organized Turbulent Motions and Wall- Pressure Fluctuations in Complex Flows |
DEC 95 |
147 pages |
| Authors:
Mark Kammeyer; NAVAL SURFACE WARFARE CENTER DAHLGREN DIV VA
|
| The relationship between high-amplitude wall-pressure peaks and near- wall flow structures has been studied for both equilibrium and disturbed turbulent boundary layers. The disturbed flow was that formed downstream of reattachment of the flow over an aft-facing step. In this case, the disturbances were primarily confined to the outer regions of the boundary layer. Simultaneous measurements of the fluctuating wall-pressure and the streamwise and wall-normal velocity were obtained. These measurements ... |
|
| Multidisciplinary Interactive Design and Analysis System - Architecture |
DEC 95 |
206 pages |
| Authors:
Harini S. Rajagopalan; Xiaodong Luo; Ramana V. Grandhi; WRIGHT STATE UNIV DAYTON OH DEPT OF MECHANICAL AND MATERIALS ENGINEERING
|
| This report presents the development of MIDAS, a graphical pre- and post-processor for ASTROS. The system is developed around I-DEAS using its Open Architecture. MIDAS displays structural responses like stresses, displacements under multiple boundary conditions and load cases. It also displays normal modes animation and concurrent aerodynamic and structural models. Present work concentrates on display of flutter modes, design optimization iteration histories and optimum variables distribution. What-if trade off studies ... |
|
| Guideline for Evaluation of Finite Elements and Results |
DEC 95 |
259 pages |
| Authors:
R. I. Basu; K. J. Kirkhope; J. Srinivasan; MIL SYSTEMS ENGINEERING OTTAWA (ONTARIO)
|
| Finite element analysis (FEA) is the most common structural analysis tool in use today. In marine industries, the use of this technique is becoming more widespread in the design, reliability analysis and performance evaluation of ship structures. Users of FEA have considerable freedom in designing the finite element model, exercising it and interpreting the results. Key components of this process include the selection of the computer program, the determination of ... |
|
| Optical Stress Gauge Development for Very High Stresses Piezoraman Measurements and Analysis |
01 NOV 95 |
235 pages |
| Authors:
Yogendra M. Gupta; WASHINGTON STATE UNIV PULLMAN DEPT OF PHYSICS
|
| Experiments and analyses were carried out to demonstrate the use of diamond crystals as very high stress, optical transducers under shock loading. Experimental methods were developed to routinely permit time-resolved measurements (10 ns resolution) of stress induced frequency shifts of the Raman line in shocked diamonds. Plate impact experiments were conducted to achieve peak stresses to 500 kbar for uniaxial strain compression along the 110 and 100 orientations. Over the ... |
|
| Large Deformation Analysis of Nonlinear Homogeneous and Heterogeneous Media Using an Adaptive Arbitrary Lagrangian-Eulerian Finite Element Method |
NOV 95 |
174 pages |
| Authors:
Somnath Ghosh; OHIO STATE UNIV COLUMBUS
|
| Research has been conducted to advance the state of the art in (a) multiple scale modeling of advanced heterogeneous materials, (b) in large deformation analysis of solids with applications in metal forming, and also (c) in solidification modeling. For modeling heterogeneous materials (a), a new Voronoi Cell finite element model has been developed which naturally evolves from the microstructure. Formulations have been developed for thermo-dasticity, elasto-plasticity and heat conduction. This ... |
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| Stress Concentrators and Rate Effects in Formation of Adiabatic Shear Bands |
NOV 95 |
2 pages |
| Authors:
J. R. Klepaczko; METZ UNIV (FRANCE) LAB OF PHYSICS AND MECHANICS OF MATERIALS
|
| This Abstract covers the second period of the Contract on behavior of stress concentrators in an alloy steel at high loading rates. During this period two researchers have been working on numerical analyses of stress concentrators at high loading rates and on the Critical Impact Velocity in shear. Both numerical studies by the Finite Element method (Abacus) are performed for VAR 4340 steel of hardness 52HRC. Available literature data have ... |
|
| U.S. Army Materiel Command (AMC) Field Assistance in Science and Technology-Jr. (FAST-JR) Project: Arctic Troop Cover (ATC) |
NOV 95 |
41 pages |
| Authors:
John A. Condon; Peter J. Fazio; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| The present troop cover for the 2.5-ton (M35A2) truck is an outdated design that is heavy and difficult to handle in the extreme cold weather of the arctic environment. The 2.5-ton truck is being replaced by the 5-ton (M923/ M939A2) truck, which at present has no provision for an arctic troop enclosure. There now exists a need for an arctic specification troop enclosure for the 5- ton truck that does ... |
|
| An Experimental Investigation of Nonlinear Behaviour of Beams and Plates Excited to High Levels of Dynamic Response |
31 OCT 95 |
470 pages |
| Authors:
Howard F. Wolfe; Cynthia A. Shroyer; Dansen L. Brown; Larry W. Simmons; WRIGHT LAB WRIGHT-PATTERSON AFB OH
|
| Dynamic tests were conducted utilizing clamped aluminium and composite beams and plates excited by shakers and acoustic progressive wave tubes. The total strains and the components, bending and axial and the displacements were measured with increasing levels of excitation. Bistable behaviour is observed with sinusoidal excitation for both the beams and plates. The beams randomly excited exhibit a slight frequency shift and peak broadening, which can be attributed to an ... |
|
| Experimental and Analytical Assessment of the Thermal Behavior of Spiral Bevel Gears |
18 OCT 95 |
22 pages |
| Authors:
Robert F. Handschuh; Thomas P. Kicher; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH LEWIS RESEARCH CEN TER
|
| An experimental and analytical study of spiral bevel gears operating in an aerospace environment has been performed. Tests were conducted within a closed loop test stand at NASA Lewis Research Center. Tests were conducted to 537 Kw (720 hp) at 14400 rpm. The effects of various operating conditions on spiral bevel gear steady state and transient temperature are presented. Also, a three-dimensional analysis of the thermal behavior was conducted using ... |
|
| Multi-Investigator Research Program (MIRP). The Science of Ultrastructural Processing |
10 OCT 95 |
|
| Authors:
L. L. Hench; FLORIDA UNIV ALACHUA ADVANCED MATERIALS RESEARCH CENTER
|
 | The goal of this program was to use chemical sol-gel processing to produce a new generation of optical, opto-electronic and bioactive materials. We have produced two new types of silica, Types V and VI silica, which are optically transparent and suitable for rapid, net shape, net surface casting of small optics, binary and surface diffraction optics, Fresnel lenses, micro- optical arrays, aspheric optics, etc. ... |
|
| Equation of State Investigations of Geologic Materials |
01 OCT 95 |
152 pages |
| Authors:
Frank W. Davies; Eric A. Smith; KTECH CORP ALBUQUERQUE NM
|
| This report documents the results of dynamic material response tests of 5 rock and 2 grouts that were performed in support of DNA's HYDROPLUS yield verification program. Pennsylvania slate, Maine slate, thawed permafrost phyllite, SHIST granite, Sierra White granite, HSG-14 grout and a granite grout were characterized in the stress range of 0.5 to 15 GPa by the derivation of Hugoniot data and by loading and release paths calculated from ... |
|
| Dynamic Response of Composite Gun Tubes Subjected to a Moving Internal Pressure |
OCT 95 |
49 pages |
| Authors:
Jerome T. Tzeng; David A. Hopkins; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| The dynamic response of a composite gun tube subjected to a moving pressure front is investigated. The flexural wave in the wall of the gun tube is modeled using both closed-form analytic and finite element methods. Results indicate that very high-amplitude and high-frequency strains are induced in the gun tube at the instant and location of projectile passage as the velocity of moving pressure front approaches the fundamental propagation velocity ... |
|
| Three-Component Velocity Measurements Downstream of a Bluff-Body Flameholder |
OCT 95 |
212 pages |
| Authors:
Charbel N. Raffoul; Abdollah S. Nejad; Richard D. Gould; WRIGHT LAB WRIGHT-PATTERSON AFB OH AERO PROPULSION AND POWER DIRECTORATE
|
| In order to enhance fuel and air mixing for more efficient combustion, it has been suggested to use bodies that generate vortical and turbulent structures in their wake. The injected fuel from the surface of in- stream mounted fuel injectors will interact with the turbulent flow and thoroughly mix with the freestream air. Simple 2-d and 3-d bluff bodies have been the subject of experimental investigations for a number of ... |
|
| Fracture Mechanics Tests and Defect Criteria for the 120-mm M121 Mortar Baseplate |
OCT 95 |
14 pages |
| Authors:
J. H. Underwood; E. Troiano; D. Crayon; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
|
| Calculations of firing stress at several locations of the 120-mm M121 mortar baseplate were made based on available strain gage data. Measurements of fracture toughness were performed for seven weld and heat-treat conditions of the 4130 steel used for the baseplate. Calculations were made of the ratio of applied K to the critical K for fracture for various combinations of firing stress and material condition. Based on the results of ... |
|
| Generalized Linear Elastic Fracture Model for Advanced Materials |
30 SEP 95 |
155 pages |
| Authors:
James G. Goree; Alex S. Selvarathinam; CLEMSON UNIV SC DEPT OF MECHANICAL ENGINEERING
|
| The branched crack problem for both an isotropic and anisotropic material is solved using the method of dislocations, and the stress intensity factors and T-stress in front of the branched crack are evaluated numerically. The T-stress based fracture criteria, developed by Cotterell and Rice for a flat crack, is modified by incorporating an experimentally determined critical T- stress value (Tcrit). Based on this Tcrit, a modified T-stress based fracture criteria ... |
|
| Acoustic Emission on Cofferdam Distress Warning System and Ancillary Acoustic Emission Monitoring; Melvin Price Locks and Dam. Phase 3 |
SEP 95 |
189 pages |
| Authors:
GROUND ENGINEERING INC ST LOUIS MO
|
| A research program was conducted to develop a cofferdam distress warning system and monitor the acoustic emissions generated by the third-phase cofferdam of the Melvin Price Lock and Dam. The purpose of this study was to extend existing understanding of acoustic emission (AE) within large sheet-pile cell stractures to the design, configaration, and operation of a cofferdam Distress Warning System (DWS) capable of automatic operation for an extended period and ... |
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| Use of Reinforcement in a Nonlinear, Incremental Structural Analysis |
SEP 95 |
76 pages |
| Authors:
Barry D. Fehl; Chris A. Merrill; ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MS
|
| This report discusses the modeling of reinforcement in a finite element method known as nonlinear, incremental structural analysis (NISA). Several simple problems are used to show how reinforcement may be included in a finite element analysis. The problems include an axially loaded beam, a simply supported beam in bending, and a fully supported slab. Closed form solutions for each of the problems are ... |
|
| LAMPAT: A Software Tool for Analyzing and Designing Thick Laminated Composite Structures |
SEP 95 |
64 pages |
| Authors:
Travis A. Bogetti; Christopher P. Hoppel; Bruce P. Burns; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| The U.S. Army Research Laboratory has recently developed an innovative analysis and design software tool for evaluating the mechanical performance of thick section laminated composite material structures. The software tool has been given the name LAMPAT and is intended to be used in conjunction with traditional finite element analysis codes. LAMPAT implements a 'smearing-unsmearing' methodology, an approach that is often employed in the structural analysis of thick multi-ply laminated composite ... |
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| Near-Wall Measurements of a Three-Dimensional Turbulent Boundary Layer |
AUG 1995 |
211 pages |
| Authors:
Debora A. Compton; John K. Eaton; STANFORD UNIV CA THERMOSCIENCES DIV
|
| In order to improve predictions of flow behavior in numerous applications there is a great need to understand the physics of three- dimensional turbulent boundary layers, dominated by near-wall behavior. To that end, an experiment was performed to measure near-wall velocity and Reynolds stress profiles in a pressure-driven three-dimensional turbulent boundary layer. The flow was achieved by placing a 30 deg wedge in a straight duct in a wind tunnel, ... |
|
| Nonlinear Geometric and Material Behavior of Composite Shells with Large Strains |
AUG 95 |
479 pages |
| Authors:
Scott A. Schimmels; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING
|
| A two-dimensional, geometrically and materially nonlinear shell theory applicable to arbitrary geometries described by orthogonal curvilinear coordinates and encompassing large displacements, moderate rotations for large strain situations has been developed. Additionally, the theory includes Jacobian transformation matrices, based upon displacement parameters, for the Cauchy - 2nd Piola-Kirchhoff stress-state and the Cauchy (Almansi) - Green strain-state transformations, and a layered material approach is included for the elastoplastic analysis to allow for ... |
|
| Nonlinear Geometric and Material Behavior of Composites with Large Strains |
AUG 95 |
476 pages |
| Authors:
Scott A. Schimmels; WRIGHT LAB WRIGHT-PATTERSON AFB OH
|
| A two-dimensional, geometrically and materially nonlinear shell theory applicable to arbitrary geometries described by orthogonal curvilinear coordinates and encompassing large displacements, moderate rotations for large strain situations has been developed. Additionally, the theory includes Jacobian transformation matrices, based upon displacement parameters, for the Cauchy - 2nd piola-Kirchhoff stress-state and the Cauchy (Almansi) - Green strain-state transformations, and a layered material approach is included for the elasto- plastic analysis to allow ... |
|
| Proceedings of the Workshop on Effects of Piles on Soil Properties Held in Vicksburg, Mississippi on 13-15 July 1993 |
AUG 95 |
333 pages |
| Authors:
John M. Anderson; William M. Myers; ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MS GEOTECHNICAL LAB
|
| The Workshop on Effects of Piles on Soil Properties was held at the U.S. Army Engineer Waterways Experiment Station on 13-l5 July 1993, and this report presents the proceedings of that workshop. The Workshop was conducted to evaluate needs for research to he conducted by the private sector, institutions of higher learning, or Government agencies concerning the changes in soil properties caused by emplacement of piles or other deep foundation ... |
|
| Bending Strength Model for Internal Spur Gear Teeth |
12 JUL 95 |
|
| Authors:
M. Savage; K. L. Rubadeux; H. H. Coe; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH LEWIS RESEARCH CEN TER
|
| Internal spur gear teeth are normally stronger than pinion teeth of the same pitch and face width since external teeth are smaller at the base. However, ring gears which are narrower, have an unequal addendum or are made of a material with a lower strength than that of the meshing pinion may be loaded more critically in bending. In this study, a model for the bending strength of an internal ... |
|
| Traction Launch of Scaled Laboratory |
JUL 95 |
36 pages |
| Authors:
Brett R. Sorensen; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| This report discusses the design, analysis, and testing phases of a modification in subscale, kinetic energy projectile technology. Typically, subscale penetrators are posh launched, while the actual full-scale penetrators are traction launched. This condition was acceptable until recently when posh launch technology could no longer fully satisfy the needs of the researcher. Therefore, a technique for implementing traction launch technology into the subscale laboratory environment was needed. This report presents ... |
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| Finite Strain Plasticity Constitutive Modeling in Computational Mechanics |
JUL 95 |
36 pages |
| Authors:
Norris J. Huffington Jr; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
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| The utility of employing discrete point input constitutive data (effective stress vs. effective plastic strain) for finite elastoplastic response problems is examined. A difficulty that occurs when the response effective plastic strain passes points of slope discontinuity in the input data is noted, and an algorithm that circumvents this difficulty is introduced. This algorithm has been successfully incorporated in the DYNA3D hydrocode and the NIKE3D structural mechanics code. (MM) ... |
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STRESS ANALYSIS
