| Thermomechanical and Fracture Analysis of Silicon Carbide in Cannon Bore Applications |
JUN 2003 |
13 pages |
| Authors:
J. H. Underwood; P. J. Cote; G. N. Vigilante; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
|
 | A 200 W/mm(2) heat flux typical of cannon bore heating is applied to a silicon carbide (SiC) sample using pulsed laser heating that simulates cannon firing. Thermomechanical models of the near-bore failure processes in fired chromium plated steel cannons are adapted to evaluate SiC for potential use in cannon bore applications. Near-bore transient temperatures are calculated using a finite-difference method and validated using the observed depth and known temperature of ... |
|
| Fatigue and Hydrogen Cracking in Cannons With Mechanical and Thermal Residual Stresses |
APR 2003 |
16 pages |
| Authors:
J. H. Underwood; A. P. Parker; E. Troiano; G. N. Vigilante; M. D. Witherell; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
|
| Bauschinger-modified autofrettage residual stresses are used to improve the fatigue intensity factor model for fatigue life of cannon pressure vessels. Effects of yield strength and initial crack size are included with applied and residual stress. In an S-N description of cannon tube life that matches full-scale cannon fatigue test results with an R2 correlation of O.92. Thermally induced residual stress near the bore of a fired cannon is modeled by ... |
|
| A Fractographic Study of a Circa AD83 Roman Nail |
MAY 2000 |
15 pages |
| Authors:
A. A. Kapusta; J. H. Underwood; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
|
| Results are presented of a scanning electron microscope fractography study of a circa ADS3 iron nail from the Roman fortress at Inchtuthil, Perthshire, Scotland. The fracture surface studied was created under embrittling conditions of low temperature, an added stress raiser, and high strain-rate loading. Fractography features are discussed in relationship to the classic cataloguing and metallographic examination of the Inchtuthil nails in earlier work by Angus, Brown, and Cleere. ... |
|
| Gray Layers and the Erosion of Chromium Plated Gun Bore Surfaces |
APR 2000 |
9 pages |
| Authors:
J. H. Underwood; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
|
| In June 1999, Dr. Cote supplied a prepublication copy of his and Mr. Rickard's report, "Gray Layers and the Erosion of Chromium Plated Gun Bore Surfaces," and requested this author's comments. These comments are offered here. |
|
| Loading Frequency and its Effects on the Fatigue Life of A723 Steel |
OCT 1999 |
12 pages |
| Authors:
E. Troiano; C. Mossey; J. H. Underwood; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET WEAPONS LAB
|
| The fatigue life of pressure vessels manufactured from two strength levels (166 Ksi and 190 Ksi) of A723 steel has been modeled, and the life predictions using the model have verified that a field loading cycle is equivalent to a laboratory pressurization loading cycle. One key assumption in the model is that a minimum crack initiator must be present in order to attain aone-to-one correlation. If the minimum crack initiator ... |
|
| Thermochemical Model of Hydrogen Cracking at Heat-Affected Cannon Bore Surfaces |
AUG 1999 |
20 pages |
| Authors:
J. H. Underwood; G. N. Vigilante; E. Troiano; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
|
| Two examples of hydrogen cracking in the heat-affected region of fired cannons are given, including metallographic evidence of damage at various depths near the bore surface. The depth of steel transformation due to firing is used to verify near-bore temperature distributions and transient and residual stress distributions calculated using classic one-dimensional heat flow analysis. Predicted depths of thermal damage and hydrogen cracks compare well with observed depths for different crack ... |
|
| Analysis of a Piston Experiencing Environmentally-Assisted Cracking as aResult of Compressive Overloading |
JUN 1999 |
17 pages |
| Authors:
E. Troiano; G. N. Vigilante; J. H. Underwood; C. Mossey; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY CLOSE COMBAT ARMAMENTS CENTER
|
| A piston used in service in a closed-ended pressure vessel, as a component of the seal for the vessel, cracked after as few as two high-pressure loading cycles. As a further complication, the finite element analysis was predicting compression on the cracked piston face during the loading cycle. The cracks in the piston emanated in a radial fashion and were measured at 1.5-mm deep. Upon subsequent loading, the cracks grew ... |
|
| Hydrogen Cracking During Service of High Strength Steel Cannon Components |
SEP 97 |
27 pages |
| Authors:
J. H. Underwood; E. Troiano; G. N. Vigilante; A. A. Kapusta; S. Tauscher; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET WEAPONS LAB
|
| An investigation of environmental cracking during service of high strength steel cannon components is described. Two cases of cracking occurred in similar prototypes of an advanced cannon over a two-year period. The materials, components configurations, applied and residual stresses, environmental conditions, and the resulting cracking behaviors and SEM fracture surface characteristics are outlined. Laboratory hydrogen cracking tests of the cannon materials, finite element stress analysis, and stress intensity factor calculations ... |
|
| Modification of ASTM Standard E1681 on Environmental Cracking to Include Bolt-Load Specimen Testing |
JUL 1997 |
36 pages |
| Authors:
J. H. Underwood; W. A. VanDerSluys; G. N. Vigilante; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
|
| Benet Laboratories experience with environmental cracking of cannon components has been combined with the technical expertise of various participants at ASTM technical meetings and symposia to develop a modification to ASTM Standard E1681. 'Test Method for Determining a Threshold Stress Intensity Factor for Environment Assisted Cracking of Metallic Materials Under Constant Load.' A bolt-loaded compact specimen has been added to the standard to allow constant displacement bolt-load tests of environmental ... |
|
| Hydrogen-Induced Cracking Tests of High-Strength Steels and Nickel-Iron Base Alloys Using the Bolt-Loaded Specimen |
MAR 97 |
27 pages |
| Authors:
G. N. Vigilante; J. H. Underwood; D. Crayon; S. Tauscher; T. Sage; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
|
| Hydrogen-induced cracking tests were conducted on high strength steels and nickel-iron base alloys using the constant displacement bolt-loaded compact specimen. The bolt-loaded specimen was subjected to both acid and electrochemical cell environments to produce hydrogen. The materials tested were A723. Maraging 200, PH 13-8 Mo. Alloy 718, Alloy 706, and A286, ranging in yield strength from 760-1400 MPa. The effects of chemical composition, refinement, heat treatment, and strength on hydrogen-induced ... |
|
| Ambient Temperature Testing of Metallic Materials Exposed to Propellant Combustion Environments Containing Hydrogen |
MAR 97 |
11 pages |
| Authors:
G. N. Vigilante; P. J. Cote; J. H. Underwood; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
|
| Combustion gases containing hydrogen can cause severe environmental degradation and cracking in the high strength steels used in gun tubes. Although the hydrogen is evolved at the elevated temperatures of combustion, the deleterious effects of hydrogen on steel are most severe near ambient temperature. |
|
| Some Methods of Representing Fatigue Lifetime as a Function of Stress Range and Initial Crack Size |
DEC 96 |
22 pages |
| Authors:
A. P. Parker; J. H. Underwood; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
|
| An analysis is developed which permits fatigue lifetimes of components with pre-existing crack-like defects to be represented by a single expression which is a function of stress range and initial defect size; this is designated the Fatigue Intensity Factor (FIF). A graphical representation indicates that all such failures will fall upon a single, flat surface. The conventional S-N curve is shown to be a special case of this surface. Outliers ... |
|
| Fatigue Life Assessment of Steel Pressure Vessels with Varying Stress Concentration, Residual Stress, and Initial Cracks |
JUL 96 |
23 pages |
| Authors:
J. H. Underwood; A. P. Parker; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
|
| A single-parameter representation of local stress range, initial crack size, and material yield strength is proposed for describing the intensity of the fatigue loading of a structural component. A logarithmic plot of single- parameter fatigue life results provides a single straight-line description of fatigue life behavior over a broad range of material, configuration, and loading conditions. Expressions for calculating the local stress range at the failure site are outlined, including ... |
|
| 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 ... |
|
| Low Cycle Notched Fatigue Behavior and Life Predictions of A723 High Strength Steels |
APR 95 |
26 pages |
| Authors:
E. Troiano; J. H. Underwood; D. Crayon; R. T. Abbott; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
|
| Two types of ASTM A723 steels have been investigated for their low cycle fatigue behavior (less than 104 cycles to failure). Specimens were tested in four-point bending, both with and without notches, and the measured fatigue lives were compared with those predicted by Neuber notch analysis (classic and elastic/plastic remote applied loading), and standard fracture mechanics life prediction techniques. Comparison of measured and predicted lives indicates that the elastic/plastic Neuber ... |
|
| Fracture Testing of Metals and Composites: Tests and Analyses for Failure Problems with Armament Components |
MAR 95 |
29 pages |
| Authors:
J. H. Underwood; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY CLOSE COMBAT ARMAMENTS CENTER
|
| Fracture tests have been broadly applied to failure of armament, including failures caused by each of the three general types of fracture--fast fracture, fatigue cracking, and environmentally assisted cracking. This report describes some fracture mechanics tests and related analyses that have been useful to characterize fracture in armament components made from high strength steels and carbon/epoxy laminates. These include J integral fracture toughness, notch fatigue life, and environmentally-assisted cracking tests ... |
|
| Residual Stress Effects at a Notch Root in A723 Steel to Extend Fatigue Life |
FEB 95 |
22 pages |
| Authors:
J. H. Underwood; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
|
| Fatigue life tests were performed with notched bend specimens of ASTM A723 steel with three types of residual stress treatments and resulting residual stress: shot peening, bole swaging, and tensile overload. The three treatments produced widely different depths and surface values of residual stress near the notch root and different fatigue lives depending mainly on the notch root surface value of compressive residual stress. The highest life was measured from ... |
|
| Fatigue Life and Fracture Analyses for the M185/M284 Breech Ring |
JAN 95 |
21 pages |
| Authors:
J. H. Underwood; E. Troiano; A. A. Kapusta; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
|
| Fracture mechanics and fatigue life analyses were performed for Ml85/ M2S4 breech rings, with emphasis on ring Serial No. 1659, which failed during safe life testing after 109 pressure cycles. Mechanical and fracture properties from the breech rings were measured and used to perform yield-before-break fracture analysis. Scanning electron fractography was used to determine the size of defect present in ring Serial No. 1659 prior to laboratory testing and the ... |
|
| Stress Concentration, Stress Intensity, and Fatigue Crack Growth Along Evacuators of Pressurized, Autofrettaged Tubes |
DEC 94 |
30 pages |
| Authors:
A. P. Parker; J. H. Underwood; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
|
| A stress analysis has been conducted on a pressurized, fully or partially autofrettaged cylinder with a small diameter evacuator hole penetrating radially through the wall. Pressure was applied on the inside diameter (ID) of the tube, and all or part of this pressure was applied on the evacuator hole surfaces. Total hoop stress concentrations have been determined for a range of radial locations along the evacuator and stress intensity factors ... |
|
| Report of Visiting Scientist Attachment of Dr. Anthony P. Parker of University of Northumbria, U.K. to Benet Laboratories, July - August 1993 |
DEC 94 |
16 pages |
| Authors:
J. H. Underwood; A. P. Parker; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
|
| The results of a two-month visiting scientist attachment of Dr. Anthony P. Parker from the University of Northumbria at Newcastle, United Kingdom to the U.S. Army Armament Research, Development, and Engineering Center, Benet laboratories are reported. A description is given of the arrangements for the visit, the technical topics addressed during the visit, and the status of the technical reports that give details of the results of the visit. ... |
|
| Fatigue Life Analysis and Tests for Thick-Walled Cyclinders Including Effects of Overstrain and Axial Grooves |
SEP 94 |
24 pages |
| Authors:
J. H. Underwood; A. P. Parker; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
|
| A fracture mechanics-based fatigue life analysis was developed for pressurized thick-walled cylinders autofrettaged by overstrain and with one or several semi-elliptical-shaped axial grooves at the inner diameter. The fatigue life for a crack initiating at the root of the groove was calculated for various cylinder, groove, and crack configurations and for different material yielding condition. Comparisons were made with fatigue crack growth and laboratory life results from A723 thick-walled cylinders ... |
|
| Notch-Tip Damage and Translaminar Fracture Toughness Measurements from Carbon/Epoxy Laminates |
MAR 94 |
19 pages |
| Authors:
J. H. Underwood; M. T. Kortschot; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
|
| Notched (0/+45/90/-45) carbon/epoxy laminates were used to study translaminar fracture, where through-thickness cracking propagates across fibers and laminae. Radiographs of damage were compared with crack growth determined from load-versus-deflection plots using elastic fracture mechanics. Comparison of damage at the notch tip with fracture mechanics evaluation identified some material/test conditions for which a critical value of fracture toughness is a useful concept. For other condition the extent of damage in the ... |
|
| Simpler J sub IC Test and Data Analysis Procedures for High Strength Steels |
JAN 94 |
27 pages |
| Authors:
J. H. Underwood; E. J. Troiano; R. T. Abbott; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
|
| Tests of five medium and high strength steels were used to investigate some prospective simplification in J sub Ic test and data analysis procedures. Three-point bend specimens with materials strength of 500 to 1500 MPa and nominal thickness of 10 mm were tested at room temperature. The investigation (1) J sub Ic test using measured crack-mouth displacement to calculate load-line displacement based on an expression that relates the two displacements; ... |
|
| Crack Arrest Fracture Toughness Measurement of a Quenched and Tempered Ship Plate Steel |
DEC 92 |
|
| Authors:
I. A. Burch; J. H. Underwood; MATERIALS RESEARCH LABS ASCOT VALE (AUSTRALIA)
|
 | A quenched and tempered HSLA type ship plate steel was used to investigate the influence of dynamic effects on crack propagation and arrest behaviour and to measure the static arrest toughness, KIA. The specimen type used was a wedge-loaded modified compact tension specimen which provides fixed grip conditions during crack extension. Under fixed grip conditions no external work is performed on the specimen after crack initiation and only elastic strain ... |
|
| Degradation and Failure Modes of Carbon/Bismaleimide Laminates Subjected to a Tropical Exposure |
AUG 92 |
17 pages |
| Authors:
J. H. Underwood; A. A. Kapusta; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
|
| A scanning electron microscope (SEM) was used to characterize the degradation of the outermost layers of carbon/bismaleimide laminates as the result of exposure to a natural tropical environment. The surface that was exposed to the sun for 4000 hours suffered complete degradation of the bismaleimide matrix to a shallow depth. SEM fractography showed little difference in the appearance of the fibers in a carbon/bismaleimide laminate, which displayed considerable fiber pullout ... |
|
| Environmentally-Controlled Fracture of an Overstrained A723 Steel Thick- Walled Cylinder |
AUG 92 |
32 pages |
| Authors:
J. H. Underwood; V. J. Olmstead; J. C. Askew; A. A. Kapusta; G. A. Young; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
|
| A through-wall, 1.7-m long crack grew suddenly from a notch in a 285- mm outer diameter (OD) of an A723 steel overstrained tube that was undergoing plating operations with no externally applied loads. The fracture mechanics tests and analyses and the fractography performed to characterize the cracking are described in this report. The tube had a yield strength of 1200 MPa, fracture toughness of 150 MPavm, and a tensile residual ... |
|
| Correlation between Fracture Toughness, Charpy V-Notch Impact Energy, and Yield Strength for ASTM A723 Steel |
MAR 92 |
14 pages |
| Authors:
J. A. Kapp; J. H. Underwood; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
|
| A large quantity of data for ASTM A723 steel correlating yield strength, Charpy impact energy, and fracture toughness has been compared with the Rolfe-Novak-Barsom correlation. The general conclusion is that this correlation is conservative, because if we estimate fracture toughness from Charpy impact energy measurements, the estimated toughness is less than the measured value. The data may be somewhat questionable, however, because the fracture toughness and Charpy impact energy measurements ... |
|
| Correlation Between Fracture Toughness, Charpy V-Notch Impact Energy, and Yield Strength for ASTM A723 Steel |
92 |
|
| Authors:
J. A. Kapp; J. H. Underwood; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY CLOSE COMBAT ARMAMENTS CENTER
|
|
| Environmentally-Controlled Fracture of an Overstrained A723 Steel Thick- Walled Cylinder |
92 |
|
| Authors:
J. H. Underwood; V. J. Olmstead; J. C. Askew; A. A. Kapusta; G. A. Young
|
|
| Crack Arrest and Static Fracture Toughness Tests of a Ship Plate Steel |
DEC 91 |
32 pages |
| Authors:
J. H. Underwood; I. A. Burch; J. C. Ritter; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
|
| The recently standardized ASTM crack arrest fracture toughness test method was modified for use with an Australian low alloy, 700 MPa strength, quenched and tempered steel used for ship plate. Specimens 50-mm thick in longitudinal and transverse orientations were tested at -60 C with various depths of side groove. Specimen configurations somewhat outside the range of the ASTM method were found to be useful for this steel and were suggested ... |
|
| Fracture Toughness Tests and Displacement and Crack Stability Analyses of Round Bar Bend Specimens of Liquid-Phase Sintered Tungsten |
OCT 91 |
24 pages |
| Authors:
J. H. Underwood; F. I. Baratta; J. J. Zalinka; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
|
| Plane strain fracture toughness tests were performed using the recently proposed round bar bend test procedure with a liquid-phase sintered tungsten alloy. The tests included a direct comparison of fracture toughness from rectangular and round bend specimens and measurements of load line compliance using the unloading technique of J integral fracture tests. Complementary displacement and crack growth stability analyses of the round bar were performed as an extension of recent ... |
|
| Effects of Notch Geometry and Moisture on Fracture Strength of Carbon/ Epoxy and Carbon/Bismaleimide Laminates |
DEC 90 |
45 pages |
| Authors:
J. H. Underwood; I. A. Burch; S. Bandyopadhyay; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET WEAPONS LAB
|
| Cross-ply panels of various ply orientations and 1 to 2-mm thickness were tested in tension with a center notch to determine the translaminar fracture toughness and in bending with no notch to determine the bulk flexural strength and modulus. Carbon/epoxy panels with a variety of notch lengths and widths were subjected to laboratory air conditions before testing. Carbon/ bismaleimide panels with one basic notch configuration were tested in three pretest ... |
|
| Review of ASTM Symposium on Surface Crack Growth: Models, Experiments, and Structures |
NOV 90 |
21 pages |
| Authors:
W. G. Reuter; J. H. Underwood; J. C. Newman; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
|
| An overview of the ASTM Symposium on Surface Cracks: Models, Experiments, and Structures, held on 25 April 1988 in Sparks, Nevada, is presented. The background and objective for the symposium are described and the technical papers presented and published in the proceedings are summarized. The papers are in two general categories: (a) results of analytical models and experiments of surface-cracked specimens and components subjected to monotonic loading, and (b) experiments ... |
|
| Load-Line Displacements for Three-Point Bend J Tests Using Bottom Surface Displacements |
OCT 90 |
14 pages |
| Authors:
J. H. Underwood; M. D. Witherell; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
|
| Finite element calculations show that elastic displacements along the bottom surface of a three-point bend speciment can be used to obtain a close approximation to the load-line displacement at the crack line. The use of load- line displacement for measuring crack growth by unloading compliance is discussed with application to a simplified test procedure for J-integral fracture toughness tests. Keywords: Load line displacement, Three point bend, Finite element. (JS) ... |
|
| Fracture Toughness and Fatigue Crack Initiation Tests of Welded Precipitation-Hardening Stainless Steel |
JAN 90 |
36 pages |
| Authors:
J. H. Underwood; R. A. Farrara; G. P. O'Hara; J. J. Zalinka; J. R. Senick; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
|
| An analysis of a welded stainless steel box beam that experienced a structural failure during fatigue testing is described. Cracks initiated at notches caused by partial penetration welds and grew to a length of several centimeters in about 100 load cycles. The objective of this report is to describe the characterization of fracture toughness and fatigue crack initiation for the precipitation-hardening stainless steels used for the welds and parent plate ... |
|
| Applications and Limitations of Finite Element Analysis to Armament Components |
JUL 89 |
29 pages |
| Authors:
J. H. Underwood; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
|
| A review of three applications of finite element methods for stress, displacement, and stress intensity factor analyses of various armament component is presented. First, stress analysis of sections from outside diameter notched cylinders was performed to describe the cylinder's fatigue life behavior. Second, stress analysis methods for long rod projectiles subjected to inertial loading were developed; the stresses at a failure location of a projectile were used to help explain ... |
|
| Fracture and Three Dimensional Stress Analyses of 7075 Aluminum Projectile Components Under Spin and Inertia Load |
JUN 89 |
27 pages |
| Authors:
J. H. Underwood; M. A. Scavullo; G. P. O'Hara; B. A. Konrad; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
|
| A fracture case study of a high strength aluminum projectile component subjected to inertial and spin loading during launch from a cannon is presented. A three-dimensional finite element model was used to calculate the projectile stresses and to determine which of the several types of loading was the primary cause of failure. A design change to minimize spin loading resulted in a significantly reduced failure incidence. Mechanical and fracture mechanics ... |
|
| Analysis of Some Fracture Mechanics Test Procedures for Defence Research Applications |
APR 89 |
|
| Authors:
J. H. Underwood; I. A. Burch; M. Z. Shah Khan; MATERIALS RESEARCH LABS ASCOT VALE (AUSTRALIA)
|
| Analysis has been presented of six fracture mechanics specimens and associated test procedures. Stress intensity factor results, and displacement results in some cases, have been compared for each specimen with numerical results and limit solutions from the literature. The specimens and test procedures analyzed are a compact specimen for general fracture testing; a crack arrest compact specimen, a modified compact specimen for brittle coating tests, a bend specimen for stress-corrosion ... |
|
| Overview of ASTM Symposium on Analytical and Experimental Methods for Residual Stress Effects in Fatigue |
FEB 89 |
15 pages |
| Authors:
R. L. Champoux; J. H. Underwood; J. A. Kapp; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
|
| An overview of the ASTM Symposium on Analytical and Experimental Methods for Residual Stress Effects in Fatigue, held on 20-21 October 1986 in Phoenix, Arizona, is presented. The background and objective for the symposium are described and the technical papers presented at the symposium and published in the proceedings are summarized. The papers are in two general categories: (1) Effects of residual stress near the surface of a specimen or ... |
|
| Analytical and Experimental Methods for Residual Stress Effects in Fatigue |
NOV 88 |
|
| Authors:
R. L. Champoux; J. H. Underwood; J. A. Kapp; AMERICAN SOCIETY FOR TESTING AND MATERIALS PHILADELPHIA PA
|
| Separate records are available on three papers from this symposium; see MCIC-138457 to MCIC-138459. |
|
| Microscopic Aspects of Failure and Fracture in Cross-Ply Fiber- Reinforced Composite Laminates |
NOV 88 |
28 pages |
| Authors:
S. Bandyopadhyay; E. P. Gellert; V. M. Silva; J. H. Underwood; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET WEAPONS LAB
|
| Tensile fracture and interlaminar mode I delamination failure may be considered as the upper and lower bounds of performance for fracture of fiber composite laminates. While these failures have been studied extensively in the literature, little progress has been made towards developing an understanding of the micromechanisms of the failure processes which, in fact, govern the macroscopic performance. Tensile fracture, Interlaminar fracture, Fracture surface, Carbon epoxy, Fracture toughness, Carbon bismaleimide, ... |
|
| Stress-Corrosion Cracking of Liquid-Phase Sintered Tungsten Alloys |
OCT 88 |
35 pages |
| Authors:
M. Z. Khan; J. H. Underwood; I. A. Burch; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET WEAPONS LAB
|
| This study addresses the stress-corrosion cracking susceptibility of liquid-phase sintered tungsten alloys during long-term storage. These alloys are used for kinetic energy penetrators in military applications and it is essential that the structural integrity of the penetrator is not diminished due to the combined action of the chemical environment and the residual manufacturing stresses. Stress-corrosion cracking, Liquid-phase tungsten, Unloading compliance, Kinetic energy penetration, Fracture mechanics, Crack closure. (JES) |
|
| Proposed Standard Arc-Bend Chord-Support Fracture Toughness Specimens and K Expressions |
AUG 88 |
25 pages |
| Authors:
J. H. Underwood; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
|
| Collocation and finite element calculations and limit solutions were used to propose standard geometries and K expressions for measuring fracture toughness with arc-bend chord-support specimens. Polynomial expressions for K were determined for a wide range of crack length and for two span-to-depth ratios. Fracture toughness of steel and aluminum alloys was measured using the proposed methods and compared with results from existing standard methods. |
|
| Comparison of Compliance Results for the Wedge-Loaded Compact Specimen |
JUL 88 |
15 pages |
| Authors:
J. H. Underwood; J. C. Newman Jr; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER DOVER NJ CLOSE CO MBAT ARMAMENTS CENTER
|
| Results of the ratio of stress intensity factor to crack mouth displacement as a function of crack length are presented for the wedge-loaded compact specimen. Comparisons are made between experimental compliance results, numerical results from collocation methods, and deep crack limit solution results. Applications are for crack arrest and stress corrosion cracking tests for metals and other materials under predominantly linear elastic conditions. |
|
| Wide Range Stress Intensity Factor Expression for an Edge-Cracked Round Bar Bend Specimen |
MAY 88 |
20 pages |
| Authors:
J. H. Underwood; R. L. Woodward; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
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| An edge-cracked round bar was analyzed for use as a fracture mechanics test specimen. Shallow and deep crack limit solutions were developed and combined with experimental and numerical results to obtain K expressions which apply for all crack depths. Specimen and loading geometries were suggested for standardized fracture mechanics tests using a round bar. Keywords: Fracture testing, Limit solution, Bend specimen, Cylindrical geometry, Cracks. (JES) |
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| Additional Fracture and Strength Test Results for A723 Steel and 38644 Titanium |
APR 1988 |
20 pages |
| Authors:
J. H. Underwood; M. H. Kamdar; R. R. Fujczak; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
|
| Four types of additional mechanical test results are described for high strength steel and titanium alloys, as a continuation of previous work. 1) The effects of elevated temperature on the circumferential orientation tensile properties of titanium and steel cylinders are described. 2) A comparison is presented of strength and fracture toughness results from two titanium ingots. 3) The fatigue lives of notched bend specimens of titanium are measured and compared ... |
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| Fracture and Fatigue |
APR 88 |
77 pages |
| Authors:
R. O. Ritchie; W. W. Gerberich; J. H. Underwood; ARMY ARMAMENT RESEARCH, DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENE T WEAPONS LAB
|
| In the last twenty years, much progress has been made with the continuum mechanics characterization of crack growth rates through the application of linear elastic and elastic-plastic fracture mechanics, and such analyses are now in widespread use for defect-tolerant design codes. Similarly, an understanding of the role of microstructure in improving the resistance to fracture and fatigue has emerged to the point where alloy design guidelines exist for the production ... |
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| A Technique for Measuring Area under a Curve |
MAR 88 |
|
| Authors:
J. H. Underwood; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
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| Measurement of the area under a curve is often the most direct way to determine the energy of a mechanical system. Area measurements are now routinely used in fracture mechanics testing as part of the standard test method for the J-integral fracture toughness. Vossoughi recently described a method for measuring the area under a curve, based on the weight of a template of the area. The technique suggested here is ... |
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| Elastic, Strength, and Stress Relaxation Properties of A723 Steel and 38644 Titanium for Pressure Vessel Applications |
MAR 1988 |
34 pages |
| Authors:
J. H. Underwood; R. R. Fujczak; R. G. Hasenbein; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET WEAPONS LAB
|
| Mechanical properties of a high strength steel and a titanium alloy have been measured for application to compound cylinders of steel and titanium subjected to elevated temperature. Results are presented from tests and analyses of elastic and failure strength, stress relaxation, fracture toughness, and microstructure and microhardness. Conclusions are drawn regarding the suitability of the two materials when subjected to conditions typical of cannon fabrication processes and service loading. Keywords: ... |
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| Stress Corrosion Cracking of A723 Steel Pressure Vessels: Two Case Studies |
JAN 88 |
40 pages |
| Authors:
J. H. Underwood; J. J. Miller; ARMY ARMAMENT RESEARCH, DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENE T WEAPONS LAB
|
| Two separate investigations of apparent stress corrosion cracking of cannon tubes under field service conditions are described. The first investigation involved several tubes in which cracking initiated at the inner diameter surface due to the combination of cannon firing products and tensile residual stresses. Results of metallographic and fracture surface studies; residual stress measurements; fatigue life and material mechanical tests; and stress corrosion simulation tests of tube sections are presented ... |
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