Additional microyield measurements on HIP-50 beryllium samples, subjected to a variety of selected heat treatments, were performed. It was determined that of the several treatments that were employed the most significant increase in the value of the microyield strength occurred from a 100 hour exposure to 600 C. A microyield value of about 26.5 klb/sq in. was measured after this treatment compared to an as-received value of 17.2 klb/sq in. Examination of the microyield data plotted on...
Topics: DTIC Archive, Kumar,K, CHARLES STARK DRAPER LAB INC CAMBRIDGE MA, *THERMAL STABILITY, *GYROSCOPES,...
Stress and strain profiles have been recorded in targets impacted by long-rod kinetic-energy projectiles. Stress gauge records were strongly influenced by the strain field in the target, so compensating strain measurements were used to derive the correct stress profile. Strain-compensated stress gauges in the projectile path measured stress which increased to a value that remained nearly constant until penetration neared the gauge. This constant stress was close to the value of the Hugoniot...
Topics: DTIC Archive, Pritchard, Dennis S, ARMY BALLISTIC RESEARCH LAB ABERDEEN PROVING GROUND MD, *KINETIC...
Chemical crosslinking of polymeric binders is possibly the most significantly factor affecting the mechanical behavior of unfilled and highly filled elastomers. There are basically two physical methods used by various investigators for experimentally determining the degree of crosslinking swelling method using Flory's equation and the equilibrium stree-strain method. The procedure dicussed inthis report is recommended as a tentative standard procedure to be followed in the collection of...
Topics: DTIC Archive, Martin, Donald L , Jr, ARMY MISSILE RESEARCH DEVELOPMENT AND ENGINEERING LAB REDSTONE...
A simple method is presented for estimating the combined influence of strain-hardening and strain-rate sensitivity on the permanent deformation of rigid-plastic structures loaded dynamically. A study is made of the particular case of a beam supported at the ends by immovable frictionless pins and loaded with a uniform impulse. The results of this work indicates that considering strain-hardening alone when appropriate or strain-rate sensitivity alone gives permanent deformations which are...
Topics: DTIC Archive, Jones, Norman, BROWN UNIV PROVIDENCE RI DIV OF ENGINEERING, *BEAMS(STRUCTURAL),...
Theoretical expressions for bending moment versus depth of elastic- plastic interface for both rectangular, tubular, and solid circular beams are developed. Theoretical expressions for strain as a function of geometry and depth of elastic-plastic interface for each type of cross section are derived. The possibility of a strain singularity occurring as the elastic-plastic interface approaches the neutral axis is pointed out. The assumption that 'planes remain plane' is examined. Experimental...
Topics: DTIC Archive, Milligan, R V, ARMY ARMAMENT RESEARCH AND DEVELOPMENT CENTER WATERVLIET NY LARGE...
Special numerical techniques are described which permit productive utilization of digital filters in the analysis of ballistic data. Specific examples are given which demonstrate the use of these techniques. In the analysis of ballistic data such as pressure, strain, and acceleration, and the Fourier spectrum is an extremely useful tool. For nonreal-time data analysis, various numerical manipulations can be performed to enhance the applicability of Fourier techniques. These manipulations...
Topics: DTIC Archive, Walbert, James N, ARMY BALLISTIC RESEARCH LAB ABERDEEN PROVING GROUND MD,...
The behavior of materials under mechanical stress can be divided into three distinct regimes: (1) linear elastic response up to the elastic limit, (2) inelastic behavior beyond the elastic limit and up to that loading at which first failure occurs locally, and (3) subsequent crack propagation and total composite failure. The crack initiation and its subsequent propagation, described above as the third regime, is the subject of the present study. A method has been developed for predicting the...
Topics: DTIC Archive, Adams, Donald F., RAND CORP SANTA MONICA CA, *FIBER REINFORCED COMPOSITES, *CRACK...
The complete absence of a corrosive atmosphere during the deformation of aluminum leads to a postponement of the formation of slip bands in which fatigue cracks are known to initiate. This phenomenon can be explained on the basis of a lack of dislocation pinning at the surface due to oxidation processes. Surface anodic layers suppress surface slip in proportion to their thickness. Although slip may not be observed on the top of thick anodic layers, some slip can still occur at the metal-oxide...
Topics: DTIC Archive, MIDWEST RESEARCH INST KANSAS CITY MO, *FILMS, *FRACTURE(MECHANICS), *GOLD, *ALUMINUM,...
This thesis is the first in a series that is attempting to discover the mechanism by which the fracture toughness J sub 1C, of HY-series steel decreases with increasing prestrain at room temperature. This decrease J sub 1C is a function of yield strength and plane strain fracture strain. However, this reduction in J sub 1C is shown to be caused by a reduction in the plane strain fracture strain. Fractographic examinations have verified this reduction in the fracture strain and also have shown...
Topics: DTIC Archive, Mullican,James Neal, *STRAIN(MECHANICS), *STEEL, *FRACTURE(MECHANICS), STRESS STRAIN...
A cyclic strain approach to pore pressure buildup and liquefaction during earthquakes of saturated choesionless soils has been proposed and developed. One of the key findings has been the existence, for every potentially liquefiable site and sand layer, of a 'threshold ground surface acceleration,' a sub t, below which there is no pore pressure buildup. The value of a sub t is mainly a function of two soil parameters: the 'threshold shear strain' of the sand, gamma sub t, and its maximum shear...
Topics: DTIC Archive, Dyvik,R, RENSSELAER POLYTECHNIC INST TROY NY DEPT OF CIVIL ENGINEERING, *SAND,...
A prototype Minispar sensor system housing was attached to a simulated grate section and towed at various angles of attack and speeds in a towing basin. This was done to aid JHU/APL in evaluating the attachment hardware for structural strength. Measurements of strains at various locations on the attachment hardware were made along with bolt torques and the forward to aft pressure differential on the model. The hydrodynamically induced strains were less than 400 microstrains. Bolt torque induced...
Topics: DTIC Archive, Wisler, B B, DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP HYDROMECHANICS DEPT,...
Stress and strain profiles have been recorded in targets impacted by long-rod kinetic-energy projectiles. Stress gauge records were strongly influenced by the strain field in the target, so compensating strain measurements were used to derive the correct stress profile. Strain-compensated stress gauges in the projectile path measured stress which increased to a value that remained nearly constant until penetration neared the gauge. This constant stress was close to the value of the Hugoniot...
Topics: DTIC Archive, Pritchard, Dennis S, ARMY BALLISTIC RESEARCH LAB ABERDEEN PROVING GROUND MD, *KINETIC...
Inaccuracies in using the off-axis tension test are caused by the nonuniform stresses produced by the end constraints. The purpose of this thesis is to show that these nonuniformities can be virtually eliminated by adjusting the amount of tab clamping and selectively locating the point about which the clamp may rotate. A second phase of the study is to conduct a limited verification of a strain energy failure criteria that can account for the material nonlinearity found in composite materials....
Topics: DTIC Archive, Cron,Steven M, AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING,...
Equilibrium fields with discontinuous displacement gradients can occur in finite elasticity for certain materials. The presence of such 'equilibrium shocks' affects the energy balance in the elastostatic field, and the present paper is concerned with a notion of dissipation associated with this energy balance. A dissipation inequality is proposed for three-dimensional equilibrium shocks for both compressible and incompressible materials. The consequences of this inequality are studied for weak...
Topics: DTIC Archive, Knowles,James K, CALIFORNIA INST OF TECH PASADENA DIV OF ENGINEERING AND APPLIED...
A theory is formulated for the small-amplitude free vibration of thick, circular cylindrical shells laminated of bimodulus composite materials, which have different elastic properties depending upon whether the fiber-direction strain is tensile or compressive. The theory used is the dynamic, shear deformable (moderately thick shell) analog of the Sanders best first approximation thin-shell theory. By means of tracers, the analysis can be reduced to various simpler shell theories, namely Love's...
Topics: DTIC Archive, Bert,Charles W, OKLAHOMA UNIV NORMAN SCHOOL OF AEROSPACE MECHANICAL AND NUCLEAR...
This study evaluated magnetomechanical acoustic emission (MAE) in iron, nickel, steels and an iron-nickel alloy. The intensity of MAE increased with an increasing level of magnetization at 60 Hz and was also dependent on chemical composition, microstructure, applied stress, and prior cold work. Nickel was the highest emitter and the iron-31% nickel alloy was the lowest. Martensitic transformation and cold-working reduced MAE. Applied stress also suppressed MAE, although some enhancements were...
Topics: DTIC Archive, Ono,Kanju, CALIFORNIA UNIV LOS ANGELES DEPT OF MATERIALS, *STRAIN(MECHANICS),...
Homogeneously oxidized iron surfaces show modulated microwave reflections under strain. The effects are too small to account for the modulation found from actual vibrating systems, but are large compared to the response expected from clean metal surfaces. Tunneling junctions of Fe-Oxide-Fe have been investigated as a possible origin of the observed enhancement of strain sensitivity. Such tunneling junctions have been found to exist, at room temperature, but the effect found in model MOM...
Topics: DTIC Archive, Juretschke,Hellmut J, POLYTECHNIC INST OF NEW YORK BROOKLYN MICROWAVE RESEARCH INST,...
An examination of film recordings of strain noise, pressure fluctuations inside and outside of the strain vault, and wind velocity at WMO suggests that the long-period (LP) noise observed on the strain traces is caused by wind-pressure fluctuations that are coupled more strongly through the ground or by compression of the vault structure than through leakage of air through the vault enclosure. A study of the detection capability of the WMO LP strain seismographs shows that the environmental...
Topics: DTIC Archive, Shopland, Robert C, GEOTECH GARLAND TX, *SEISMOLOGICAL STATIONS, *UNDERGROUND...
A numerical method is described by which theoretical formulas governing the propagation of symmetric and antisymmetric waves in elastic plate theory may be evaluated. Vital to evaluating the formulas is the availability of a means for solving transcendental equations. A generalized iterative rootfinder that was developed for this purpose is described. This rootfinder provides the investigator having access to computing facilities with a reliable means for solving transcendental equations....
Topics: DTIC Archive, Ruggiero,C M, NAVAL RESEARCH LAB WASHINGTON DC, *ELASTIC PROPERTIES, *WAVE...
The application of holographic interferometry to displacement and strain determination has been reviewed. A brief introduction to the theoretical basis of holography and holographic interferometry, and a summary of recent developments is given. It is concluded that with continued development, holographic interferometry has the potential to become a routine tool for whole field displacement and strain measurement, and non-destructive testing of aircraft structures.
Topics: DTIC Archive, Rumble,S J, AERONAUTICAL RESEARCH LABS MELBOURNE (AUSTRALIA), *STRAIN(MECHANICS),...
A mathematical model of fatigue crack nucleation is described using the irreversible thermodynamics to quantify the damage caused by plastic straining. The model is based on the hypothesis that the entropy gain which results from dynamic irreversible plastic straining is a material constant. A random model of internal friction is used to calculate the irreversible part of the hysteresis energy dissipation rate, enabling the quantification of uncertainty through the variance of the dynamic...
Topics: DTIC Archive, Whaley,P W, NEBRASKA UNIV LINCOLN COLL OF ENGINEERING AND TECHNOLOGY,...
A program has been underway at the National Bureau of Standards since October 1977 to measure and understand the microcreep of materials used in gyroscopes so that dimensional instability can be improved. A methodology for microcreep testing has been developed and is described herein. Tensile microcreep test results between room temperature and 62 C on I-400 beryllium indicate that the microcreep strain does not exceed 1/100,000 in three months for applied stresses up to 20,000 psi. The...
Topics: DTIC Archive, Christ,Bruce W, NATIONAL BUREAU OF STANDARDS WASHINGTON DC, *Mechanical properties,...
There are a limited number of nondestructive evaluation techniques available for field inspection of large composite structures and practically no viable techniques for in-service inspection. With this in mind, an innovative Damage Assessment System is proposed which is based on a concept of using an optical fiber mesh, implanted into the body of a fiber reinforced composite structure. Such a mesh would become an integral part of the structure during the course of its fabrication. The selection...
Topics: DTIC Archive, Crane,Roger M, DAVID W TAYLOR NAVAL SHIP RESEARCH AND DEVELOPMENT CENTER ANNAPOLIS MD...
Measurement of the influence of water vapor in the environment on fatigue crack tip strains and stresses has been the objective of this program. In low-carbon steel, stresses in the plastic zone were deduced by imaging subcells formed during fatigue crack growth. Water vapor was found to lower the stress levels and decrease the size of the zone of stresses exceeding the yield value. Strains within the plastic zone and at the crack tip may be determined by the stereoimaging technique. For...
Topics: DTIC Archive, Davidson,D L, SOUTHWEST RESEARCH INST SAN ANTONIO TX, *ALUMINUM ALLOYS, *CRACK...
Prototype measurements include static and dynamic values of pressures due to flow in the 66- and 78-in.-diam. Howell-Bunger valves and hoods and strain on one vane of each valve. Transverse, vertical, and peripheral accelerations were measured at the downstream end of the valve cone. Vertical accelerations were also measured on the upstream end of the hood of each valve. Data were recorded on analog magnetic tape and played back on oscillograph charts to verify the recording. Results of the...
Topics: DTIC Archive, Fagerburg,Timothy L, ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MS...
A method of calculating in situ one dimensional stress-strain soil properties from vertical ground motion is presented. The method relies on the fact that superseismic air blast ground surface loadings produce ground motions that are very nearly vertical and one dimensional in character. Therefore the equations of motion that govern the response are simple and may be integrated to obtain one dimensional stress-strain relations. Thus, results from tests that incorporate superseismic air blast...
Topics: DTIC Archive, Frye,John, BALLISTIC MISSILE OFFICE NORTON AFB CA, *Soil dynamics, *Ground motion,...
The purpose of this research was to assess the applicability of geometric scaling at very small scale to study the response of buried reinforced concrete vertical shelter structures subjected to airblast loading. The approach was to build and test two 1/30-scale models and compare the responses with those from corresponding 1/6-scale tests. One of the structures tested was designed to respond elastically, and the other was designed to respond inelastically. The 1/30-scale and 1/6-scale models...
Topics: DTIC Archive, Gran,James K, BALLISTIC MISSILE OFFICE NORTON AFB CA, *Scale models, *Structural...
During the period covered by this report, we drilled ten holes at five sites in Yellowstone National Park. We designed and constructed equipment for recording tilt data at the sites and for transmitting the data to our laboratory in Boulder. We installed instruments at three of the sites and began recording data to our laboratory in Boulder. We installed instruments at three of the sites and began recording data. At the same time, we began a program to analyze the tilt data using the more...
Topics: DTIC Archive, Levine,J, JOINT INST FOR LAB ASTROPHYSICS BOULDER CO, *TILT, WYOMING, TILTMETERS,...
Thermomechanical fatigue (TMF) experiments were conducted on polycrystalline MAR-M 200 over a cyclic temperature range of 500 to 1000 C. Inelastic strain ranges of 0.03 to 0.2 percent were imposed on the specimens. TMF lives were found to be significantly shorter than isothermal low-cycle-fatigue (LCF) life at the maximum cycle temperature, and in-phase cycling was more damaging than out-of-phase cycling. Extensive crack tip oxidation appeared to play a role in promoting the severity of...
Topics: DTIC Archive, Bill,R C, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH LEWIS RESEARCH...
Initial efforts were addressed at the preparation of powders that would result in the development of HIP'd logs possessing a large range of grain sizes and grain size distributions. After several trials, it was determined that the widest range of alloy grain size could be obtaining by using different HIPing temperatures in conjunction with different solution treatments (ST). The following treatments and grain sizes are identified: (1107 C HIP + 1121 C ST (ASTM No. 13)); (1107 C HIP + 1149 C ST...
Topics: DTIC Archive, Hertzberg,R W, LEHIGH UNIV BETHLEHEM PA DEPT OF METALLURGY AND MATERIALS ENGINEERING,...
This report summarizes research on the determination of: (a) the dislocation densities of both edge and screw components using two positron annihilation techniques; and (b) the density of hydrogen traps by analysis of electrolytic permeation measurements. Dislocation densities of single crystal iron specimens deformed in three different manners were in good agreement with disclocation densities obtained by ETCH-PIT and TEM methods on the same specimens as well as being bracketed by three...
Topics: DTIC Archive, Waber,J T, NORTHWESTERN UNIV EVANSTON IL DEPT OF MATERIALS SCIENCE AND ENGINEERING,...
The current research makes use of the boundary integral equation (BIE) method, as modified to account exactly for the elastic crack problem. The usual BIE formulation for elastic problems reduces the numerical problem to one of modeling the boundary data, while preserving the complete interior solution of the field equations. In the elastic fracture mechanics problem, the Green's function approach is used wherein the BIE is modified to account for the presence of a stress free crack at an...
Topics: DTIC Archive, Cruse,T A, SOUTHWEST RESEARCH INST SAN ANTONIO TX, *FRACTURE(MECHANICS), *CRACK...
Dynamic ductile fracture of two phase material have been investigated in two stages. The first stage is a model study where an idealized two phase material, single crystal Cu SiO2 was used to study the initiation and growth of voids, the dislocation morphology and the other microscopic behavior that took place in the as-impacted speciment. Important findings are voids were nucleated from only a fraction of secondary particles SiO2, the larger strain has induced the higher void density, and the...
Topics: DTIC Archive, Taya,Minoru, WASHINGTON UNIV SEATTLE DEPT OF MECHANICAL ENGINEERING, *METAL MATRIX...
Attention is focussed on the asymptotic stress and deformation fields near the edge of a mode I crack propagating steadily in an elastic perfectly plastic incompressible material under plane strain conditions. Features of previously reported results on this problem are reviewed, with a view toward establishing discriminating characteristics. An asymptotic solution valid for all crack speeds is constructed. This solution has the properties that the angular variation of stress and particle...
Topics: DTIC Archive, Leighton, J T, BROWN UNIV PROVIDENCE RI DIV OF ENGINEERING, *CRACK PROPAGATION,...
Rubber to metal bonds are important in a variety of automotive, tire, and marine applications. A new technique is discussed for measuring the strain energy release rates of these adhesively bonded joints in the presence of harsh environments. Guidelines for design and applications are given.
Topics: DTIC Archive, Lefebvre, Didier R, VIRGINIA TECH CENTER FOR ADHESION SCIENCE BLACKSBURG, *BONDED...
Sequential annealing treatments up to 400 C were performed on a severely cold wrought nickel rich Nickel Titanium (NITINOL) alloy to demonstrate the shape memory performance of the alloy as a function of annealing. The strain recovery was 2.75%. The electrical resistance responses associated with the phase transformations of the specimen, subsequent to the various annealing treatments, are shown and interpreted. Supporting data were obtained on the same alloy for varied annealing cycles by use...
Topics: DTIC Archive, Goldstein, David M, NAVAL SURFACE WEAPONS CENTER SILVER SPRING MD, *TITANIUM ALLOYS,...
Results on symmetrizable nonselfadjoint distributed parameter systems are reported on. Operator factorizations are used to characterize the dynamics of a subclass of non-conservative and nonselfadjoint linear distributed parameter systems modeled by partial differential equations subject to various boundary conditions. The results are used to characterize the dynamics of such systems. In addition, the control problem of the validity of using a finite dimensional model in designing a control law...
Topics: DTIC Archive, Inman,Daniel J, STATE UNIV OF NEW YORK AT BUFFALO RESEARCH FOUNDATION, *SPACECRAFT,...
The effects of high-density electric current pulses and a continuous external d.c. electric field on the behavior of metals and alloys was investigated. The theoretical basis for the effects of the current pulses was considered, giving special attention to an electron wind-assisted dislocation motion. It was determined that high-density electric current pulses significantly increased: (a) the plastic strain rate in unidirectional straining at low homologous temperatures, (b) the fatigue life,...
Topics: DTIC Archive, Conrad, Hans, NORTH CAROLINA STATE UNIV AT RALEIGH DEPT OF MATERIALS SCIENCE AND...
Disks of silicon carbide continuous fiber-reinforced (90 DEG)4S aluminum were supported circumferentially on one side and the center of the other side with a pin. maxima principal tensile surface were determined during flexing with strain gages. Failure under monotonic loading initiated on the convex side of the disks with the formation of multiple breaks in the first layer of fibers. With further flexing, cracking extended to inner fiber layers. Finally, fracture extended through the convex...
Topics: DTIC Archive, Tsangarakis, Nikos, ARMY LAB COMMAND WATERTOWN MA MATERIAL TECHNOLOGY LAB, *FIBER...
Equations were developed to predict standoff distances from accidental explosions in magazines sited in rock. The ground threat to adjacent chambers is considered as well as the airblast which vents through the portal. The equations relate freefield motion to geometrical effects (for cylindrical chambers), explosive coupling properties of the medium, and type and quality of explosives. A dimensionless equation was developed which delineates the upper bound of external airblast pressure as a...
Topics: DTIC Archive, Smith, Dennis R, ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MS STRUCTURES...
About a century ago, piezoelectric solids such as quartz and ceramics were discovered. They have been since used as phonograph pickups, transducers and spark igniters for gas stoves, among other things. However, they aren't universally useful. Because of their brittleness, it is difficult to make them into complex shapes, and, because of their high stiffness, they vibrate for a long time, which is undesirable in applications where rapid damping is required. The phenomenon of a material's...
Topics: DTIC Archive, Dutta, Plyush K, COLD REGIONS RESEARCH AND ENGINEERING LAB HANOVER NH, *GAGES,...
This report describes the estimation of crack length values based on back-surface strain measurements in a compact-type, C(T), specimen. The method of crack length determination is well suited for use with closed-loop computer controlled test systems. A finite element analysis is used to determine the theoretical back-face strain values for crack length (a) to width (w) ratios from 0.2 to 0.8 and a mathematical relationship for back-face strain compliance as a function of a/W is derived. The...
Topics: DTIC Archive, Maxwell, D C, AIR FORCE WRIGHT AERONAUTICAL LABS WRIGHT-PATTERSON AFB OH, *CRACKS,...
A one-dimensional, dynamic, thermomechanical model, which includes nonlinear inelastic deformation, internal heat generation (strain-heating), temperature dependent material properties, thermal expansion and thermoelastic coupling, is considered for a uniform thin bar subjected to mechanical or thermal disturbances. A nonlinear Maxwell material is examined in this model and special attention is focused on the temperature change. By solving a nonlinear problem, it is found that a thermal...
Topics: DTIC Archive, Wan, K T, STATE UNIV OF NEW YORK AT BUFFALO AMHERST DEPT OF MECHANICAL AND AEROSPACE...
The report presents an approach to passive vibration control of thin-walled structures utilizing shape memory alloy (SMA) stringers. The stringers represent prestressed superelastic SMA wires sliding within protective sleeves that are either embedded within the structure or bonded to its surface. The vibration control mechanism combines an effective elastic foundation reflecting the support provided by SMA wires to the structure with energy dissipation as a result of the hysteresis occurring in...
Topics: DTIC Archive, MISSOURI UNIV OF SCIENCE AND TECHNOLOGY ROLLA, *ENERGY, *STRUCTURES, *SHAPE MEMORY...
The Final Proceedings for Optimization in Composite Material Design and Structural Integrity, 20 May 2001 - 25 May 2001. This is an interdisciplinary conference. Topics include a review of the application of composite materials to solving practical problems, assisting the structural designer in appreciating the nature of the materials problem, reconciling the inhomogeneity of composite microstructure with the assumed continua of the computational methods, and bringing together the experience of...
Topics: DTIC Archive, CAMBRIDGE UNIV (UNITED KINGDOM) DEPT OF ENGINEERING, *COMPOSITE MATERIALS,...
To respond to the advent of more lethal threats, recently designed aluminum-armor-based military-vehicle systems have resorted to an increasing use of higher strength aluminum alloys (with superior ballistic resistance against armor piercing (AP) threats and with high vehicle-light weighing potential). Unfortunately, these alloys are not very amenable to conventional fusion-based welding technologies and in-order to obtain high-quality welds, solid-state joining technologies such as Friction...
Topics: DTIC Archive, ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD SURVIVABILITY MATERIALS BRANCH,...
Plate-impact experiments were conducted to highlight the high-pressure, high-strain-rate response of a select model poly(urethane urea) (PUU) elastomer impacted against stationary soda lime glass target plates. The dynamic stress-strain behavior reveals that the stress level reaches 0.672 and 3.042 GPa at impact velocities of 298 and 998 m/s, respectively. The PUU is partially unloaded in four successive steps after the initial compression at the impact velocity of 298 m/s and three successive...
Topics: DTIC Archive, ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH...
The theoretical model for the dynamic response of multi-directional functionally graded thin plates under an in-air blast loading from a Friedlander type pressure loading is presented. The theory is presented in the context of the classical linear plate theory (CPT) which is based on the Kirchoff-Love assumptions. The plate is assumed to be thin, in-plane strains are small compared to unity, and the transverse and normal strains are considered to be negligible. Additionally, the theoretical...
Topics: DTIC Archive, ARMY TANK AUTOMOTIVE RESEARCH DEVELOPMENT AND ENGINEERING CENTER WARREN MI, *BLAST...
The results of stress-rupture tests of internally heated and pressurized thin-walled tubes of Type 304 stainless steel are presented. The tubes were immersed in high-purity sodium at 1200 deg F and at a flow rate of 20 ft/sec. A heat flux of 10(exp 6) Btu/sq ft-hr passed through the wall. The heat flux was applied in three modes: steady; 6-min on, 6-min off; and 1-min on, 1-min off. The purpose of these tests is to examine the separate and combined effects on creep behavior of stainless steel...
Topics: DTIC Archive, Shively, Jon H, ROCKWELL INTERNATIONAL CANOGA PARK CA ATOMICS INTERNATIONAL DIV,...
A formulation of the equations governing the large transient deformation of Kirchhoff shells especially suitable for use in finite difference structural response codes is presented. It is shown how these equations are employed in REPSIL, a computer code developed at the BRL for predicting the large deflection of thin elastoplastic shells subjected to blast and impulse loadings. The REPSIL formulation is compared with the somewhat similar formulations used by PETROS 1 and PETROS 2, two closely...
Topics: DTIC Archive, Santiago, Joseph M, ARMY BALLISTIC RESEARCH LAB ABERDEEN PROVING GROUND MD, *COMPUTER...
