| Materials and Manufacturing Processes, Volume 10, Number 4, 1995 |
95 |
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| Authors:
T. S. Sudarshan; T. S. Srivatsan; MARCEL DEKKER INC NEW YORK
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 | Materials and Manufacturing Processes treats such issues as more efficient use of raw materials and energy, integration of design and manufacturing activities requiring the invention of suitable new manufacturing processes, unmanned production dependent on efficient and reliable control of various processes, introduction of new materials in industrial production necessitating new manufacturing process technology, and more. Information is offered in various formats, including research articles, short reports, review articles, conference papers, ... |
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| Synthesis and Consolidation of Nanoparticles |
JUL 94 |
22 pages |
| Authors:
T. S. Sudarshan; Jacob J. Stiglich; R. J. Dowding; MATERIALS MODIFICATION INC FAIRFAX VA
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 | Nanomaterials synthesis and characterization have been very active development fields for many years, motivated by the prospect of extremely high mechanical properties coupled with useful plasticity and elevated temperature properties. We will briefly review the history of nanomaterials research, describe the principal synthesis routes for particles, and review the availability of consolidation technology capable of producing shapes which may demonstrate the physical properties which researchers have predicted and expected. We ... |
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| Hydrogen and Temperature Effects on the Slow Bend Behavior of 21-6-9 Stainless Steel |
1994 |
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| Authors:
D. P. Harvey II; J. B. Terrell; T. S. Sudarshan; NAVAL RESEARCH LAB WASHINGTON DC MATERIAL SCIENCE AND TECHNOLOGY DIV
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| This paper concerned metals in some important way and contained information about, utilized, or discussed these subjects: basic topics: experimental materials and material types: 21-6-9 materials related terms: austenite, chromium addition, elongation, fractography, hydrogen charging, hydrogen embrittlement, manganese addition, microvoid coalescence, nickel addition, reduction of area, tensile yield strength, ultimate tensile strength parameter values relevant to the data: temp -273 to -151 c, temp 0 to 99 c testing and ... |
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| Hydrogen Effects on the Ductile to Brittle Transition Behaviour of 21-6- 9 Stainless Steel |
1994 |
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| Authors:
D. P. Harvey II; J. B. Terrell; T. S. Sudarshan; NAVAL RESEARCH LAB WASHINGTON DC
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| Charpy v-notched impact test studies on 21-6-9 austenitic stainless steel at 293 and 77 k demonstrated that hydrogen charging promoted the formation of larger microvoids at 293 k, promoted the formation of facets at 77 k, and reduced the energy absorbed by the material at both temperatures. these observations suggest that the role of hydrogen in the impact behaviour of this material is to enhance whatever crack-growth mechanism is operating ... |
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| Materials and Manufacturing Processes. Volume 9. Number 1 |
94 |
190 pages |
| Authors:
T. S. Sudarshan; T. S. Srivatsan; MATERIALS MODIFICATION INC FAIRFAX VA
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| Materials and Manufacturing Processes is a journal in the English language providing an international forum for current developments and future direction in the area of materials and manufacturing processes. Manuscripts may fall into several categories including full articles, solicited reviews, or commentary, unsolicited reviews or commentary, and patent and book reviews. |
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| Materials and Manufacturing Processes. Volume 9. Number 2 |
94 |
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| Authors:
T. S. Sudarshan; T. S. Srivatsan; MATERIALS MODIFICATION INC FAIRFAX VA
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| Contents: Processing of Carbon Fibers: Texture Enhancement Induced by Hot Stretching; Carbon Fiber Processing: Effects of Hot Stretching on Mechanical Properties; Carbon Fibers from Polyethylene-Based Precursors; Rapid Vapor Grown Carbon Fiber Production Using the Intermittent Liquid Pulse Injection Technique; Preparation of Metal-Coated Carbon Fiber Reinforced Composites and Their Electromagnetic Properties; Electrolytic Metallic Coatings for Carbon Fibers; Processing and Heat Treatment Effects on an Al2O3/Ni3Al Composite; Fiber Metal Laminates-The Synthesis of ... |
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| Materials and Manufacturing Processes. Volume 9. Number 3 |
94 |
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| Authors:
T. S. Sudarshan; T. S. Srivatsan; MATERIALS MODIFICATION INC FAIRFAX VA
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| This paper addresses the feasibility of friction welding as an approach to join aluminum to ceramics. Potential advantages include the localised heating below the melting point of the parent materials, and the short time required to produce the bond. Metal/ceramic combinations examined include aluminum/silicon nitride, aluminum/silicon carbide, aluminum/zirconia and aluminum/aluminum nitride. |
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| Materials and Manufacturing Processes. Volume 9. Number 5. 1994 |
94 |
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| Authors:
T. S. Sudarshan; T. S. Srivatsan; MATERIALS MODIFICATION INC FAIRFAX VA
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| Partial contents: Processing of Bamboo Fiber Reinforced Plastic Composites; Effects of Processing Variables on Fatigue in Molded PEEK and Its Short Fiber Composites; PC-Based Monitoring and Control System for Microwave Curing of Polymer Composites; Densification Rates of Ceramic Matrix Composites with Initial Matrix Inhomogeneity; The CVD of Ceramic Protective Coatings on SiC Monofilaments for Use in Titanium Based Composites; C.V.D. Coating of Alumina Reinforcing Particles to Improve the Wear Resistance ... |
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| Materials and Manufacturing Processes. Special Issue on Refractory Metals and Alloys. Volume 9, Number 6 |
94 |
|
| Authors:
T. S. Sudarshan; T. S. Srivatsan; MARCEL DEKKER INC NEW YORK
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| Solid Lubricants for Space Structures. Phase 2 |
14 JUN 93 |
97 pages |
| Authors:
T. S. Sudarshan; MATERIALS MODIFICATION INC FAIRFAX VA
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| In this Phase 11 effort, copper-lead alloys of three different compositions (90-10, 75/25, and 50/50 copper-lead) were processed by swirl die continuous casting in the form of ingots and further processed into powders using the gas atomization method. The powders were compacted using shock campaction and hot isostatic pressing. Friction and wear studies revealed that the 75/25 alloys had the best friction and wear rates under a range of sliding ... |
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| Materials and Manufacturing Processes. The Electroimpact Compaction of Powders: Mechanics, Structure and Properties. Volume 8, Number 3 |
MAY 93 |
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| Authors:
T. S. Sudarshan; T. S. Srivatsan; MATERIALS MODIFICATION INC FAIRFAX VA
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| Topics include: The electroimpact compaction of powders: mechanics, structure, and properties; Laser processing of metallic and intermetallic surfaces; Thin alumina and silica films by chemical vapor deposition (CVD); CVD of silicon nitride plate from HSiCI3-H2 mixtures; Single-pass curtain coating; and Review of some processes for ceramic-to-metal joining |
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| Modelling and Experimental Studies of Properties of TiN Coatings |
93 |
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| Authors:
S. Chatterjee; T. S. Sudarshan; S. Chandrashekhar; NEW EAGLE COMMUNICATIONS GROUP SILVER LAKE KS*
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| This paper reviews pertinent research in the area of theoretical modeling and experimental studies of the various properties of titanium nitride coatings. A brief description of methods commonly used for the deposition of TiN coatings is discussed first. The important properties of these coatings are presented next. Various theoretical models for hardness, adhesion, and residual stresses, and experimental work, both in support of these models and on other relavent properties ... |
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| Materials and Manufacturing Processing; Special Issue on Hard Carbon Films |
93 |
139 pages |
| Authors:
T. S. Sudarshan; T. S. Srivatsan; MATERIALS MODIFICATION INC FAIRFAX VA
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| Laser processing of polycrystalline diamond and amorphous carbon films is shown to be a promising technology for micropatterning of these materials in electronics and other applications. By using excimer lasers, holes and pits have been formed in 10-60 micrometers thick diamond films by physical etching with ablation rates of up to 300 nm/pulse. The channels of micrometer scale width were created in diamond-like carbon films on silicon by chemical etching ... |
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| Materials and Manufacturing Processes. Special Issue on Ceramic-Metal Joining. Volume 8, Number 2 |
93 |
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| Authors:
T. S. Sudarshan; T. S. Srivatsan; MATERIALS MODIFICATION INC FAIRFAX VA
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| In this paper the technology for joining metals to ceramics is reviewed. The technologies of metal powder sintering, liquid phase joining with activated brazing alloys and with ceramic frit, solid-state joining, friction welding and mechanical fixation are described. In order to put some perspective on the mechanical data given in the literature, some evaluating remarks on mechanical testing are made. |
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| Materials and Manufacturing Processes, Volume 8, Numbers 4 and 5, 1993 |
93 |
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| Authors:
T. S. Sudarshan; T. S. Srivatsan; MATERIALS MODIFICATION INC FAIRFAX VA
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| Partial Contents: Preparation, Properties and Structure of Metal Containing Amorphous Hydrogenated Carbon Films; Use of Thin Solid Films at Head/ Magnetic Media Interfaces; Laser Induced Microcrystallization of Bulk Amorphous Ge15Se(85-x)Te(x); Superconductive Films by Laser Post-treatment of Thermal- Sprayed Films; Development of Plasma Sprayed Lubricant Free Slide Plates with Ceramic Coat for Railway Use; The Thermal Shock Endurance of a Plasma Sprayed ZrO2 Coating on Steel; Solid Solution Approach for the ... |
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| Influence of Nitrogen Ion Implantation on Tensile Behavior of 1018 Carbon Steel |
92 |
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| Authors:
T. S. Srivatsan; Mike Hanigofsky; T. S. Sudarshan; Keith O. Legg; AKRON UNIV OH DEPT OF MECHANICAL ENGINEERING
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| Ion implantation is shown to be an effective tool for the modification of surface microstructures such that they can have a profound influence on the mechanical properties of metals and alloys. In this paper, the influence of nitrogen ion implantation on tensile behavior of low carbon steel 1018 is reported. The tensile properties of the implanted material are compared with those of the unimplanted counterpart. Implantation was found to decrease ... |
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| Tensile Behavior of Ni3Al+B Intermetallic Compound: Influence of Cold Deformation and Annealing |
92 |
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| Authors:
T. S. Srivatsan; S. Anand; S. Sriram; T. S. Sudarshan; AKRON UNIV OH DEPT OF MECHANICAL ENGINEERING
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| Nickel aluminide, intermetallic compound Ni3Al, is a promising structural material on account of its high strength at elevated temperatures. The influence of cold deformation on the tensile behaviour of an Ni3Al alloy containing zirconium and boron is presented. The undeformed material, in the as- cast condition, was subjected to varying levels of cold deformation ranging from 11.4%-61.4%, and tensile tests performed. The tensile properties and fracture behaviour of the cold-deformed ... |
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| Deposition Processes and Metal Cutting Applications of TiN Coatings |
92 |
|
| Authors:
S. Chatterjee; S. Chandrashekhar; T. S. Sudarshan; WESTERN NEW ENGLAND COLL SPRINGFIELD MA*
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| The processing techniques and metal working applications of titanium nitride (TiN) coatings are reviewed. The principal processing techniques are physical vapor deposition (PVD) and chemical vapor deposition (CVD). Individual processes within CVD and PVD are reviewed and the important process parameters identified. Various metal working applications of TiN-coated tools in turning, milling, drilling and other processes, are also reviewed. Finally, future trends and needs in the development and application of ... |
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| Welding of Lightweight Aluminum-Lithium Alloys |
91 |
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| Authors:
T. S. Srivatsan; T. S. Sudarshan; AKRON UNIV OH DEPT OF MECHANICAL ENGINEERING
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| Lithium-containing aluminum alloys have generated much interest in the aerospace industry because lithium additions to aluminum can decrease the density and improve the stiffness compared to conventional aluminum alloys of comparable strength; in this paper, published studies of the structure and properties of welded aluminum-lithium alloys are discussed; the weldability characteristics of these lightweight alloys using gas metal arc, gas tungsten arc, electron beam and laser beams are summarized; while ... |
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| Tensile Fracture of Al-Li-Cu-Mg-Zr Alloy 8090 |
91 |
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| Authors:
Tirumalai S. Srivatsan; T. Alan Place; T. S. Sudarshan; AKRON UNIV OH DEPT OF MECHANICAL ENGINEERING
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| Microstructural effect on the fractural high-strength, low-density Al-Li alloy was studied; a change in fracture mode depends on test direction; the results are explained terms of grain structure of the material and the distribution, nature, and morphology of 2nd-phase particles; deformation characteristics of the matrix resulting in large stress concentrations at the grain boundary, presence of a grain boundary particles, completing mechanistic effects involving matrix microstructural features, and microstructural damage ... |
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| Corrosion Behaviour of a Quaternary Al-Li-Cu-Mg Alloy in 3.5% NaCl Solution |
90 |
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| Authors:
T. S. Srivatsan; T. S. Sudarshan; G. E. Bobeck
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| The corrosion resistance of a quaternary Al-Li-Cu-Mg 8090 alloy in the peak aged condition was evaluated in aqueous environments over a range of aggressiveness. The corrosion rate was established through weight loss measurements obtained in total immersion tests. These measurements show a steady loss of material in the aqueous solutions: corrosion rates were observed to decrease with time of immersion. The pH of solutions changed during the period of testing. ... |
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| Fracture of Precipitation Strengthened Aluminum Alloys-Role of Environment |
90 |
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| Authors:
T. S. Srivatsan; T. S. Sudarshan; AKRON UNIV OH DEPT OF MECHANICAL ENGINEERING
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| Several structural applications demand service of a structural member in aggressive gaseous and aqueous environments; fatigue studies have focussed on gaseous and aqueous environmental effects on fatigue crack initiation and crack growth, and little attention has been given to an understanding of the underlying mechanisms governing fracture in different environments; ductile and brittle fracture in inert environments, and the influence of both inert and aggressive environments on the fracture behavior ... |
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| ELECTROMAGNETIC MEASUREMENT OF DAMPING CAPACITY TO DETECT DAMAGE IN ADHESIVELY BONDED MATERIAL |
MAY 89 |
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| Authors:
T. S. Srivatsan; R. Mantena; R. F. Gibson; T. A. Place; T. S. Sudarshan
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| there have been few attempts to systematically record the role of heterogeneities and defects such as internal cracks, pores, and voids on the performance of adhesively joined structures. in this study, contributions from intrinsic defects caused by improper curing, induced porosity, and improper surface preparation on the performance of double-lap adhesive joints bonded with a structural epoxy adhesive have been nondestructively evaluated through damping-capacity measurements. the damping measurements were made ... |
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| Environmental Factors Affecting Localized Corrosion of Al-Li-Cu-Mg Alloys |
1989 |
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| Authors:
T. S. Srivatsan; G. E. Bobeck; T. S. Sudarshan; P. A. Molian; AKRON UNIV OH
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| The corrosion behavior of 8090 and Navalite Al-Li alloys has been investigated in NaCl solutions of varying pH. Analysis procedures include weight loss and microstructural analysis. Weight loss was observed in all the solutions. Corrosion rates decreased with time in both acidic and basic NaCl solutions. |
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| Susceptibility of a Dual Phase Steel to Hydrogen Embrittlement, |
OCT 1985 |
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| Authors:
T. S. Sudarshan; N. C. Pruitt; M. R. LOUTHAN JR.; T. A. Place
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| Dual phase steels are used in many applications for which electroplating is required. Hydrogen absorption and consequent loss of strength and ductility is therefore possible. Tensile tests and subsequent fractographic analysis of charged and uncharged specimens of a dual phase steel showed that hydrogen absorption resulted in deterioration of tensile properties. The deterioration was attributed to weakening of interfaces between ferrite and other constituents. |
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| Role of Hydrogen and Humidity in the Torsional Fatigue of Aluminum Alloy 2024-T351, |
AUG 1985 |
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| Authors:
T. S. Sudarshan; M. R. LOUTHAN JR.; T. A. Place; H. H. Mabie
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| Reverse torsional fatigue tests conducted on aluminum alloy 2024-T351 samples exposed to argon, hydrogen and humid air environments showed that hydrogen absorption promotes multiple crack initiation and alters the fracture mode. The change in fracture mode was attributed to hydrogen-induced local overaging and interfacial weakening near the crack tip. The humid air environments produced hydrogen at high fugacities because of the reaction between water vapor and aluminum and caused greater ... |
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| Effect of Hydrogen Charging on the Torsional Fatigue Behaviour of 2024 Aluminium, |
JUL 1985 |
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| Authors:
T. S. Sudarshan; T. A. Place; M. R. LOUTHAN JR.; H. H. Mabie
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| Extruded 2024-T351 was machined into smooth torsional fatigue specimens. Specimens were aged at 250 F for 7-days, followed by heat treatment in air or high-pressure hydrogen. Fatigue tests were conducted at room temperature in torsion (R = -1) at 30 Hz in either moist or dry air, dry hydrogen or dry argon. The fatigue lives and number of fatigue propagation facets are tabulated as a function of test environment. |
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| Humidity Effects on the Fracture Mode Transition in Anodized 2024-T351 Aluminium |
SEP 84 |
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| Authors:
J. H. Wilson; T. S. Sudarshan; H. H. Mabie
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| Torsional fatigue tests (Mode III loading) were conducted on anodized 2024-T351 aluminum at low (15 to 20%), medium (50 to 55%) and high (90 to 95%) relative humidity. The alteration of local stress has been used to explain observations of hydrogen effects on metals. Oriani has suggested that at low hydrogen contents (low humidity) the mechanism of embrittlement is predominantly one of tensile decohesion while Lynch argues that at high ... |
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| fatigue characteristics of cu-ni/steel weldments for cladding ship hulls |
11 SEP 83 |
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| Authors:
J. H. Wilson; T. S. Sudarshan; s. m. fisher; m. r. louthan; D. Frederick
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| fatigue tests of 90-10 copper nickel plate material have shown that shielded metal arc welding of the plate to mild steel reduces the endurance limit and fatigue life of the copper-nickel alloy. the results of the copper- nickel fatigue study indicate that although the welding process degrades the fatigue performance, the welding induced degradation is no greater than that observed at a v-notch in the copper-nickel and therefore would not ... |
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| The Ageing of Electrical Insulation at Cryogenic Temperatures, |
APR 81 |
|
| Authors:
A. Bulinski; J. Densley; T. S. Sudarshan
|
| This paper presents some theoretical and experimental evidence, that, under certain conditions, the transient voltage characteristics of electrical insulation impregnated with liquid nitrogen become the limiting factor in determining the normal operating stress. The life of the insulation is assumed to obey the well known life equation: (stress) n x time - constant. It will be shown that the operating stress will depend upon the switching and lightning impulse strengths ... |
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| Investigations of Pulsed Vacuum Gap |
10 FEB 81 |
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| Authors:
J. E. Thompson; T. S. Sudarshan; J. M. Butner; SOUTH CAROLINA UNIV COLUMBIA DEPT OF ELECTRICAL AND COMPUTER ENGINEERING
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| Past research and the current status of understanding of electrical breakdown of vacuum is reviewed. This review includes DC, AC and pulsed vacuum gap breakdown. Measurements have been performed to determine the role of microparticles in pulsed vacuum gap breakdown. These measurements consisted of directly measuring the charge and velocity of microparticles produced using pulsed excitations up to 100kV. Measurements show that microparticles are present prior to, during, and after ... |
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