bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cycle-Dependent Ratcheting Under Multiaxial Loads Including the Bauschinger Effect and Nonlinear Strain Hardening
Authors: Garud YS 
Published: March 2009

This paper presents a study of the phenomenon of cycle-dependent strain accumulation (ratcheting), especially under multiaxial steady and cyclic loads. The practical significance of ratcheting has become more apparent in recent years in dealing with the design/analysis of pressure-retaining components and structures which may be subjected to certain (reversed) thermal or seismic (dynamic) cyclic loads. A review of experimental observations on the fatigue and ratcheting response of such components suggests that the likely mode of failure (under the noted load combinations) is different from the plastic collapse (as assumed for design basis); this provides an opportunity to reduce the over-conservative safety margin requirements. Based on a brief survey of prior material test data and theoretical evaluations of the ratcheting under multiaxial stress conditions, it is concluded that a proper accounting of the material strain hardening and yield behavior (the Bauschinger effect) under multiaxial stresses is needed and can serve a useful purpose.
The nonlinear strain hardening and the Bauschinger effect are taken into account in this work by using the full implementation of incremental plasticity based on the generalized kinematic-type hardening proposed previously by the author. It is shown that, under certain combined stress conditions, the incremental plasticity predicts continued strain accumulation in each (half) cycle even for a kinematic-type hardening assumption. A number of characteristic observations on ratcheting under multiaxial loads are also predicted.
The case of triaxial steady stress with imposed cyclic strain is analyzed in detail; this is similar to typical loads on a pipe section. For such a case the theory predicts conditions of (local) wall thinning and circumferential growth (in the pipe section) that is limited mainly by the structural considerations. For Type 304 stainless steel and A333 Grade 6 carbon steel a graphical representation is developed showing allowable load combinations for various rates of strain accumulation. A simple relation is proposed between the (steady) primary stress and the (cyclic) secondary stress for a specified total ratchet strain as a criterion which is discussed with reference to the ASME Code. The extent of over-conservatism associated with the neglect of material strain hardening and with the (change in) mode of failure can be better judged by means of the results presented here. The paper is concluded with a discussion of related issues and the future direction.
Development of a Stainless Corrosion Resistant Carburizing Bearing Steel
Authors: McCaffrey TJ , Wert DE 
Published: March 2009

The development of a stainless corrosion resistant carburizing bearing steel by Carpenter Technology Corporation is detailed. The alloy, Carpenter VIM-VAR Pyrowear® 675 Stainless alloy, has corrosion resistance equivalent to Type 440C stainless, combined with fracture toughness superior to any martensitic stainless steel and equivalent if not superior to normal noncorrosion resistant carburizing bearing steels such as SAE Type 8620 or 9310.
The discussion will include case and core properties, and carburizing techniques employed to optimize case structures.
The alloy is capable of maintaining a case hardness of HRC 59 at 329°C (625°F). This capability, along with superior fracture toughness compared to both the currently used M50 and the newly developed M50NiL, makes it a viable candidate for main shaft bearings for turbojet engines.
A Ferritic-Pearlitic Steel with Eutectoid Composition
Authors: Andersson-Drugge I-M , Lund T 
Published: March 2009

By alloy design based on demands for formability and high martensitic hardness, a new high-carbon, low-alloy steel has been developed. The steel, which minimizes the use of all elements except carbon and molybdenum, exhibits a microstructure and properties normally not attained in high-carbon steels. On retarded cooling, the steel, which has eutectoid composition, generates substantial amounts of pro-eutectoid ferrite in combination with a coarse, degenerated pearlite. The pro-eutectoid is not ferrite, but an eutectoid itself composed of nanometer-sized, evenly distributed molybdenum carbides and ferrite.
The new steel provides a soft and formable structure in the as-rolled condition, and hardens to high martensitic hardness at austenitization conditions equal to those used for high-carbon, low-alloy steels.
Spontaneous Ignition Temperature of Tracheal Tubes
Authors: Wolf GL , McGuire JG , Nolan PF , Sidebotham GW 
Published: March 2009

Operating room fires continue to be reported in the medical literature. To simulate operating room conditions, a high pressure spontaneous ignition apparatus was redesigned to allow for the determination of spontaneous ignition temperature of trachea! tubes in 100% oxygen at atmospheric pressure. Pure oxygen flowed through a test chamber at 100 cm3/min, and a temperature ramp rate of 10°C/min was used. Sample temperature, chamber temperature, chamber pressure and elapsed time were stored on-line by computer. The experimental ignition temperature was observed as a spike in sample temperature-time plot.
Five samples each of poly (vinyl chloride), red rubber and silicone rubber tracheal tubes were analyzed for spontaneous ignition temperature, which were determined to be 428°C, 371°C, 381°C, respectively.
It was concluded that the small differences in spontaneous ignition temperature for the various tracheal tube materials has little clinical relevance to the tubes chosen for the particular surgical procedure.
Evaluation of Bronze Alloys for use as Wear Ring Material in Liquid Oxygen Pump
Authors: Yentzen MJ 
Published: March 2009

The selection of materials for wear parts in oxygen pumps or compressors is critical from an oxygen compatibility perspective because the function of the part is to absorb frictional energy. Part of this energy is absorbed by the sample as heat and can cause ignition of the material. There is little data on the compatibility of bronze alloys typically used for wear parts in oxygen systems, so it is difficult to ensure that the most compatible materials are used.
This paper discusses frictional heating test data obtained for seven bronze alloys which could be used in certain applications as wear parts. A test apparatus developed by the NASA test facility at White Sands to determine the resistance of materials to ignition by friction was used to obtain the data. The bronzes evaluated were selected based on the ability to function mechanically in the intended application and the anticipated resistance to ignition by friction. The alloys were ranked according to the resulting pressure-velocity (PV) product. This factor serves as a measure of the load required for ignition given a constant sample load rate, a constant gaseous oxygen pressure, and a constant sample rotational velocity. Factors influencing the test results including sample composition, material properties, and test procedures are addressed. A simple theoretical description of the phenomenon of ignition by friction is presented to explain the effects that the proposed variables may have on the PV product.
Combustion Characteristics of Polymers as Ignition Promoters
Authors: Shelley RM , Wilson DB , Beeson H 
Published: March 2009

Four polymers, which were high density polyethylene (HDPE), polytetrafluoroethylene (PTFE), unfilled polyimide (PI), and graphite-filled polyimide (GPI), were burned in high pressure oxygen over the range 0.7 to 69 MPa. Three metallic materials were used as support rods: aluminum 2216, stainless steel 316, and pure copper. Flame characteristics of the polymers are described, as well as the polymer potential for igniting the metal support.
HDPE burns at all pressures with a diffusion flame, PTFE burns at all pressures as a surface burner, PI and GPI are combined surface and diffusion flame burners. Flame compositions and temperatures were estimated based on computer calculations (Gordon McBride) and experimental melting characteristics of the aluminum rods.
Diffusion Bonding Between Vanadium and Alumina
Authors: Abe K , Okamura K , Kikuchi M 
Published: March 2009

Joining with ceramic materials is one of the important subjects in the application of vanadium for the fusion environment. In order to develop and understand the solid-state bonding of vanadium with oxide ceramics, conditions of diffusion bonding between vanadium and alumina were examined, and fundamental properties of bonded couples were studied. As alumina has a linear thermal expansion coefficient relatively close to the value of vanadium, enough bond strength is expected between them.
Couples of vanadium and alumina disks with 8-mm diameter and 3-mm thickness were heat-treated in a vacuum of 1 × 10-3 Pa in the temperature range of 1673 to 1873 K under the compression of 2.8 to 14.6 MPa. Both single crystals and polycrystals of alumina and a polycrystalline vanadium were used. The degree of bonding depended on the temperature and stress. In the case of alumina single crystals, relaxation of residual stress could be accompanied with crack nucleation and also twin-like deformation.
Transmission electron microscopy and electron-probe X-ray microanalysis were performed in the region including the metal/ceramic interface. Both straight and curved interfaces were observed along with several orientation relationships across the interface. No intermediate phase was observed by transmission electron microscope (TEM) and electron probe micro-analysis (EPMA), nor was a hardened layer on the vanadium side near the interface observed by the micro Knoop indentation technique.
The maximum strength of bonded couples was determined to be 83 MPa for the polycrystalline alumina by means of a miniature three-point bend test. Scanning electron microscopy showed a relatively wavy fracture mode along the interface.
The bonding mechanism and the method to improve bond properties are discussed.
A Fracture Mechanics Test Automation System for a Basic Research Laboratory
Authors: Hartman GA , Ashbaugh NE 
Published: March 2009

Successful selection of a material test automation strategy, hardware, and software depends on careful evaluation of the requirements of the target laboratory. Some of the criteria include the type of testing (single event, continuous), the laboratory mission (basic research, production testing, quality assurance), the operator's level of understanding of the testing and automation system, the available laboratory space, and the financial constraints. This paper discusses automation strategy, hardware, and software that have been used to automate a basic research laboratory performing fatigue crack propagation testing under a variety of test conditions including elevated temperatures.
A microcomputer and smart peripheral equipment are used as a hardware platform to perform real-time test control. The material analysis and test environment (MATE) software has been developed in-house to satisfy a broad range of current and future requirements. MATE is discussed in terms of its ability to meet the criteria set forth for the laboratory both for real-time automated test control and for quasi-real-time analysis of the data as the test proceeds. The software is designed to provide maximum flexibility as demanded by the basic research mission of the laboratory. The software presents a logical graphical operator interface to the user that is suitable for use by the technical and scientific staff.
Collection and Evaluation of Fatigue and Fracture Mechanics Data According to the European High Temperature Materials Databank (Petten) Standard
Authors: Over H-H , Buchmayr B 
Published: March 2009

Well-organized material databanks present obvious advantages to material scientists as well as to designers. The capacity, efficiency, reliability, and acceptance of material databanks, among others, depend on the documentation of the data sources, the structure of the data, and the sophistication of the evaluation and assessment facilities.
The European High Temperature Materials Databank (HTM-DB) of the Joint Research Centre (CEC-JRC) Petten is organized in such a way that an optimum data storage enabling rational data collection and evaluation is achieved. In the area of high-temperature materials testing, where the material behavior (for example, lifetime of components) is strongly affected by the loading conditions and control parameters, the HTM-DB relates to this by defining the appropriate terms and fields. In this sense, it contributes to the standardization of automated testing technology.
In addition, the HTM-DB offers several well-defined standardized evaluation methods for the results of tensile, creep, relaxation, fatigue, creep-fatigue, creep crack, and fatigue crack growth testing at high temperatures. The results of these evaluation programs can be implemented for the design of components using finite element calculations or for material development tasks.
Analysis of Quick Load Tests on Stone Columns: Case Histories
Authors: Hussin JD , Baez JI 
Published: March 2009

This paper examines 6 stone column projects constructed throughout the United States from 1985 to 1988 in which quick vertical load tests were performed to predict performance of foundations and to compare this prediction with the design prediction. The stone columns were constructed through various types of soil including sand, clay, silt, peat and construction debris. The configuration of the load tests varied from .76 m (30 inch) diameter to 1.8 m (6 foot) square steel plates with loads from 89 kN to 916 kN (10 to 103 tons) on one to four stone columns.
The proposed construction, design load, settlement criteria and soil profile are reviewed for each project. Special emphasis is placed on using the load test data to predict the settlement of the planned foundations. In addition, the configuration and mechanics of the load test set ups are presented.
Leak Detection Methods for Airport Hydrant Systems
Authors: Flora JD , Glauz WD , Hennon GJ 
Published: March 2009

Airport hydrant systems are large underground pressurized piping systems. Typically, these systems operate with a pressure of about 150 psi and range in diameter from 6 in. to 16 in.. Systems vary in their design, but typically have trunk lines and laterals that end in hydrant pits. These systems are orders of magnitude larger than piping systems found at retail fuel outlets. The lines themselves may contain 250 000 to 500 000 gal of product. Since they are large and operate at high pressure, the potential for environmental damage in the event of a leak is correspondingly increased.
Airport hydrant systems are currently deferred from the leak detection requirements of the federal EPA regulations covering underground storage tanks. However, several states, eg. Texas, have neither exempted nor deferred these systems. These states are regulating hydrant systems on a case by case basis. There is a clear need for leak detection methods for such systems.
A number of approaches to leak detection for hydrant systems have been proposed. These include double wall piping with interstitial monitoring, external monitoring methods for vapor or liquid product on the water table, tracer methods, pressure-step methods, and inventory methods. This paper describes several approaches to leak detection for hydrant systems. It also provides estimates of the performance that may be expected from each method. It relates these performance estimates to the EPA standards for nonexempt/nondeferred systems. The approximate cost to install and operate the methods is discussed.
Processed Guar Gum in Agricultural Applications: New Interest for an Old “Inert”
Authors: Hazen JL 
Published: March 2009

The endosperm of Cyamopsis tetragonolobus (L.) Taub. is better known as guar gum. This material has been known to the agricultural chemical formulation industry for many years. Nevertheless, this poly-saccharide is generally overlooked during formulation development work, in favor of more expensive natural and synthetic polymers.
Recent work with natural and derivatized guar has shown certain performance and economic advantages when guars are used in conjunction with other rheology-modifying polymers. These varied applications include suspension concentrates, suspoemulsions, agglomeration, extrusion, gellation, and adhesion.
This paper reviews the nature of guar and derivatives in terms of structure and rheological properties. Suggested applications are presented in terms of performance enhancement. Opportunities to optimize formulations utilizing the replacement and synergy value of guar derivatives are emphasized.
A Calibrated Method for Crystallinity Determination of Hydroxylapatite Coatings
Authors: Flach JS , Shimp LA , van Blitterswijk CA , de Groot K 
Published: March 2009

A quick and inexpensive method was developed to determine the crystallinity of hydroxylapatite coatings using X-ray diffraction for the purpose of production control.
Crystalline hydroxylapatite powder, when sprayed onto a substrate with thermal spraying, forms a mostly two phase material consisting of crystalline hydroxylapatite and amorphous material and very likely some trace impurities. The term crystallinity of a thermal sprayed hydroxylapatite coating is defined as the weight percentage of crystalline hydroxylapatite material to the total amount of material in the coating. With X-ray diffraction of the coating, the integrated crystalline hydroxylapatite peak intensity between 25° and 40° (2⊖) is measured and divided by the same integrated intensity of a 100% crystalline hydroxylapatite standard. The ratio between both is called the crystallinity of the hydroxylapatite coating. The method is calibrated using crystallinity standards which have been made by mixing 100% crystalline hydroxylapatite powder with 100% amorphous powder in different ratios.
Elimination of IR Error in Measurements of Corrosion in Concrete
Authors: Escalante E 
Published: March 2009

The deterioration of concrete bridge decks owing to the corrosion of imbedded steel has generated interest in developing techniques to measure the corrosion of steel in this high-resistivity environment. Several electrochemical polarization methods have been used successfully in the laboratory. This paper describes the use of current interruption to eliminate the IR that arises in measuring the potential of steel during polarization measurements.
Polarization measurements were carried out using a small, portable computer system that controlled and monitored the potential of the steel and the applied current. Current was cycled on and off, with the potential measured during the off cycle and the current during the on cycle. The duty cycle was 2.2 s on and 0.4 s off, and sampling of the voltage occurred approximately 75 ms after the current was interrupted. Results indicated that 95% of the error is eliminated using this technique.
Pesticide Drop Size as a Function of Spray Atomizers and Liquid Formulations
Authors: Akesson NB , Gibbs RE 
Published: March 2009

The use of the ruby laser automatic, in situ spray drop size and frequency analyzer has permitted a much more detailed, rapid and reproducible study of spray drop atomization than hitherto possible. With the advent of these machines and their use in pesticide spray studies, it is now possible to enumerate specific size and size range for the many different atomizers, fan, cone, jet hydraulic pressure types and rotary screen devices used for pesticide spraying. A given atomizer will respond to formulation changes as these affect surface tension, viscosity and density and will produce drop size in relation to these physical properties.
As a result of several years collection of field drift-loss data we have put together a model program which utilizes the drop size information as noted, combines this with weather factors and operational parameters of the spray aircraft to enable prediction of amounts of pesticide to be expected as fallout and airborne portion at specified distances downwind. This information will be of significant value to pesticide manufacturers, users and to registration and regulatory agencies charged with safe use of pesticide chemicals.
Thermomechanical, Time-Dependent Analysis of Layered Metal Matrix Composites
Authors: Lee K-D , Krempl E 
Published: March 2009

The orthotropic, thermal viscoplasticity theory based on overstress (TVBO) is specialized for plane stress in a simple laminate theory. It maintains the same geometric assumptions as the classical laminate theory except that the orthotropic linear elasticity law is replaced by TVBO. In this way, rate sensitivity, creep, and relaxation can be modeled without the use of a yield surface and loading/unloading conditions. The laminate theory is intended for thermal analysis of metal matrix composites operating at high temperature under simultaneous mechanical and thermal loadings.
The rate-dependent laminate behavior is described by a set of coupled, first order, nonlinear differential equations that must be numerically integrated for a given mechanical and thermal history to yield the laminate and ply stresses as well as the laminate total strain as a function of time. To describe the behavior, the elastic constants and the coefficients of thermal expansion need to be known in addition to two material functions and six constants that describe the inelastic deformation behavior. Two metal matrix composites, MMC1 and MMC2, are constructed theoretically. For MMC1, the strength in the fiber and the transverse directions decrease with temperature. The strength in the transverse direction of MMC2, patterned after Ni3Al/Al2O3, increases with temperature before it decreases and the strength in the fiber direction is nearly constant. First, the ply behavior is simulated by off-axis m-phase and out-of-phase thermomechanical numerical tests. Then the behavior of a [±45]s laminate under a temperature excursion is computed both when it is free to expand and when the laminate is clamped in one direction. After the temperature returns to the datum point, residual stresses are shown to redistribute in time. They are induced by prior inelastic deformation.