bluuebunny/crossref_metadata_2025_split huggingface dataset:
A New Application of Normalization: Developing J-R Curves from Displacement Versus Crack Length and from Displacement Alone
Authors: Lee K , Landes JD 
Published: March 2009

Two new experimental approaches are presented in this study to develop J-R curves: (1) from displacement versus crack length without load measurement and (2) from displacement alone without load and crack length measurement. The approaches are new applications of the method of normalization, which is based on the principle of load separation suggested by Ernst et al. The latest version of the method of normalization introduced by Landes et al. uses the three-parameter LMN functional form to relate the three variables, load, displacement, and crack length. Given any two, the third can be determined. Previously, the method of normalization has been successfully used to develop J-R curves from load versus displacement without measuring crack length and from load versus crack length without measuring displacement. The new approaches can be applied to develop J-R curves for the crack-line wedge-loaded specimen, C(W), for which the load cannot be measured.
This study was conducted in two steps. In the first step, the method of normalization was used for developing J-R curves from displacement versus crack length without load measurement. A power law fit was used to determine some calibration points at the initial part of the deformation curve. They are needed for evaluating the LMN function. In the second step, normalization was used to develop J-R curves from displacement only, without load and crack length measurements. Two new equations that relate load, displacement, and crack length were proposed in this study to use with the method of normalization for predicting the load and crack length from displacement measurements alone.
The approaches developed in both steps have been applied to analyze a number of test results from compact specimens for which all of three variables, load, displacement, and crack length, have already been determined. Five different steels were included. For the first approach the test records were assumed to have only the displacement and crack length measurements, while for applying the second approach, the test records were assumed to have only a displacement measurement. The results show that both new approaches worked very well. Compared with the test data, the predicted error for the load measurement was found within 5% for the first approach and 10% for the second approach. Compared with both the standard compliance method and the regular normalization method, the difference between J-R curves developed was found within 5% for both new approaches.
Crack Growth Under Small Scale and Transition Creep Conditions in Creep-Ductile Materials
Authors: Saxena A , Yagi K , Tabuchi M 
Published: March 2009

The Ct parameter has been proposed for characterizing creep crack growth rate in the small scale to extensive creep regimes. In this paper, creep crack growth data from compact specimens ranging in widths from 50.8 to 254 mm and in thickness from 63.5 to 6.3 mm are analyzed to evaluate the Ct parameter. A second objective is to use the load-line deflection rate data obtained during these tests to evaluate the expressions used for estimating Ct in components. These expressions use creep deformation data obtained from uniaxial specimens for estimating Ct.
The analysis of the above data clearly shows that Ct may be used to characterize creep crack growth rate data over a wide range of deformation conditions. For 12.7-mm thick specimens, Ct failed to characterize the creep crack growth rate during the first 1 mm of crack extension. It is further shown that the expressions used for estimating Ct in components are reasonably accurate in the small scale creep region but are not accurate in the extensive creep region. The measured values of load-line deflection rates in the extensive creep region lay between the predicted values based on the assumptions of plane stress and plane strain.
Evaluation of the Relationship Between C*, δ5, and δt during Creep Crack Growth
Authors: Saxena A , Dogan B , Schwalbe K-H 
Published: March 2009

The relationships between C*, δ5 and δt, during creep crack growth are explored analytically and experimentally in this paper. The experimental part of the program used a Cr-Mo-V steel that exhibits a creep-ductile behavior, a Ti-6242Si alloy containing an equiaxed microstructure that is on the borderline of creep-ductile and creep-brittle behavior, and a Ti-6242Si-alloy containing a lamellar microstructure that exhibits an essentially creep-brittle behavior. It is shown that for creep-ductile materials, the rate of creep component of δ5, δ5C, and δt, are essentially similar for crack extensions smaller than 15% of the initial crack size. Either parameter is able to correlate creep crack growth rates in the extensive creep regime in these materials. It is recommended that, for limited amounts of crack extension, δ5C be used as an operational definition of δt, in creep-ductile materials.
For high crack growth rates in the creep-brittle materials, a correlation between da/dt and δ5 is found. However, it is analytically shown that δ5 values are dominated by crack growth under these conditions, therefore, this correlation is not of any significant value and should not be used for structural life predictions.
The Application of a Ductile Fracture Method to Polymer Materials
Authors: Zhou Z , Landes JD 
Published: March 2009

The objective of this paper is to investigate the applicability of an advanced ductile fracture mechanics method to polymeric materials. This method was originally proposed by Ernst and Landes. It has been further developed by the authors and successfully used to predict the behavior of various metallic structural components containing crack-like defects. The inputs needed for this method are calibration functions and fracture toughness. The calibration functions used here are based upon the load separation principle; the fracture toughness is given in terms of the J-R curve. A critical step in the method is the determination of the calibration functions. Two procedures for doing this are introduced in this paper. One is a transformation procedure that can be used to transfer the calibration function for a fracture toughness specimen to one for a structural component. The other is a numerically based one in which the deformation pattern is numerically simulated and the load separation method is applied to define the calibration parameters.
The materials used in this study include two polymers, a toughened nylon and a polycarbonate. The method is used to predict the load versus displacement for a nylon single-edge notched bend specimen and the compact specimens of the polycarbonate. The predictions are compared with the experimental results. It is shown that the ductile fracture method applies to these polymers. However, in the case where the material fracture toughness is strongly dependent on geometry and constraint, accurate prediction can only be ensured when the correct J-R curve is used.
A Sampling of Mechanical Test Automation Methodologies Used in a Basic Research Laboratory
Authors: Hartman GA , Ashbaugh NE , Buchanan DJ 
Published: March 2009

Basic research laboratories typically perform a variety of material tests and obtain the associated data to model material behavior phenomena and develop life prediction methodologies. In this research environment, a mechanical test automation system must meet challenges that are not always present in an industrial testing setting. For example, real-time crack closure load analyses, at the present time, are not widely performed in industrial crack propagation testing. In the research environment, however, on-line crack closure studies are used to make decisions in real-time about changes in test conditions.
A previous paper described the overall system strategy and hardware and one of the crack propagation software modules from the fourth generation of the material analysis and testing environment (MATE) automation system. The present paper discusses selected methodologies that the current (fifth) generation of the MATE system uses to meet the challenges posed while automating research style mechanical tests. The methodologies addressed in this paper include waveform generation and synchronization for cyclic, monotonic, and thermomechanical (TMF) testing as well as specimen damage computation for self-similar cracked geometries.
Spectrum Fatigue Life Assessment of Notched Specimens Using a Fracture Mechanics Based Approach
Authors: Vormwald M , Heuler P , Krae C 
Published: March 2009

Local strain based approaches have been used frequently for the prediction of crack initiation life of notched components. Limitations of the transferability of smooth specimen fatigue data to the notch root as well as cumulative damage problems have been handled by use of fatigue notch factors and consideration of some damage contribution below the fatigue limit. This type of a conventional approach has been applied as a reference case for the present study.
Based on the mechanics of local strain approaches, a model for crack initiation life prediction is outlined. It takes explicitly into account the phenomena related to transferability (size, multiaxiality) as well as a load-sequence dependent damage accumulation. It is based on the closure behavior of short cracks that gives rise to load sequence dependent effective load ranges and continuously decreasing fatigue limits under spectrum loading.
Prediction results are compared to experimental data from notched aluminum 7075-T7351 specimens of various shapes and sizes under both Gaussian and MINITWIST loading. The conventional approach provides unconservative estimates with a broad scatter of life ratios. The fracture mechanics based model gives a relatively low scatter of life ratios around a mean value of unity.
High-Cycle Fatigue of Austenitic (316L) and Ferritic (A508) Steels Under Gaussian Random Loading
Authors: Gauthier J-P , Amzallag C , Le Duff J-A , Diaz E-S 
Published: March 2009

A random loading fatigue test program has been conducted on materials used in pressurized water reactors. The four materials considered were low alloy steels and austenitic stainless steels, including both base metals and associated welds.
The present study concerns crack initiation in the high cycle fatigue domain. Standardized Gaussian stationary sequences were chosen. Both analytical and numerical calculations have been performed in order to determine the parameters necessary for the accurate prediction of fatigue life under random loading.
The general objective of the study is to provide a better knowledge of safety margins taken in the design of nuclear components.
Analysis of results has shown: 1. for the irregularity factor, I = 99% (narrow band spectrum—overall mean stress equal to zero), the calculation of damage is possible using both analytical and numerical methods; and 2. for the other irregularity factors, I ≠ 99% (wide band spectrum—variable mean stress), the damage calculation seems possible using an analytical method or a semianalytical method, but it is difficult to perform.
Numerical calculations have been performed using a rainflow counting method of cycles, the Haigh diagram, constant amplitude S-N curve without fatigue limit, and the linear Miner rule of damage cumulation.
Numerical calculations led to predicted fatigue lives slightly higher than those obtained experimentally, for I = 99% and 70%. This excess of nonconservatism is accentuated in the case of I = 30%, except in the case of the austenitic stainless steel.
Good agreement was observed between damage values obtained using analytical and numerical calculations for the case of I = 99%.
A Software System for the Enhancement of Laboratory Calculations
Authors: Galtier A 
Published: March 2009

The efficiency of a research team is closely related to its ability to take advantage of the results achieved by the scientific community as a whole. The team's ability to manage this documentation, coordinate the knowledge, and harmonize their activities are the factors that lead to success.
The software that is described in this paper has not been completed. However, it can provide a research team with an investigative tool that creates a collective memory, selection procedures, operation modules, and individual or collective work spaces.
Elemental Analysis of Crude and Lubricating Oils by Energy Dispersive X-Ray Fluorescence
Authors: Wheeler BD 
Published: March 2009

Most aspects of petroleum research, exploration, and refining require elemental analysis from trace to minor elemental concentrations. Numerous elements ranging from atomic numbers 15 to 92 can be found in many crudes. Elements such as vanadium, iron, nickel, copper, and arsenic can have deleterious effects on the catalysts utilized in the catalytic cracking process. Other elements purposely introduced as additives into finished lubricating oils must also be measured and controlled. Typically elements such as phosphorus, sulphur, calcium, zinc, and molybdenum are in the range of 0.00 to 5.00 wt%.
In addition to crude oils and finished lubricating oils, engine and turbine bearing wear analysis are often performed by X-ray fluorescence. In these cases, typical bearing and piston ring elements such as copper, chromium, zinc, lead, tin, and silver are usually quantified.
The techniques for preparing samples of crude oil, finished lubricating oils, and used engine oils are basically identical. The sample is transferred into a polypropylene sample cup with a 6.3 μm polypropylene support film. Errors in volume or sample depth can produce significant intensity deviations for higher energy X-rays. The error for lead, for example, is approximately 1.5% relative per 0.1 mL error at volumes of 3 mL. Minimum detectable limits or several tenths of parts per million for atomic numbers 30 to 92 from a range of 5 to 800 parts per million can be expected.
In Vitro Cellular Activation by Fabricated and Clinically Retrieved Bone Cement Wear Particles
Authors: Emmanual J , Emmanual JG , Hedley AK 
Published: March 2009

Bone cement particles were retrieved by enzyme digestion of membranes from revision arthroplasty procedures. These clinically retrieved particles were compared with bone cement particles fabricated in the laboratory using Howmedica's Simplex P bone cement. Three particle sizes, ranging from 230 to 380 μm, of both retrieved and fabricated bone cement were placed in cell cultures, consisting of homogeneous populations of B cells, T cells, macrophages, and fibroblasts. After an incubation of 72 h, the culture supernatant was assessed for levels of interleukin 1 (IL-1) and prostaglandin E2 (PGE2) by an enzyme-linked immunosorbent assay (ELISA) technique.
The fabricated particles showed higher levels of PGE2 in all sizes when compared with the retrieved particles. Fibroblasts showed a significant increase in PGE2 with both retrieved and fabricated particles in comparison with other cell types. There were no differences in IL-1 levels between the fabricated and retrieved bone cement particles.
In this cell culture system, fibroblasts seem to be potent producers of PGE2 secretion, regardless of the shape or size of the particles.
Accommodation of Movement within Building Seals and Sealants for Highrise Tower Architecture and Construction
Authors: Yanoviak AC 
Published: March 2009

This manuscript includes an overview of architectural design research on the subject of cyclical and non-cyclical ‘movement systems’ encountered in the design and construction of highrise building towers. Furthermore, it takes into consideration the need for structural ‘accommodation’ and ‘resistance’ of these multiple movements and ‘movement systems’ in the design, manufacture, application and maintenance of ‘building seals and sealants’.
This presentation includes a basic review of architectural and structural design factors, building codes and standards for the effects of both ‘live load’ and ‘dead load’ on the structural building frame and ‘exterior building envelope’. It also addresses the application of appropriate construction materials and building systems including ‘cladding and glazing systems’. Due consideration is given to the development of design standards and the standard design details required, to accommodate these movements. The accumulative single and multiple effects of wind and seismic forces, as well as gravity and thermal loads are also addressed.
Practical examples of water infiltration problems and inadequate design details, specifications, material applications, waterproofing methods and challenges are noted. References to ‘building seals and sealants’, including the phenomena of ‘curing’, ‘creep’, ‘elongation’, ‘elasticity’, ‘plasticity’, ‘yield limits’, ‘electrolysis’ ‘stress’, ‘strain’, ‘fatigue’, ‘adhesion’, ‘cohesion’, and ‘bonding’, are also presented. Maintenance factors to be considered in remedial repair specifications, design details and installation methods, are also referenced in this manuscript.
Design challenges by architects, developers, and building owners for contractors and manufacturers of ‘building seals and sealants’ are also noted.
Effect of Early Joint Movement on Oxime Silicons Sealants and Comparison to Other One-Part Silicone Systems
Authors: Flackett DR 
Published: March 2009

Two separate investigations are discussed concerning effect of early joint movements. 1. Continuous Cycling While Curing The overall physical properties of sealants cured in a joint undergoing continuous +/- 10% deformation for one week are compared to those of sealants cured under static conditions. Acetoxy, benzamide, alkoxy and oxime systems were studied. 2. “Crack Test” Freshly prepared joints of different formulations were elongated to 25% of their original width starting 15 minutes after preparation. The effect on the surface and body of the sealants as well as the displacement from substrate was observed.
This test, the so called “crack test” was performed on acetoxy, benzamide, alkoxy, amine, and oxime.
Real-Time Measurement of Small-Crack Opening Behavior Using an Interferometric Strain/Displacement Gage
Authors: Sharpe WN , Jira JR , Larsen JM 
Published: March 2009

A procedure for real-time measurement of the opening displacement of small fatigue cracks is reviewed. The method employs a computerized, laser-based, interferometric strain/displacement gage (ISDG) to monitor the relative displacement between two tiny indentations placed across small surface cracks. Complete load versus crack opening displacement curves are obtained for surface cracks of length ranging from 50 μm to several millimetres. The method is applicable to naturally or artificially initiated cracks in smooth or notched specimens. The load-displacement measurements provide a detailed record of crack closure behavior, and estimates of crack size are obtained from measurements of elastic compliance. The resolution of the opening displacement measurements is on the order of 5 nm. Computerization of the system allows measurements to be obtained in real time, facilitating feedback control of testing.
Four versions of the ISDG that are used in different laboratories are described. The instrument's characteristics are presented along with some practical considerations associated with its use. Examples from studies of a number of materials are included to demonstrate applications of the ISDG to the measurement of closure, crack shape, and to automation of small-crack testing.
Measurement of 233U Fission Spectrum-Averaged Cross Sections for Some Threshold Reactions
Authors: Kobayashi K 
Published: March 2009

The 233U fission spectrum-averaged cross sections for twelve threshold reactions were measured relative to the average cross section of 0.688±0.040 mb for the 27Al(n,α)24Na reaction. The reference value was obtained by calculation using the energy dependent cross section in the Japanese Evaluated Nuclear Data Library (JENDL) Dosimetry File and the Watt-type fission spectrum in ENDF/B-VI. General agreement was seen between the measured and the calculated fission-spectrum averaged cross sections. However, there exist discrepancies of more than 10 % between the measured and the calculated average cross sections for the 24Mg(n,p)24Na, 47Ti(n,p)47Sc, and 64Zn(n,p)64Cu reactions. The tendencies in the calculated-to-measured ratios are similar to those for 235U fission spectrum-averaged cross sections we previously measured.
The measured average cross sections were also applied for the spectrum adjustment of the 233U fission neutrons using the Neutron Unfolding Package Code (NEUPAC). The adjusted spectrum is close to the Watt-type fission spectrum of 233U within the uncertainties of the obtained spectrum, although there exist some fluctuations in the ratio spectrum of the adjusted to the Watt-type.
Correlation Between Irradiated and Unirradiated Fracture Toughness of Zr-2.5Nb Pressure Tubes
Authors: Davies PH , Hosbons RR , Griffiths M , Chow CK 
Published: March 2009

Three coordinated research programs were undertaken on the fracture toughness of Zr-2.5Nb pressure tubes to determine relationships between irradiated and unirradiated values, the effect of long-term irradiation, and the causes of the variation in toughness. The present paper describes results from these programs and their implications.
It is shown that a correlation exists between the toughness of the pressure tube material before and after irradiation to a fast-neutron fluence of 1 × 1026 n ∙ m-2 (E &gt; 1 MeV). Further, for the majority of tubes, degradation occurs early in the lifetime of a CANDU reactor; that is, at fluences &lt;2 × 1024 n ∙ m-2. Limited results on relatively low-toughness materials indicate that the flux does not have a major effect on the irradiated toughness and that saturation is complete by about 1.6 × 1025 n ̇ m-2.
The results are discussed in the light of detailed fractographic and microstructural (X-ray diffraction, transmission electron microscopy) studies carried out on the irradiated and unirradiated pressure tube material. It is shown that in the presence of void nucleating sites, such as microsegregated species (chlorine and carbide) and particles (phosphides and carbides), very large reductions in toughness occur with irradiation. In the absence of such species, there is little deterioration in toughness, and the high crack-tip strains (toughness) achieved with unirradiated material can be maintained after irradiation.