bluuebunny/crossref_metadata_2025_split huggingface dataset:
Automation of Autogenous Ignition Equipment
Authors: Lowrie R , Garcia H , Henningson RL 
Published: March 2009

Automation of the AIT equipment for G72 has reduced the operator attendance time during a test from up to two hours to 15 minutes. The testing is controlled by an IBM XT computer operating through an A/D converter board that receives signals from sensors and sends signals to operate valves and switches. The system components were upgraded in oxygen compatibility and pressure rating to allow oxygen pressures to 34.5 MPa (5000 psig).
After sample installation and a leak check, the computer controls the heating rate and records pressure and temperature. Sample ignition is detected as a temperature rise of more than 2°C/s for 5 s. One minute after this is detected, the heater is switched off, and combustion products are purged from the reaction vessel. The test is ended if no reaction is detected when 425°C (800°F) is reached.
The test data are recorded on a hard disk and can be viewed at any later time. Data obtained on several standard materials are very reproducible. Their standard deviations are all less than 2°C.
Reaction Sensitivities of Al-Li Alloys and Alloy 2219 in Mechanical-Impact Tests
Authors: Simon NJ , McColskey JD , Reed RP , Gracia-Salcedo CM 
Published: March 2009

Open-cup and pressurized mechanical impact tests were conducted at White Sands Test Facility (WSTF) on Al-Li alloys (2090, 8090, and WL049) and Al alloy 2219 in various tempers. Pressure, drop height (potential energy), and environment [gaseous (GOX) or liquid (LOX)] oxygen were variables in the test program.
Reactions were detected in all alloys. The reaction sensitivity varied with specimen absorbed energy. Large, macroreactions occurred on specimen shear lips, a region that has very high deformation and is exposed to striker pin-specimen friction. Small microreactions occurred over many areas of the specimen. The effects of the test variables (pressure, drop height, LOX, GOX) on the frequency of macro- and micro-reations are discussed. The energy for fracture is usually less than, or equal to, the energy for (oxygen) reaction.
Temperature Increases in Aluminum Alloys During Mechanical-Impact Tests for Oxygen Compatibility
Authors: Simon NJ , Reed RP 
Published: March 2009

In mechanical-impact testing of Al-Li alloys and Al alloy 2219 for oxygen compatibility, specimens absorb a significant amount of energy in a short time. The absorbed energy is sufficient to crack and, in many cases, produce large fractures (splits) in the specimens. The high strain rate from impact results in the formation of adiabatic shear bands under adiabatic conditions in the deformed areas. Large local temperature increases in the specimens occur during deformation, leading to localized melting.
Estimates of temperature increases assuming macroscopic homogeneous deformation during impact are presented. Characteristic times to propagate a thermal transient and to complete the mechanical deformation process are estimated. The difference between the alloy systems in this characteristic time to propagate a thermal disturbance offers a possible explanation of the differences in sizes and frequencies of reactions observed in Al alloy 2219, compared to the Al-Li alloys.
The History of Pavement Management in the Federal Highway Administration
Authors: Nostrand WA 
Published: March 2009

The paper begins with the results of the authors research into the beginnings of pavement management (PM) and pavement management systems (PMS) in the Federal Highway Administration (FHWA). It continues on through its continued emphasis over the years culminating in the establishment of the Pavement Divisions issuance of a Pavement Policy in January 1989, which includes a mandate that all State highway agencies (SHA) must develop and put into operation a comprehensive PMS within 4 years of the date of issuance of that policy.
The discussion traces PM in the FHWA as it relates to FHWA's program manual (FHPM) and other directives that relate directly to the required activities in SHAs as a condition to receiving Federal-aid. While there have not been many specific mandates to SHAs until this recent one, the FHWA does develop emphasis areas and promote new innovations to the highway community from time-to-time, so it is interesting to relate those initiatives to see how the present requirement came about.
In 1986, the FHWA reorganized to create a Pavement Division. Prior to that there was a Pavement Design Branch consisting of seven people that was part of the Design Division. Today the Pavement Division has 22 people and includes a Pavement Management Branch, which is an indication of the emphasis being placed on pavements and in particularly PMSs.
The FHWA presented an introductory PM training course for State and Federal engineers a considerable number of years ago. There was also a training course for cities and counties labeled “Road Surface Management for local Governments,” which was presented over 30 times and is the fore-runner of an updated course by the same name being offered today. There were several directives regarding the use of PMS which preceded the first FHPM on the subject. Now the FHWA, in cooperation with the Transportation Research Board (TRB) and the American Association of State Highway and Transportation Officials, (AASHTO) is offering an advanced course in PMSs for practitioners.
This paper traces the history, emphasis, pertaining directives, training, and organization with regard to PMS. It concludes with an insight to the future of PMS in FHWA and SHAs.
Implementation of a Pavement Management System for Indiana Airports — A Case History
Authors: Eckrose RA , Reynolds WG 
Published: March 2009

The development of a Statewide Pavement Management System for Indiana airports was a multi-year project. The project has been carefully designed to ensure workability and to capitalize on changes in the state of the art in Pavement Management. The first year was an exploration of the Pavement Condition Index (PCI) inspection procedure. The first twenty eight airports were inspected in 1985, using the PCI procedures as outlined by the Federal Aviation Administration. This first step was unique in that it was the first statewide inspection conducted with the financial assistance of the FAA.
The second phase of the project, covering some twenty airports was conducted in 1986. At this stage, the basic inspection was supplemented with computer software which allowed the state to construct and manipulate Capital Improvement Programs for the pavement systems over a six year planning window.
The project continued in 1989–90 with additional updated PCI inspections at twenty one airports and with the installation of a complete Airport Pavement Management System (APMS) on state computers, which allows the state to update and maintain the system on its own. It also permits the state to conduct in-depth analysis of pavement systems and individual features including forecasts of condition and analysis of maintenance and/or rehabilitation alternatives.
After several years of development and improvement, the State of Indiana now has, in place, a comprehensive APMS which provides a significant decision making tool for planning of needs and capital expenditures for pavement systems for a ten year period.
Development of Optimal Long-Term Network Strategies Using Remaining Service Life
Authors: Kuo W-H , Novak EC , Baladi GY 
Published: March 2009

State Highway Agencies (SHA) develop Maintenance, Rehabilitation and Reconstruction (MR&R) programs every year. These programs may be optimal under some criteria. However, the impacts of these programs on the long-term network condition levels and funding needs are generally unknown. This is because the element of controlling long-term network condition and funding levels is not incorporated into the program development process. This paper presents a Strategy Analysis that uses a Remaining Service Life (RSL) concept to estimate long-term network conditions and funding needs. The characteristics of the strategy analysis are then used to develop optimal long-term network strategies. The procedures for incorporating optimal long-term network strategies into a program development process to develop optimal MR&R programs and at the same time control future network condition and funding levels are also presented.
This strategy analysis method is based on RSL which is obtained from pavement performance curves of condition measurements such as distress index, PSR, ride quality, rut depth,…, etc. It is a generic method because it can be used by any SHA that has established pavement performance curves. The linkage between project and network levels for developing MR&R programs are also discussed.
Influence of the Rheological Properties of Modified Asphalt Binders on the Load Deformation Characteristics of the Binder-Aggregate Mixtures
Authors: Tayebali AA , Goodrich JL , Sousa JB , Monismith CL 
Published: March 2009

While fatigue distress is still of major concern relative to the performance of asphalt pavements, permanent deformation in the form of rutting is assuming more significance for heavy duty highway pavements because of increased number of repetitions of heavy axle loads and increased tire pressures resulting from the use of radial tires (as compared to bias ply tires). In recent years, asphalt modifiers have found increasing use in mitigating excessive permanent deformation in the asphalt concrete pavements. However, questions arise as to what methodology should be used in comparing modifiers and in selecting the amount of modifier which should be used for a particular application.
This paper presents results of a study in which the applicability of dynamic testing is evaluated for assessing rutting potential for mixtures containing modified asphalt binders. Particular emphasis is placed on the rheologic properties of the modified asphalt binders and the binder-aggregate mixtures. Watsonville granite and an AR-2000 California Valley asphalt, and the same asphalt modified with Microfil 8 and K4460 modifiers were used in this investigation.
While the rheologic properties of modified binders may suggest improved performance over the same asphalt in the unmodified state, it is still necessary to define the performance characteristics of the mixture since the aggregate exerts a significant influence on mixture performance.
Mixture stiffness by itself does not appear to provide a measure for assessing the propensity for rutting in mixtures containing modified asphalt binders. Accumulated plastic deformation obtained under dynamic loading seems to represent better, the potential for rutting in mixtures containing modified asphalt binders. These dynamic tests provide results which are sensitive to asphalt type, temperature, degree of compaction and binder content.
Modern Analytical Techniques for Coating and Coating Materials
Authors: Schernau U , Hueser B , Weber K 
Published: March 2009

The past decade has been characterized by an evolution from electronic-regulated to computer-controlled analytical equipment. This holds especially true for spectroscopic instruments, e.g. FT-IR spectrometers and FT-NMR spectrometers, where the application of Fourier transform techniques requires computer support. But Chromatographic instruments are nowadays also equipped with dedicated computers or PCs for controlling the instrument and for data acquisition and evaluation.
The development has led to an improved performance of the instruments in terms of enhanced information, sensitivity, and reliability. These modern analytical instruments can be used favorably for the analysis of coatings and coating materials, making them a valuable tool for the analyst working in this field. In this paper the most important methods will be described and illustrated with examples from daily work.
Since coating materials very often represent complex mixtures, in some cases the combination of different instrumental methods is necessary to obtain the required information. Examples that will be dealt with are pyrolysis-GC/MS and the coupling of Chromatographic and spectroscopic methods, e.g. GPC/FT-IR or GPC/FT-NMR.
In many cases a work-up procedure as a preparatory step prior to the instrumental method is advisable in order to achieve sufficient information. Since many of the coating materials contain saponifiable groups, saponification is still the most prominent method. A general scheme for carrying out such a saponification will be outlined. In addition, we would also like to demonstrate a recently developed method using trimethylsulfonium hydroxide as the reagent. This method, which can be easily applied in the same way as the well-known GC derivatization procedures, yields more reliable results for fatty acids and polyols than the conventional method.
Applications of FTIR to Paint Analysis
Authors: Hartshorn JH 
Published: March 2009

The value of infrared spectroscopy to the coatings industry has long been recognized. Now Fourier transform infrared (FTIR) equipment is replacing dispersive instruments because it is much faster, more accurate, and more sensitive. Of even greater impact is its data processing capabilities. Together, these advances enable the paint analyst to generate information which would have been impossible a few years ago. Applications of this technique to problem solving, cure and weathering studies, and quality control will be reported.
The extraction and identification of minor components and contaminants is one of the most difficult and time-consuming problems for the coatings analyst. The computational power of the FTIR spectrometer permits the point-by-point subtraction of one spectrum from another. The differential spectrum reveals minor differences, which are the other components in the system. This spectral stripping detects constituents which would be difficult, if not impossible, to isolate by chemical means. If the samples are skillfully prepared and subtractions carefully performed, even the concentration can be estimated. Further, the differential spectrum can be identified via computer searching of spectral libraries. This makes problem solving, such as contaminant detection and identification, rapid and effective.
Another difficult task for the coatings chemist is determining the chemical mechanisms of cure, weathering, and degradation. FTIR is providing new, valuable information about these processes. By taking and storing high-precision spectra at frequent, regular intervals, a moving picture of the process can be recorded. We call this technique “Time Lapse IR spectroscopy.” Changes in band intensity are an indication of the chemical reactions taking place within the film. These spectral shifts can be measured quantitatively so that not only the path but also the rate can be determined. Weathering studies are now being carried out after the development of a durable substrate. This provides a useful chemical picture of what is taking place during cure, weathering, or degradation.
FTIR will likely make its greatest contribution to the coatings industry as a quality assurance tool. Du Pont's Finishes Division has developed and deployed a unique instrumental package, called CATS© (Compositional Assurance Testing System). By combining a horizontal attenuated total reflectance (ATR) sampling attachment with a FTIR spectrometer and proprietary software, we have a most effective test for raw materials, intermediates, and finished products. An operator with minimum training can run the spectrum of an incoming material and decide on its acceptability within minutes. If the material is mislabeled or contaminated, it can further be identified and dealt with before a serious problem develops. This eliminates much wasted manufacturing time and material.
Effect of Stress State on the Ductile Fracture Behavior of Large-Scale Specimens
Authors: Roos E , Eisele U , Silcher H 
Published: March 2009

It is well-known from experimental investigations that at specific test conditions and specimen dimensions a sudden fracture, that is, a fracture without or after very confined plastic deformation, can occur even for materials that are characterized by small-specimen results as “tough materials.” This effect usually is defined as a constraint effect without further explanation as to how to describe constraint.
Different constraint definitions were considered originating from theoretical investigations of well-known stress and deformation states of idealized nondamaged structures. As a result of these considerations, the quotient of multiaxiality q is used to analyze the constraint effects on large scale specimens made of steels of different toughness.
It is possible to define a critical q-value as a local fracture criterion. From the location of this qc-value in the ligament of the specimen and from the variation of the q-values in the ligament, it is also possible to assess whether stable crack growth will occur or not.
Quantitative Assessment of the Role of Crack Tip Constraint on Ductile Tearing
Authors: Brocks W , Schmitt W 
Published: March 2009

The quantities describing constraint and triaxiality and their relation with each other are discussed for various loading conditions and specimen geometries by comparing numerical simulations of crack growth based on the J-integral concept and on micromechanical damage models with the corresponding experiments.
It is shown that the “geometry dependence” of JR-curves is a natural feature due to different patterns of plastic flow and micromechanical processes depending on the local stress state. Hence, this dependence cannot and should not be overcome by manipulating the definition of J. A pragmatic definition of a local triaxiality parameter is given that gives reliable and reproducible results. A linear relationship is found between the triaxiality and the tearing modulus of various specimens of the same material.
Energy Dissipation Rate and Crack Opening Angle Analyses of Fully Plastic Ductile Tearing
Authors: Turner CE , Braga L 
Published: March 2009

The effects of geometry on the JR-curve for ductile tearing toughness of a titanium alloy are investigated in a series of notch bend tests taken to large amounts of growth in the fully plastic regime. For this material there is a remarkably small effect of thickness over a nine-fold range from 4 to 35 mm, but for thicknesses of 17.5 mm and greater, the R-curves are lower for wider specimens. The results are then analyzed in terms of energy dissipation rate and crack opening angle. Both terms fall rapidly just after initiation and pass to a near steady-state regime after about 10% growth. In steady-state tearing the crack opening angle is substantially constant with growth, while the steady-state dissipation rate can be split into areal and volumetric components.
It is concluded that stable ductile tearing of this material at limit load conditions is controlled by processes of plastic deformation that, if expressed as conventional R-curves, show a definite dependence on width. However, interpretation by either crack opening angle or dissipation rate model is sensitive to how the data are analyzed. The dependence of the models on the degree of plane stress or plane strain is not yet clear so that extrapolation to other sizes of specimens is still uncertain.
Predictions of Specimen Size Dependence on Fracture Toughness for Cleavage and Ductile Tearing
Authors: Anderson TL , Vanaparthy NMR , Dodds RH 
Published: March 2009

A framework for predicting the effect of crack-tip triaxiality on fracture toughness is outlined. This methodology is a two-parameter approach that considers the micromechanism of failure. A local damage parameter is used in conjunction with a crack-tip stress analysis to predict the effect of specimen dimensions on toughness. In the case of cleavage fracture, the local criterion involves the maximum principal normal stress, σ1 as well as the volume over which σ1 acts. The agreement between predictions and experimental data is very good in this case. for initiation of ductile tearing, we defined a damage parameter based on a modified version of the Rice and Tracey hole growth model. The analysis indicates that ductile fracture is less sensitive than cleavage to triaxiality. While this result is broadly consistent with experimental observations, further work is necessary to develop improved local criteria for ductile fracture.
The micromechanics approach proposed by the authors was compared with two-parameter fracture mechanics methodologies based on continuum theory, such as the K-T and J-Q approaches. These continuum methodologies, which involve two-term expansions of the crack tip fields, are descriptive rather than predictive. That is, these approaches describe the crack tip triaxiality, but they do not predict the effect of triaxiality on fracture behavior. The micromechanics approach, however, was developed for the purpose of making such predictions. Thus, the continuum and micromechanics approaches to two-parameter fracture mechanics are complementary.
Mechanical Properties of Immature Callus in Long Bones
Authors: Miyasaka Y , Ohyama M , Sakurai M , Yokobori AT , Sasaki S 
Published: March 2009

Callus distraction had long been believed to be harmful to fracture healing until the development of a new method named callotasis, which gave the green light to the field of long bone lengthening. This revolutionary method showed that the distraction does not disturb bone formation, which was confirmed by our results of clinical cases. One of our callotasis cases was presented to show its characteristic X-ray features in the course of callotasis.
We made experimental callotasis in rabbit femurs and performed mechanical tests for callus of the bones in order to investigate its mechanical behavior when tensile loads were applied. Femurs of eight rabbits were osteotomized at the level of the midshaft with a bone saw and fixed with a mini-model external fixator. Gradual callus distraction was performed at the rate of about 0.7 mm per day. The femurs were removed after sacrifice and served as bone specimens for the mechanical tests. Control long bones were twelve osteotomized femurs fixed with the same external fixator without callotasis and ten osteotomized tibiae fixed with an intramedullary Kirschner wire.
This immature callus showed the characteristics of hysteresis in the load-deformation curves and also those of stress relaxation in stress relaxation test. We conclude that the callus in callotasis has the property of viscoelasticity, and infer that this property is one of the mechanical bases making callotasis possible.
Evaluation of Mechanical Properties of Metallic Biomaterials
Authors: Higo Y , Tomita T 
Published: March 2009

In this paper, some methods for evaluating the properties of metallic biomaterials are proposed and discussed, with special interest in the requirements of biomaterials which strongly relate to corrosive properties. A simple evaluation method for determining metallic elution was proposed, and the results are shown.
The most important mechanical property of a biomaterial is the fatigue life under consideration of actual usage and environment. The methods employed for the artificial joint were used as an example. The appropriate fatigue test for the biomaterial component is a four-point side notch bend specimen and the dimensions of the specimen are given. The notch tip radius of curvature should be the smallest radius of curvature of the implant design. The notch tip surface finishing condition should especially be examined, because not only notch radius (stress concentration) but also notch surface condition (scratch and structure sensitivity) affect the fatigue properties. The corrosion characteristics of biomaterials are also estimated by measuring the difference of the fatigue life in a laboratory air environment to that in a physiological saline solution environment. The details of the results on pure titanium, titanium alloy, and stainless steel are given.