bluuebunny/crossref_metadata_2025 huggingface dataset:
A Computerized Variable Amplitude Fatigue Crack Growth Rate Test Control System
Authors: Joyce JA , Wright W
Published: March 2009

The objective of this paper is to present a low cost control system for servohydraulic load frames to perform variable amplitude fatigue crack growth rate testing. The system consists of a relatively low cost personal computer equipped with two combination 12 bit A/D-D/A cards. A four channel simultaneous A/D card is used for reading load and CMOD from the specimen while a second card provides real-time function generation of the command signal. Depending on the loads and specimen size, variable amplitude loading can be applied at high speeds of up to 100 Hz, thereby minimizing the time required for threshold type testing. This system can be connected easily to existing hydraulic equipment and will provide variable amplitude capability that is both low in cost and flexible enough to perform specialized testing.

The system is capable of automatically shedding loads under both constant R-ratio and constant Kmax conditions, and could be adapted easily to other specialized types of testing. Both crack length and ΔK are calculated continuously using the compliance of the specimen. In addition, crack closure analysis is performed from the compliance data to calculate ΔKeff. The results of tests performed on high strength-low alloy structural steel used for highway bridge construction are presented to demonstrate the capabilities of the system.
Fatigue Life Prediction Under Periodical or Random Multiaxial Stress States
Authors: Robert J-L , Fogue M , Bahuaud J
Published: March 2009

A fatigue life prediction method suitable for multiaxial stress states and constant amplitude or random loading is developed. In the case of random loading, a suitable counting variable is proposed so that the rainflow counting method can be applied in order to extract cycles. A multiaxial fatigue life criterion is used to define the damage corresponding to each cycle. This criterion is based on the quadratic mean value of a damage indicator over all the planes through the point where the fatigue life calculation is made. The validation of this criterion is made with periodical multiaxial fatigue test results. Miner's rule is used for the cumulation of the damage. The whole fatigue life of the component is evaluated in terms of the number of repetitions of the loading block.
Load Simulation Test System for Agricultural Tractors
Authors: Nishizaki K
Published: March 2009

To establish an evaluation technology on the reliability for agricultural tractors, we have developed a field simulation system to evaluate the durability of agricultural tractors.

The load simulation system for the power take-off (PTO) shaft and the road (road-load) simulation system utilizing the “remote parameter control” principle are described.

First, experimental studies on the PTO load simulation system prove the possibility of laboratory simulation by using actual loads. This system includes the analysis of torque and revolution data frequency and the modification (editing) of the load pattern (actual data).

Second, experimental studies on the road-load simulation prove that with the utilization of the “remote parameter control” method it is possible to obtain excellent results when working with a servohydraulic test system. Some factors that affect the simulation processes, which are different for different tractors, are also shown.
Applying Contemporary Life Assessment Techniques to the Evaluation of Urban Bus Structures
Authors: de Freitas MM , Maia NM , Montalvão e Silva J , Silva JD
Published: March 2009

The authors present a study where personal computers are used to analyze the structural behavior of urban buses and to obtain in-service loading histories. Theoretical analysis, previously performed and based on finite element techniques and static loads, allowed the correct choice of ten points, in a typical bus structure, where strain gages were bonded to measure the strain history under real working conditions. The measured data were analyzed using the rainflow counting method to obtain the characteristic loading and generate a typical service spectrum for a bus structure. Results for ground transport vehicles were found to be similar to those obtained by other authors. The fatigue crack growth behavior of the steel used in the bus structures under analysis was determined experimentally and the data thus obtained were used to calculate the fatigue crack growth behavior of the bus structural elements. Finally, the fatigue life of these elements, due to the loading spectrum previously obtained, was predicted using a computer-aided fatigue crack growth calculation based on Forman's law of crack propagation.
Fatigue and Fracture Analysis of Type 316L Thin-Walled Piping for Heavy Water Reactors: Crack Growth Prediction Over 60 Years (With and Without Stratification) and Flawed Pipe Testing
Authors: Poole AB
Published: March 2009

Thermal stresses in piping produce through-wall stress gradients that may influence crack growth in the pipe wall. In heavy water reactors (HWRs), the pressure-induced stress in piping is small due to the low pressure values. For major HWR plant transients, the thermal stresses (both wall profile and bending due to axial thermal growth) provide approximately 80% of the nominal pipe stress. Cases of local thermal stratification can provide a significant increase in the pipe stresses and the number of stress cycles applied to the piping. One focus in this paper will be to assess the impact of thermal stresses, in general, and thermal stratification, in particular, on the growth of flaws in a pipe due to fatigue loadings. The study will evaluate both the primary loop piping and the pressurizer surgeline piping. Evaluations of fatigue crack growth will be developed for both base material and weldments. The crack growth analysis for 60-year operation of a HWR plant will be reviewed. This analysis will be provided for the primary loop piping and the pressurizer surgeline piping and will establish the worst-case flaw size predicted from fatigue analysis by end of life.

Full-scale flawed pipe fracture testing has been completed at the Oak Ridge National Laboratory (ORNL) in an approach to show the improbability of an instantaneous double-ended-guillotine break (DEGB) for HWR primary piping. This testing required a major facility (Pipe Impact Test Facility, PITF) to apply all possible design loads, including an equivalent major earthquake (called the SSE earthquake). The facility was designed and built at ORNL in six months. The test article, a 6.1-m (20-ft) long, 406-mm (16-in.) diameter, Schedule 40, 316 L Type stainless steel pipe was fabricated to exacting standards and inspections following the nuclear industry standard practices. A flaw was machined and fatigued into the pipe at a butt weld as an initial condition. The flaw/crack was sized to be beyond the worst-case flaw that HWR piping could see in 60 years of service—if all leak detection systems and if all crack inspection systems failed to notice the flaw's existence.

Since October 1991, the test article was subjected to considerable overloadings. The pipe was impacted 104 times at levels equal to and well beyond the safe-shutdown earthquake (SSE) loadings. In addition, 569 751 fatigue cycles and 20 purposeful static overloads have been applied in order to extend the flaw to establish the data necessary to confirm fracture mechanics theories, and, more importantly, to simply demonstrate that an instantaneous DEGB is highly improbable for a HWR primary system at an operating pressure of 1.72 MPa and temperature of 110°C.
A Rule-Based System for Estimating High-Temperature Fatigue Life
Authors: Bonacuse PJ
Published: March 2009

A rule-based expert system for high-temperature fatigue life estimation (HTF) is currently under development. This system will augment a designer's ability to make preliminary engineering decisions on the durability of high-temperature components. It may also be used as a verification tool, to establish bounds for fatigue life estimates performed using other, perhaps more sophisticated, methods. The system uses an expert system shell (C Language Production System—CLIPS). The rules in the system select appropriate fatigue life models based on the available material properties and the application. The rules and functions in the HTF system incorporate materials property data (sufficient for the fatigue life models used) for a small group of aerospace materials. If the system cannot find the user-specified material in the rule base, the user is queried for the materials property data. The program calculates (or approximates) the required fatigue life model parameters and performs the appropriate life calculation. The lower bound on the predicted life, based on the estimated error in the material properties, boundary condition data, and on experience with the fatigue life model, is determined via a direct Monte Carlo simulation. Fatigue life models incorporated into the system make allowances for the influence of multiaxial stress/strain states and creep-fatigue-environment interactions. The scope of this project is limited to alloys used in high-temperature, high mechanical/thermal stress applications.
Optimum Fracture Control Plan for Gas Turbine Engine Components
Authors: Lassen T
Published: March 2009

This paper describes a probabilistic damage tolerance concept for the fatigue damage in gas turbine engine components. The statistical scatter in time to crack initiation is considered using a Weibull distribution, while the stochastic crack growth is treated by a Markov chain approximation. The approximation is a unit-jump discrete state/discrete time Markov chain where damage states are related to the fatigue crack depths. The model parameters are estimated from experimental statistics and a linear fracture mechanics simulation of the fatigue propagation. The effect of in-service inspection is considered by the use of Bayesian updating techniques. The analysis verifies that it is possible to extend the service life and maintain the fatigue reliability of critical components by an appropriate periodic inspection program.
Prediction of the Fatigue Life of Mechanical Structures
Authors: Flavenot J-F
Published: March 2009

Methods for analyzing service time histories and simulating fatigue conditions are now well known and incorporated into application software. However, they carry a risk, if used routinely, that the effects of interaction of the material, the fatigue loading conditions, and the structural design are often too complex for correct evaluation using a single method of approach.

The first part of this paper presents the different phases that must be included in the methodology for predicting service fatigue life and recommends any steps in which the analysis parameters (significant amplitude level of maximum cycles or nondamaging cycles, choice of low- and high-truncation levels of the spectrum, choice of counting method, etc.) may be in contradiction with the real damage process of the material.

After determining the correct loading history, different ways of predicting fatigue life using two methods are presented, namely, 1. the use of damage laws for predicting the crack initiation life (or the damage tolerance approach with modeling of crack propagation), and 2. simulation of the loading history on a fatigue machine. The methodology used in this approach is presented together with precautions to be taken. These two methods are explained, along with the importance of the interaction of the material properties, the fatigue loading, and the design.
Fatigue Testing and Life Prediction for Notched Specimens of 2024 and 7010 Alloys Subjected to Aeronautical Spectra
Authors: Bleuzen C , Chaudonneret M , Farcy L , Flavenot J-F , Ranganathan N
Published: March 2009

Tension compression fatigue tests were carried out on notched specimens made of aluminum Alloys 2024 and 7010. For Alloy 2024, the specimens were submitted to an aeronautical spectrum developed from a transport aircraft spectrum using different percentages of low-level cycle omission (omission of cycles as a function of the mean stress). For Alloy 7010, a landing gear load spectrum was used. Other tests were carried out with simplified loading sequences in order to study the influence of under- or over-stressing on the fatigue damage. The experimental fatigue life up to crack initiation was measured using the electrical potential drop method (crack initiation on the order of 0.1 to 0.4 mm). Tests were also carried out in order to determine the fatigue properties of the materials tested.

Three methods of fatigue life prediction were tested. In the first method, developed by Office National d'Etudes et de Recherches Açrospataics (ONERA), the notch effect was taken into account using the Neuber calculation and the fatigue damage was calculated using a nonlinear damage accumulation law (Lemaitre-Chaboche). The two other methods consist of using the local strain life approach with Fatimas software or Glinka's method that takes the notch aspect into account using the Neuber calculation and the fatigue damage calculation using Miner's law.

A comparison of the results obtained using these three methods of fatigue life prediction shows that a better prediction is obtained when a nonlinear damage accumulation law is used. Nevertheless, it can be noted that the three different methods used in the study often give a nonconservative prediction of the fatigue life.
Thermal-Mechanical Fatigue Testing
Authors: Koster A , Fleury E , Vasseur E , Remy L
Published: March 2009

The development of thermal-mechanical fatigue (TMF) facilities over nine years is described. This test is aimed at simulating the behavior of a volume element of a real component under non-isothermal conditions. The present facilities were set up to simulate thermal fatigue loading of nozzle guide vanes and blades in gas turbines. Adequate accuracy and versatility were obtained in the first TMF facility using conventional low-cycle fatigue equipment for high temperature testing and an Apple IIe microcomputer. The capability and limitations of this first facility are described. A second improved facility was then set up, and the performance was improved by the use of a Macintosh with an advanced software package.
Measurement of Transformation Strain During Fatigue Testing
Authors: Neu RW , Sehitoglu H
Published: March 2009

Dimensional changes from stress-induced transformations simultaneously influence the fatigue behavior, while thermal-induced transformations do not. These dimensional changes, including the anisotropy, are measured in the laboratory under various loading conditions. This technique can be used to determine the best balance between materials with good dimensional stability as well as good fatigue resistance. Axial strain-controlled monotonic and fatigue test results for different treatments of 4320 steel, both carburized and plain, tested at temperatures from -40°C to 255°C are discussed. Upon increase in volume, due to the stressinduced phase transformation in the carburized steel containing 35% retained austenite, a mean compressive stress developed, improving the fatigue life by a factor of 10. However, this steel was also the least dimensionally stable. A liquid nitrogen treatment reduced the amount of retained austenite to 14%, which made the steel more dimensionally stable, but decreased the fatigue life.
Advances in Test Methods to Assess the Long-Term Performance of Sealants
Authors: Lacasse MA
Published: March 2009

In this review, a number of aspects related to sealant testing and evaluation will be addressed. Those factors that are most important in determining the useful life of sealants, as well as the choice of the most appropriate test methods to assess their performance are discussed. Some of the topics that are treated include, for example, studies undertaken to determine the amount and rate at which building joints move and their significance in relation to the effect of movement rate on the mechanical properties of sealants; the relevance of the failure envelope in evaluating the performance of sealants; the effect of daily cycling on the extended sealant; the use of strain-cycling movement when predicting sealant performance; the significance of light and moisture on the overall degradation of the sealant; the importance of movement in the deterioration of sealants joints. The nature of future research regarding the long-term performance of sealants is identified.
The Relation Between Rheology, Artificial Weathering, and Urethane Sealant Performance
Authors: Leonard NE , Malik TM
Published: March 2009

There has been vigorous debate on the ability of urethane sealants to withstand the conditions found in high-performance construction applications. A number of studies have suggested that multicomponent urethanes, as a generic technology, are unable to endure the high heat, humidity and ultraviolet light found in some parts of the world.

This paper argues that it is incorrect to make blanket statements about the performance characteristics of any sealant technology, whether it is silicone or organic. The focus is, however, on multicomponent urethanes. Results of standard ASTM xenon and QUV tests are discussed. Several novel test regimens, including the “frog pond test” and sophisticated Theological techniques, are also reviewed. To gather as much data as possible, samples were run through these procedures for as long as 7000 hours.

This paper outlines several important conclusions. First, silicones actually have a higher modulus at cold temperatures (below -35°C) than the multicomponent urethanes examined. Second, the wide range of performance results in the urethanes tested highlights the fallacy of blanket statements about these sealants. Some were clearly unable to endure the conditions to which they were exposed. Other multicomponents, however, did not degrade. Rheological techniques are used to augment the data provided by the traditional QUV and xenon procedures.
Case Histories of Successfully Sealed Expansion Joints with Polysulfide Sealants
Authors: Fiorillo AR
Published: March 2009

Polysulfide polymers have been used as the base polymer in elastomeric sealants for over 40 years. This paper will discuss some of these applications and will show the versatility of these sealants to perform well in various environments.
Sealant Selection Using an Expert System
Authors: Lacasse MA , Beznaczuk LM , Gowri K
Published: March 2009

Sealants used on the exterior of the building envelope must fulfill their performance requirements in a very demanding location within the enclosure system, namely joints. For this reason they tend to be prone to premature failure if not properly matched to the surrounding conditions and materials. Sealant selection is a complex and time-consuming process involving the simultaneous consideration of a multitude of performance criteria. A systematic approach that enables a more comprehensive consideration of the various criteria is therefore important. The prototype expert systems are an attempt to do this. In this paper, a review is made of the main features of the initial prototype sealant selection expert system, including a brief discussion of the decision making process, the assumptions and inherent limitations of the system. Of particular interest in this paper is a description of the advanced prototype system being developed which provides significant improvements over the initial system. This advanced system will include an extensive database from which the following information can be extracted: weather data, sealant performance data, and graphic details database on sealant application.
Strength Evaluations of Bridges
Authors: Tharmabala T
Published: March 2009

This paper describes the various characteristics of a bridge structure to be considered in the strength evaluation of a bridge structure. A brief summary of load test results on various types of bridge structures are given. Some examples of bridge failures are described. Strength evaluations of bridges are described by selected example cases.
Performance of Bridge Deck Concrete Overlays
Authors: Babaei K , Hawkins NM
Published: March 2009

This paper documents performance of twelve concrete bridge decks in Washington State that were rehabilitated and/or protected with latex-modified concrete and low-slump dense concrete overlays in order to prevent further deicing salt penetration and concrete deterioration caused by reinforcing steel corrosion. An evaluation is made of the factors that have affected the serviceability of those overlaid bridge decks, and recommendations are made based on that evaluation for the design and construction of concrete overlays in order to improve bridge deck performance and to extend bridge deck service life. The factors evaluated are overlay freeze-thaw scaling, surface wear and skid resistance, surface cracking, bond with the underlying deck, chloride and water intrusion, and finally the concrete overlay's ability to retard continued reinforcing steel corrosion and corresponding concrete deterioration.

The results of the evaluation indicate that, regardless of concrete deterioration caused by reinforcing steel corrosion, concrete overlaid bridge decks will require resurfacing after about 25 years of service. That maintenance will be needed as a result of traffic action and weathering. Typical forms of distress are freeze-thaw scaling, extensive wear in wheel lines, lack of skid resistance, and the loss of overlay bond. Concrete overlays are resistant but not impermeable to chloride infiltration. Further contamination of the underlying deck occurs in time depending on the rate of salt application. There are indications that the continued corrosion of reinforcing steel in the salt-contaminated underlying deck is less extensive in the absence of overlay surface cracking. There are numerous reasons for concrete overlays cracking during construction and service, and those reasons and their relation to the performance of bridge decks is discussed.
Orthotropic Steel Plates for Bridge Deck Replacement
Authors: Stahl FL
Published: March 2009

A large number of our nation's bridges have reached the age where serious deterioration requires replacement of the roadway deck. Where first cost is the determining factor, replacement in kind—usually reinforced concrete—is the normally accepted method. However, where life cycle costs are considered, or where availability of traffic capacity during commuting hours is important, orthotropic steel deck construction offers a practical solution.

Orthotropic deck construction consists of a steel plate stiffened by single web (open) or double web (closed) ribs and paved—usually prior to installation—with a layer of asphalt. In a typical application, a section of the old deck is cut and removed during low-density traffic hours and immediately replaced by a modular section of new orthotropic deck. As soon as this section is connected to the supporting framework, it can be opened to traffic without restrictions. Several such decks have been installed recently on major bridge structures, similar in principle but quite different in details and execution.
A Review of Modern Instrumental Methods of Elemental Analysis of Petroleum Related Material: Part II—Analytical Techniques
Authors: Nadkarni RA
Published: March 2009

A review is presented of the state of the art in elemental analysis of petroleumrelated materials (crude oil, gasoline, additives, and lubricants) using modern instrumental analysis techniques. The major instrumental techniques used for elemental analysis of petroleum products include atomic absorption spectrometry (both with flame and with graphite furnace atomizer), inductively coupled plasma atomic emission spectrometry, ion chromatography, microelemental methods, neutron activation, spark source mass spectrometry, and X-ray fluorescence. Each of these techniques is compared for its advantages, disadvantages, and typical applications in the petroleum field.
Analysis of Additive Metals in Lubricating Oils
Authors: Mackey JR , Watt ST , Cardy CA , Smith SI , Meunier CA
Published: March 2009

Additive elements such as Ba, Ca, Zn, Cu, Cl, P and Mg are added to lubricating oils for improved engine performance. Although necessary, additive concentrates are very expensive and it is important that refineries blend within the required specifications using reliable and accurate analytical techniques to measure the metal concentrations.

This paper is an overview of additive element analysis in lubricating oils at the Esso Petroleum Canada Research Centre. A comparison of the two current techniques, wavelength dispersive X-ray fluorescence (WXRF) and simultaneous inductively coupled plasma emission spectroscopy (ICPES), will be described.

We will give a brief summary on the scope, theory, and methodology of each technique plus the strengths and weaknesses of each method as they relate to fresh and used oils. A comparison of the precision between WXRF and ICPES will be examined as well as the use of robotics to improve precision and turnaround time with the ICPES method.

Our hope is to give the nonexpert a better understanding of the advantages and disadvantages of WXRF versus ICPES when choosing instrumentation or methodology for analyzing additive elements in fresh and used lubricating oils.
Methods Development for Trace Metal Characterization of Crude Oil by Inductively Coupled Plasma Atomic Emission Spectroscopy
Authors: Gonzales M , Lynch AW
Published: March 2009

Metals and other contaminating elements found in low concentrations (10 ppm or less) in crude oil can alter the conversion of refinery feedstocks by poisoning catalysts. Organic matrices, such as crude oil, can cause complications when analyzing for trace elements by inductively coupled plasma atomic emission spectroscopy (ICP-AES). This study addresses some of the problems associated with direct analysis of P, Mo, Zn, Pb, Ni, Sn, Fe, Cr, V, Ca, Cu, Ti, Ba, As, Hg, Se, Sb, and Mg in crude oil using this technique. Specific areas addressed were solvent selectivity, spectral overlap, and the use of an internal standard to overcome sample inconsistencies such as viscosity. Kerosine was selected, instead of xylene or MIBK, as the best solvent based on a study of detection limits. A list of preferred wavelengths, included in the report, is based upon a scanning study that determined spectral overlap and sensitivity. The use of scandium as an internal standard overcomes delivery and nebulization problems associated with variations in viscosity and also drift in the instrument. Recovery experiments on crude oil samples containing known amounts of the elements of interest show greater than 90% recovery on 14 of the 18 elements listed.
Analysis of Lubricant Additive Elements by X-Ray Fluorescence and Supporting Methods
Authors: Sieber JR , Salmon SG , Williams MC
Published: March 2009

At Texaco's Research Center, X-ray Fluorescence (XRF) is our workhorse method for the determination of additive elements in lubricating materials. Other analysis techniques are used to assist in method development by confirming compositions of standards and quality control samples, or by verifying analysis results from newly developed XRF methods.

Often it is impractical to make a determination of all analytes in a sample by XRF due to inherent limitations of X-ray fluorescence measurements and the complexity of calibrating for many analytes in a single method. Analyses of high volumes of samples can be made more efficient by omitting difficult or infrequently encountered elements. When a unique sample comes along, alternative analytical techniques are used to determine elements for which the X-ray spectrometer is not sensitive or not calibrated. These concentrations can be combined with theoretical influence coefficients to correct existing XRF calibrations for the effects of unanalyzed elements. A working example, sodium in research samples, is given. Another example, barium in oils, shows the serious shortcomings of this approach. Alternative techniques such as inductively coupled plasma atomic emission spectroscopy, atomic absorption spectrometry, sulfur determination by high temperature combustion with infrared detection, and wet chemical methods can be used to complete an analysis or to confirm the accuracy of XRF methods for determinations of additive elements in lubricants. Examples of our elemental analysis methods, how they relate to ASTM procedures, and how we use our techniques are described.
Application of X-Ray Tomography to the Nondestructive Testing of High-Performance Polymer Composites
Authors: Bathias C , Cagnasso A
Published: March 2009

In this paper we show how it is possible to use a medical scanner to study damage inside polymer composites reinforced by long fibers. Several examples including compression damage, tension damage, and impact damage are given for glass fiber and carbon fiber reinforced polymer composites. Most of the internal damage can be observed using X-ray tomography.
Application of NDE Data to Finite Element Analysis of Parts Containing Defects
Authors: Frankle RS
Published: March 2009

Failure Analysis Associates®, Inc. (FaAA) has developed software that permits digital nondestructive evaluation (NDE) data to be input to finite element analysis. The code currently accepts input from X-ray computed tomography (CT) and digital ultrasonic inspections. Parameters measured nondestructively, such as CT density and ultrasonic attenuation, are automatically assigned to the integration points of a three-dimensional finite element model at the same spatial locations as in the actual part. These parameters are then used to modify the material properties input to the analysis in order to characterize anomalies in a part. FaAA successfully employed the code to analyze carbon-carbon cylinders containing intentional defects. The results of the analysis demonstrate the operation and application of the code. This approach to analysis of parts containing defects can form the basis of a system for automated and quantitative evaluation of anomalous parts.
Dynamic Mechanical Analysis as a Complementary Damage Characterization Technique for Composite Materials
Authors: Osiroff R , Stinchcomb WW
Published: March 2009

The applicability of mechanical spectroscopy as a potential complementary technique to characterize damage and fatigue response of fiber-reinforced laminates was investigated. The interaction between damage induced by cyclic mechanical loads and time-dependent behavior was examined [1,2]. The magnitude and nature of the damage and mechanical response were evaluated.

The effects of fatigue damage on the time, temperature, and frequency response of fiber-reinforced laminates were measured by performing dynamic mechanical analysis (DMA) tests on composite coupons which had been subjected to different amounts of fatigue loading and which exhibit varying degrees of fatigue-induced damage. Creep tests at different temperatures were conducted. Frequency multiplexing was accomplished over a temperature range encompassing the glass transition temperature. The effects of frequency on the temperature transitions of the loss and storage moduli were observed.

The DMA test results were interpreted in light of other conventional measures of fatigue response, such as change in dynamic stiffness and residual strength, and compared to nondestructive evaluation data of the different damage modes present in the laminates.

This paper includes a discussion of the applicability of DMA as a potential test methodology to investigate the effects of fatigue-induced damage on the viscoelastic behavior of fiber-reinforced laminates.
Ultrasonic Detection of Fatigue Damage in Glass-Epoxy Composite Flywheels
Authors: Simpson WA , McClung RW
Published: March 2009

Energy storage flywheels fabricated of S2 glass-epoxy composite were studied to determine the behavior of the ultrasonic properties as a function of strain history and to identify possible predictors of incipient failure. Tension specimens of the flywheel material were loaded uniaxially, and the ultrasonic properties (that is, the shear and longitudinal wave velocities and the attenuation) were measured as a function of strain. Finished flywheels were similarly tested at various stages during cyclic spin testing; in addition, the polar backscattering intensity as a function of fatigue cycle was recorded. The velocities are excellent indicators of the maximum strain incurred at each point of the flywheel, and the attenuation delineates the region in which the stress is high enough to initiate microcracking in the matrix.
Time-Temperature Indicators as Food Quality Monitors
Authors: Taoukis PS , Labuza TP , Francis RC
Published: March 2009

This paper summarizes the benefits that can be obtained by the use of time temperature indicators (TTI) as monitors of quality in the food distribution chain and the requirements for their successful application. Modeling of the TTI response characteristics based on kinetic principles and the Arrhenius equation allows the estimation of the quality level of the food from the response of the attached TTI. The factors that define the reliability of the TTI under variable temperature exposure are analyzed.
Packaging for the 90's: Convenience Versus Shelf Stability or Seal Peelability Versus Seal Durability
Authors: Matty JT , Stevenson JA , Stanton SA
Published: March 2009

As the popularity of shelf-stable convenience foods increases, there is an emerging need to develop reliable, polymer-based food packages with peelable, heat-sealed lids for foods packaged under hot-fill, aseptic, or retort processes. For these products, seal integrity and package durability are critical to product safety and consumer acceptance. These concerns, in conjunction with the need to provide the convenience of peelable lids, give rise to the challenge of evaluating various aspects of package performance influencing seal integrity, durability, and peelability. Proper evaluation of these parameters requires testing techniques that yield data that are indicative of the attribute under consideration. The results of these tests, along with some fundamental understanding of mechanical and chemical properties of the materials being used, are key factors for measuring the performance of the package “system.” Today, there are a variety of proprietary procedures for evaluating critical aspects of package performance. The plethora of test methods needs to coalesce into a set of standardized procedures that can be used to provide meaningful product performance data communicated in a common language that can be utilized and understood by all of the diverse groups involved in taking a packaging “system” from a concept to the grocery shelf. This need is critical in markets where issues such as consumer safety and liability risks are major factors influencing packaging acceptance.

This presentation provides a detailed review of techniques and equipment developed for easy-to-use, reproducible, standardized procedures to evaluate the performance of polymer-based food packages. It also discusses test results and their relationship to package performance. The discussion will focus on test methods, including equipment and instrumentation, applicable to: 1. Container seal integrity. 2. Lid peelability. 3. Container abuse resistance.

Normalized test data are used to supplement the discussion of the procedures utilized. The impact of fundamental specimen properties, instrument response limitations, and other factors influencing the results will also be reviewed.
Debris-Mediated Osteolysis—A Cascade Phenomenon Involving Motion, Wear, Particulates, Macrophage Induction, and Bone Lysis
Authors: Clarke IC , Campbell P , Kossovsky N
Published: March 2009

The spectrum of effects leading to the bone loss observed around failing implants is explained by means of a wear-debris-activated, macrophagic osteolytic mechanism. This concept is presented as the universal failure mechanism for all arthroplasty components, irrespective of fixation mode. The early descriptions of this bone-destruction process can be traced back to various clinical reports in the early 1950s which described failure of polymeric hemiarthroplasty implants, such as nylon and polyethylene cup arthroplasties, and the early polymethyl methacrylate, short-stem, Judet implants. Thus, polymeric debris and macrophages appear to be particularly reactive agents in the bone lysis phenomenon seen around contemporary total hip designs, but any particulate material small enough to be phagocytosed may contribute to this mechanism (metallics or ceramics). In addition to wear at the articulating surfaces, micromotion at any interface also has the potential to produce wear particles, thereby adding to the osteolytic process. Thus, the three potential sources of wear debris in contemporary total joints are (1) metal/ultrahigh-molecular-weight polyethylene (UHMWPE) joint articulation, (2) implant/coating interfaces, and (3) implant/bone interfaces. Present and future designs of joint replacement components must emphasize material and design combinations that will reduce the incidence of debris formation. Such designs will extend the survival time of the implant and also preserve bone stock in the eventuality that revision becomes necessary.
Endosteal Osteolysis Around Well-Fixed Porous-Coated Cementless Femoral Components
Authors: Jasty M , Maloney WJ , Harris WH , Galante JO , Callaghan JJ
Published: March 2009

Seventeen cases of focal endosteal femoral osteolysis around cementless porouscoated femoral components of total hip replacements that were judged not to be loose on the radiographs were identified and analyzed. Fourteen of these cases were from a retrospective review of 474 cementless total hip replacements with a minimum two-year follow-up done by the authors. The incidence of the osteolysis was approximately 3% for femoral components made of both titanium-based alloys and cobalt-chrome-based alloys.

Four of the patients underwent reoperations for osteolysis. All four femoral components were found to be rigidly fixed to the skeleton at surgery. Three of these showed extensive bony ingrowth into the porous coatings on histology. The tissue in the region of osteolysis had a fibrous stroma. However, it contained focal aggregates of macrophages and rare giant cells. On light microscopy, evidence of fine intracellular particulate polyethylene and metallic debris was found in three of the cases. In the fourth, there was a fine fibrous membrane lining a cystic cavity. Although the tissue in the fourth case contained occasional macrophages, foreign material could not be identified on light microscopy. On electron microscopy, however, fine electron-dense particles consistent with metal were noted within the macrophages of this case.

Although these findings represent a small number of cases, they caution against the assumption that femoral osteolysis can be eliminated by using uncemented components. The precise cause for the osteolysis around uncemented porous-coated femoral components is not known. However, it seems that particulate debris from implanted biomaterials, such as metal and or polyethylene, seems to play an important role in the production of osteolysis around prosthetic components. The debris is much smaller and less frequent than that previously observed with cemented components.
Failure Mechanism of a Metal-Backed Patella: An Implant Retrieval Study
Authors: Stulberg BN , Schickendantz M , Merritt K , Bauer TW
Published: March 2009

Four patients with a single-design metal-backed patellar component underwent revision of patellar components of both knees. In each case, a markedly symptomatic side and a mildly symptomatic side were present. Implant retrieval analysis allowed the authors to confirm a mechanism of implant failure we have postulated previously. This type of failure was characterized as a Type II metal-backed patellar failure mechanism, as it is specifically related to failure of the ultrahigh-molecular-weight polyethylene (UHMWPE) and not to fixation of the implant. This failure pattern can result in massive intraarticular wear debris deposition.

The defined mechanism of failure is (1) UHMWPE deformation or wear, leading to (2) UHMWPE split or fracture at the implant periphery, (3) widening/deformation of the capture mechanism with loss of UHMWPE capture, and subsequent (4) metal-to-metal abrasion—the final component of debris generation.

The design parameters resulting in this failure mechanism include (1) UHMWPE that is too thin, (2) a capture mechanism dependent upon UHMWPE integrity, (3) a patellofemoral geometry that allows the possibility of edge loading.

As patellar fixation does not appear to be a clinically significant problem with cemented all-UHMWPE components, the use of metal-backed patellar components, by any technique or with any design, appears unwarranted.
Use of Profile Imaging to Assess Patellofemoral Congruity: Implications for Assessing Patellofemoral Wear in Total Knee Arthroplasty
Authors: Stulberg BN , de Swart RJ , Reger SI , Easley K
Published: March 2009

Profile imaging can be used to image the articulation of the patellofemoral joint of total knee implants. Using undamaged implants, conformity of the two articulating surfaces could be traced at angles of 50, 70, 90, and 120° of knee flexion. This was applied to five different styles of implants.

Femoral and patellar implants were retrieved from 40 patients undergoing revision total knee arthroplasty (TKA). Only all-polyethylene dome-shaped components were selected. Patellar implants were studied and graded for evidence of wear. Conformity data were then compared with wear data to assess the possible relationships between design parameters and subsequent wear.

Statistically significant differences in wear could be identified as they related to conformity of the articulating surfaces. Sharp patellofemoral edges and carbon-reinforced polyethylene (CRPE) patellar components were a particularly worrisome combination.

Profile imaging is a useful additional tool for assessing design features of implants and their subsequent relationships to implant-generated wear debris.
A Comparison of the Biocompatibility of Polymethyl Methacrylate Debris With and Without Titanium Debris: A Comparison of Two In Vivo Models
Authors: Cuckler JM , Mitchell J , Baker DG , Ducheyne P , Imonitie V , Schumacher HR
Published: March 2009

Evaluation of the biocompatibility of particulate debris is of paramount importance in improving the long-term results of joint replacement arthroplasty. This paper compares the results of intramuscular implants of particulates with the results of injection of particulates in the rat subcutaneous pouch model. The advantages of the subcutaneous pouch model lie in its ability to quantitate the cytokine response to particulates and in the similarity of the pseudosynovial membrane formed to the tissue observed to surround loose implants.
Preparation, Characterization, and Animal Testing for Biocompatibility of Metal Particles of Iron-, Cobalt-, and Titanium-Based Implant Alloys
Authors: Buchhorn GH , Willert H-G , Semlitsch M , Schoen R , Steinemann S , Schmidt M
Published: March 2009

Biocompatibility testing of metallic materials should include implantation of particulate material of high purity and small size. Powder production of iron-, cobalt-, and titanium-based implant metal alloys was achieved by a method of gentle rubbing of metal bars in closed containers of the same material. Suspensions were prepared for injection via a thin needle. Tissue reactions to the metal particle suspensions were evaluated up to one year after injection into various host tissues of rats. Tests for improvement of the vehicle were performed. A recommendation is given for metal powder production and for two compatible and resorbable vehicles for suspension of powders.
Climate Driven Durability Tester
Authors: Tanzer JD , Frankel LS
Published: March 2009

The “Climate Driven Durability Tester” (CDDT) tests channel movement capability of caulks and sealants under exposure conditions. A wide range of % movements, channel geometries, and substrates can be studied in the CDDT. Results are reported for a series of caulks exposed in aluminum and glass channels following 3, 7, and 16 months exposure. Adhesive failures noted in the present study do not completely correlate with ASTM C794 peel adhesion test results. The inability of ASTM C794 to distinguish between viscoelastic effects and adhesive bond strength may account for its unreliable prediction of adhesive performance in the CDDT.
A New Elastomeric Coating Technology for the 90's
Authors: Lefler HV
Published: March 2009

In the 20th century masonry buildings evolved from massive support systems to thin facades attached to structural supports. Minor cracks in this thin facade allowed severe water ingression and damage, and brought about the development of elastomeric coating system for above grade waterproofing. Emulsion progression from butadiene-styrene and vinyl acetate polymer, through acrylics, and now into the silicone emulsion systems, has resulted in increasingly superior waterproofing elastomers. This paperreviews the basic chemistry relevant to silicone emulsion elastomers, their relationship to current acrylic elastomeric coatings for weathering, and physical property profiles. Also discussed are silicone emulsion elastomeric coatings resistance to mildew, dirt, graffiti and staining.
Advances in One Part Polysulfide Sealant Technology
Authors: Fiorillo AR
Published: March 2009

One of the major drawbacks of one part polysulfide sealants is their extremely slow cure rates compared to other types of sealants.

Major studies have been conducted in an effort to find ways of accelerating the cure of one part polysulfide sealants. New formulating techniques and new developments in curative technology have shown that one part polysulfide sealants can be formulated that have cure rates similar to other generic types of sealants while maintaining good shelf life stability.

Sealants will be discussed that have been formulated based on these studies. These sealants have been tested and found to meet all the requirements of ASTM C-920.
Recent Developments in Quantitative Fractography
Authors: Gokhale AM , Drury WJ , Mishra S
Published: March 2009

Quantitative characterization of fracture surface topography is an important aspect of quantitative fractography. This contribution is concerned with the profilometric methods for the estimation of the important descriptors of the fracture surface topography. The parameters such as fracture surface roughness, tortuosity, fraction overlap, etc. are defined, and the profilometric measurements that enable the estimation of such parameters are described. Recent experimental data on the surface roughness and fractal dimension pertaining to creep and impact fracture surfaces are presented to demonstrate the utility of the topographic parameters.