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Application of Frequency-Modified Life Approach to the Low-Cycle Fatigue Behavior of Type 304 Stainless Steel

Description: The application of the frequency-modified life equation to fatigue life prediction has been critically examined using the extensive fatigue data generated for Type 304 stainless steel at 1100 degrees F under a variety of cyclic-loading conditions. The parameters that enter into the frequency-modified life equation vary with strain rate and show a transition coinciding with the frequency of cycling at which a change in the fracture appearance from predominantly transgranular to predominantly intergranular failure mode or vice versa occurs. The accuracy in life prediction is improved when the effect of strain rate on life-predictive parameters is considered. It is shown how the effect of compressive and symmetric hold time on fatigue life can be taken into account. A comparison between the frequency-modified life approach of Coffin and the damage-rate approach recently developed by Majumdar and Maiya is also made to show the importance of wave-shape on low-cycle fatigue life.
Date: May 1976
Creator: Maiya, P. S. & Majumdar, S.
Partner: UNT Libraries Government Documents Department

Stress Voiding in IC Interconnects - Rules of Evidence for Failure Analysts

Description: Mention the words ''stress voiding'', and everyone from technology engineer to manager to customer is likely to cringe. This IC failure mechanism elicits fear because it is insidious, capricious, and difficult to identify and arrest. There are reasons to believe that a damascene-copper future might be void-free. Nevertheless, engineers who continue to produce ICs with Al-alloy interconnects, or who assess the reliability of legacy ICs with long service life, need up-to-date insights and techniques to deal with stress voiding problems. Stress voiding need not be fearful. Not always predictable, neither is it inevitable. On the contrary, stress voids are caused by specific, avoidable processing errors. Analytical work, though often painful, can identify these errors when stress voiding occurs, and vigilance in monitoring the improved process can keep it from recurring. In this article, they show that a methodical, forensics approach to failure analysis can solve suspected cases of stress voiding. This approach uses new techniques, and patiently applies familiar ones, to develop evidence meeting strict standards of proof.
Date: September 17, 1999
Creator: FILTER, WILLIAM F.
Partner: UNT Libraries Government Documents Department

Report of the Workshop on Petascale Systems Integration for LargeScale Facilities

Description: There are significant issues regarding Large Scale System integration that are not being addressed in other forums such as current research portfolios or vendor user groups. Unfortunately, the issues in the area of large-scale system integration often fall into a netherworld; not research, not facilities, not procurement, not operations, not user services. Taken together, these issues along with the impact of sub-optimal integration technology means the time required to deploy, integrate and stabilize large scale system may consume up to 20 percent of the useful life of such systems. Improving the state of the art for large scale systems integration has potential to increase the scientific productivity of these systems. Sites have significant expertise, but there are no easy ways to leverage this expertise among them . Many issues inhibit the sharing of information, including available time and effort, as well as issues with sharing proprietary information. Vendors also benefit in the long run from the solutions to issues detected during site testing and integration. There is a great deal of enthusiasm for making large scale system integration a full-fledged partner along with the other major thrusts supported by funding agencies in the definition, design, and use of a petascale systems. Integration technology and issues should have a full 'seat at the table' as petascale and exascale initiatives and programs are planned. The workshop attendees identified a wide range of issues and suggested paths forward. Pursuing these with funding opportunities and innovation offers the opportunity to dramatically improve the state of large scale system integration.
Date: October 1, 2007
Creator: Kramer, William T.C.; Walter, Howard; New, Gary; Engle, Tom; Pennington, Rob; Comes, Brad et al.
Partner: UNT Libraries Government Documents Department

Assessing the operational life of flexible printed boards intended for continuous flexing applications : a case study.

Description: Through the vehicle of a case study, this paper describes in detail how the guidance found in the suite of IPC (Association Connecting Electronics Industries) publications can be applied to develop a high level of design assurance that flexible printed boards intended for continuous flexing applications will satisfy specified lifetime requirements.
Date: January 1, 2011
Creator: Beck, David Franklin
Partner: UNT Libraries Government Documents Department

Issues Impacting Refractory Service Life in Biomass/Waste Gasification

Description: Different carbon sources are used, or are being considered, as feedstock for gasifiers; including natural gas, coal, petroleum coke, and biomass. Biomass has been used with limited success because of issues such as ash impurity interactions with the refractory liner, which will be discussed in this paper.
Date: March 1, 2007
Creator: Bennett, J.P.; Kwong, K.-S. & Powell, C.A.
Partner: UNT Libraries Government Documents Department

Nondestructive Evaluation of Ceramic Candle Filters Using Vibration Response

Description: This study aims at the development of an effective nondestructive evaluation technique to predict the remaining useful life of a ceramic candle filter during a power plant's annual maintenance shutdown. The objective of the present on-going study is to establish the vibration signatures of ceramic candle filters at varying degradation levels due to different operating hours, and to study the various factors involving the establishment of the signatures.
Date: July 1, 1997
Creator: Chen, Roger H. L.; Kiriakidis, Alejandro C. & Peng, Steve W.
Partner: UNT Libraries Government Documents Department

Microelectronics plastic molded packaging

Description: The use of commercial off-the-shelf (COTS) microelectronics for nuclear weapon applications will soon be reality rather than hearsay. The use of COTS for new technologies for uniquely military applications is being driven by the so-called Perry Initiative that requires the U.S. Department of Defense (DoD) to accept and utilize commercial standards for procurement of military systems. Based on this philosophy, coupled with several practical considerations, new weapons systems as well as future upgrades will contain plastic encapsulated microelectronics. However, a conservative Department of Energy (DOE) approach requires lifetime predictive models. Thus, the focus of the current project is on accelerated testing to advance current aging models as well as on the development of the methodology to be used during WR qualification of plastic encapsulated microelectronics. An additional focal point involves achieving awareness of commercial capabilities, materials, and processes. One of the major outcomes of the project has been the definition of proper techniques for handling and evaluation of modern surface mount parts which might be used in future systems. This program is also raising the familiarity level of plastic within the weapons complex, allowing subsystem design rules accommodating COTS to evolve. A two year program plan is presented along with test results and commercial interactions during this first year.
Date: February 1, 1997
Creator: Johnson, D.R.; Palmer, D.W. & Peterson, D.W.
Partner: UNT Libraries Government Documents Department

Reliability performance of pulse discharge capacitors

Description: There is a void of public specifications for pulse discharge capacitor applications. Sandia National Laboratories has developed, over the past 25 years, specifications and test procedures for evaluating capacitor designs for this specialized use. There are three primary destructive tests that are used to assess the reliability potential of a given design at a required rated voltage. These are ultimate short time breakdown strength, life at voltage, and pulse discharge life. The strategy of the method is to accelerate the test conditions so that failures are observable and then extrapolate to the desired use conditions where the failure rates are low. This paper will present the statistical methodologies employed to analyze experimental data and to provide a point estimate of reliability with a lower confidence bound as a function of rated voltage. In addition, methods for establishing lot-acceptance-criteria specifications will be discussed. The techniques will be illustrated with actual data on a commercially available, low-inductance, pulse-discharge capacitor. The capacitor is an impregnated dual dielectric (mica-paper/polymer film), extended-foil type.
Date: February 1, 1997
Creator: Edwards, L.R.
Partner: UNT Libraries Government Documents Department

Advanced thermometrics for fossil power plant process improvement

Description: Improved temperature measurements in fossil power plants can reduce heat rate and uncertainties in power production efficiencies, extend the life of plant components, reduce maintenance costs, and lessen emissions. Conventional instruments for measurement of combustion temperatures, steam temperatures, and structural component temperatures can be improved by better specification, in situ calibration, signal processing, and performance monitoring. Innovative instruments can enhance, augment, or replace conventional instruments. Several critical temperatures can be accessed using new methods that were impossible with conventional instruments. Such instruments include high temperature resistance temperature detectors (RTDs), thermometric phosphors, inductive thermometry, and ultrasonic thermometry.
Date: April 30, 1996
Creator: Shepard, R.L.; Weiss, J.M. & Holcomb, D.E.
Partner: UNT Libraries Government Documents Department

Ensuring critical event sequences in high consequence computer based systems as inspired by path expressions

Description: The goal of our work is to provide a high level of confidence that critical software driven event sequences are maintained in the face of hardware failures, malevolent attacks and harsh or unstable operating environments. This will be accomplished by providing dynamic fault management measures directly to the software developer and to their varied development environments. The methodology employed here is inspired by previous work in path expressions. This paper discusses the perceived problems, a brief overview of path expressions, the proposed methods, and a discussion of the differences between the proposed methods and traditional path expression usage and implementation.
Date: February 1, 1997
Creator: Kidd, M.E.C.
Partner: UNT Libraries Government Documents Department

HWVP melter lifetime prediction letter

Description: Preliminary predictions were made of the time to reach hypothesized operational limits of the HWVP melter due to build up of a noble metals sludge layer on the melter floor. Predictions were made with the TEMPEST computer program, Version T2.9h, for use in the MPA activity in the Pacific Northwest Laboratory`s (PNL) Hanford Waste Vitrification Plant (HWVP) Technology Development (PHTD) effort. The NWEST computer program (Trent and Eyler 1993) is a PNL-MA-70/Part 2 -- Good Practices Standard (QA Level III) research and development software tool.
Date: March 1, 1996
Creator: Eyler, L.L.; Mahoney, L.A. & Elliott, M.L.
Partner: UNT Libraries Government Documents Department

Structural acceptance criteria for the evaulation of existing double-shell waste storage tanks located at the Hanford site, Richland, Washington

Description: The structural acceptance criteria contained herein for the evaluation of existing underground double-shell waste storage tanks located at the Hanford Site is part of the Life Management/Aging Management Program of the Tank Waste Remediation System. The purpose of the overall life management program is to ensure that confinement of the waste is maintained over the required service life of the tanks. Characterization of the present condition of the tanks, understanding and characterization of potential degradation mechanisms, and development of tank structural acceptance criteria based on previous service and projected use are prerequisites to assessing tank integrity, to projecting the length of tank service, and to developing and applying prudent fixes or repairs. The criteria provided herein summarize the requirements for the analysis and structural qualification of the existing double-shell tanks for continued operation. Code reconciliation issues and material degradation under aging conditions are addressed. Although the criteria were developed for double-shell tanks, many of the provisions are equally applicable to single-shell tanks. However, the criteria do not apply to the evaluation of tank appurtenances and buried piping.
Date: September 1, 1995
Creator: Julyk, L.J.; Day, A.D.; Dyrness, A.D.; Moore, C.J.; Peterson, W.S.; Scott, M.A. et al.
Partner: UNT Libraries Government Documents Department

System reliability assessment with an approximate reasoning model

Description: The projected service life of weapons in the US nuclear stockpile will exceed the original design life of their critical components. Interim metrics are needed to describe weapon states for use in simulation models of the nuclear weapons complex. The authors present an approach to this problem based upon the theory of approximate reasoning (AR) that allows meaningful assessments to be made in an environment where reliability models are incomplete. AR models are designed to emulate the inference process used by subject matter experts. The emulation is based upon a formal logic structure that relates evidence about components. This evidence is translated using natural language expressions into linguistic variables that describe membership in fuzzy sets. The authors introduce a metric that measures the acceptability of a weapon to nuclear deterrence planners. Implication rule bases are used to draw a series of forward chaining inferences about the acceptability of components, subsystems and individual weapons. They describe each component in the AR model in some detail and illustrate its behavior with a small example. The integration of the acceptability metric into a prototype model to simulate the weapons complex is also described.
Date: December 1998
Creator: Eisenhawer, S. W.; Bott, T. F.; Helm, T. M. & Boerigter, S. T.
Partner: UNT Libraries Government Documents Department

Principles of As-Built Engineering

Description: As-Built Engineering is a product realization methodology founded on the notion that life-cycle engineering should be based on what is actually produced and not on what is nominally designed. As-Built Engineering is a way of thinking about the production realization process that enables customization in mass production environments. It questions the relevance of nominal based methods of engineering and the role that tolerancing plays in product realization. As-Built Engineering recognizes that there will always be errors associated with manufacturing that cannot be controlled and therefore need to be captured in order to fully characterize each individual product`s unique attributes. One benefit of As-Built Engineering is the ability to provide actual product information to designers and analysts enabling them to verify their assumptions using actual part and assembly data. Another benefit is the ability to optimize new and re-engineered assemblies.
Date: November 1, 1996
Creator: Dolin, R.M. & Hefele, J.
Partner: UNT Libraries Government Documents Department

Double-shell tank remaining useful life estimates

Description: The existing 28 double-shell tanks (DSTS) at Hanford are currently planned to continue operation through the year 2028 when disposal schedules show removal of waste. This schedule will place the DSTs in a service life window of 4O to 60 years depending on tank construction date and actual retirement date. This paper examines corrosion- related life-limiting conditions of DSTs and reports the results of remaining useful life models developed for estimating remaining tank life. Three models based on controllable parameters such as temperature, chemistry, and relative humidity are presented for estimates to the year in which a particular DST may receive a breach in the primary tank due to pitting in the liquid or vapor region. Pitting is believed to be the life-limiting condition for DSTs,however, the region of the most aggressive pitting (vapor space or liquid) requires further investigation. The results of the models presented suggest none of the existing DSTs should fail by through-wall pitting until well beyond scheduled retrieval in 2028. The estimates of tank breach years (the year in which a tank may be expected to breach the primary tank wall) range from 2056 for pitting corrosion in the liquid region of tank 104-AW to beyond the next millennium for several tanks in the vapor region.
Date: December 2, 1996
Creator: Anantatmula, R. P.
Partner: UNT Libraries Government Documents Department

Methods for Predicting More Confident Lifetimes of Seals in Air Environments

Description: We have been working for many years to develop improved methods for predicting the lifetimes of polymers exposed to air environments and have recently turned our attention to seal materials. This paper describes an extensive study on a butyl material using elevated temperature compression stress-relaxation (CSR) techniques in combination with conventional oven aging exposures. The results initially indicated important synergistic effects when mechanical strain is combined with oven aging, as well as complex, non-Arrhenius behavior of the CSR results. By combining modeling and experiments, we show that diffusion-limited oxidation (DLO) anomalies dominate traditional CSR experiments. A new CSR approach allows us to eliminate DLO effects and recover Arrhenius behavior. Furthermore, the resulting CSR activation energy (E{sub a}) from 125 C to 70 C is identical to the activation energies for the tensile elongation and for the oxygen consumption rate of unstrained material over similar temperature ranges. This strongly suggests that the same underlying oxidation reactions determine both the unstrained and strained degradation rates. We therefore utilize our ultrasensitive oxygen consumption rate approach down to 23 C to show that the CSR E{sub a} likely remains unchanged when extrapolated below 70 C, allowing very confident room temperature lifetime predictions for the butyl seal.
Date: March 5, 1999
Creator: Celina, M.; Gillen, K.T. & Keenan, M.R.
Partner: UNT Libraries Government Documents Department

Advanced cryogenics for cutting tools. Final report

Description: The purpose of the investigation was to determine if cryogenic treatment improved the life and cost effectiveness of perishable cutting tools over other treatments or coatings. Test results showed that in five of seven of the perishable cutting tools tested there was no improvement in tool life. The other two tools showed a small gain in tool life, but not as much as when switching manufacturers of the cutting tool. The following conclusions were drawn from this study: (1) titanium nitride coatings are more effective than cryogenic treatment in increasing the life of perishable cutting tools made from all cutting tool materials, (2) cryogenic treatment may increase tool life if the cutting tool is improperly heat treated during its origination, and (3) cryogenic treatment was only effective on those tools made from less sophisticated high speed tool steels. As a part of a recent detailed investigation, four cutting tool manufacturers and two cutting tool laboratories were queried and none could supply any data to substantiate cryogenic treatment of perishable cutting tools.
Date: October 1, 1996
Creator: Lazarus, L. J.
Partner: UNT Libraries Government Documents Department

HFIR Vessel Probabilistic Fracture Analysis, Considering Success of Hydrostatic Proof Tests

Description: Periodic hydrostatic proof testing and probabilistic fracture mechanics analyses are performed to demonstrate the structural integrity and useful life of the High Flux Isotope Reactor (HFIR) pressure vessel. Calculations of the hydro-test conditions (pressure, temperature, and frequency) and of the probability of failure account for vessel degradation (flaw growth and radiation-induced embrittlement) that takes place between tests and of the credible worst-case-operating condition. The specified useful life of the vessel is limited by specified maximum permissible calculated probabilities of failure for hydro-test and worst-case-operating conditions. The probability of failure can be calculated with or without accounting for the success (absence of failure) of a test, but if success is accounted for, the calculated probabilities are less and thus the maximum permissible life greater. This report describes a simple method for including the success of a test.
Date: January 1, 1999
Creator: Cheverton, R.D.
Partner: UNT Libraries Government Documents Department

ITP Materials Compatibility Issues

Description: Based on information provided by ITP, normal operation will consist of controlled exposure to benzene and TBP concentrations of 300 and 100 ppm, respectively, in an approximate 5M NaOH solution at temperatures as high as 50 degrees C. Other compounds present in the filtrate solution were much lower in concentration and were not tested. In addition, levels as high as 1000 ppm benzene or TBP may be reached. It is assumed that the TBP will be maintained at a constant concentration to control foaming behavior.
Date: September 1, 1998
Creator: Skidmore, T.E.
Partner: UNT Libraries Government Documents Department