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life fraction rule
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in Elevated-Temperature Life Assessment for Turbine Components, Piping, and Tubing
> Failure Analysis and Prevention
Published: 01 January 2002
Fig. 15 Residual life predictions using the life fraction rule from increased stress and temperature tests for 1Cr-0.5Mo steel
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Book: Fatigue and Fracture
Series: ASM Handbook
Volume: 19
Publisher: ASM International
Published: 01 January 1996
DOI: 10.31399/asm.hb.v19.a0002390
EISBN: 978-1-62708-193-1
... Abstract The approaches to spectrum life prediction in components can be classified into two types, namely, history-based methods, using the life-fraction rule or other damage rules, and postservice evaluation methods. This article discusses the variables affecting the material crack growth...
Abstract
The approaches to spectrum life prediction in components can be classified into two types, namely, history-based methods, using the life-fraction rule or other damage rules, and postservice evaluation methods. This article discusses the variables affecting the material crack growth rate behavior and those essential elements in making spectrum crack growth life prediction. It provides information on life assessment for bulk creep damage.
Series: ASM Handbook Archive
Volume: 11
Publisher: ASM International
Published: 01 January 2002
DOI: 10.31399/asm.hb.v11.a0003517
EISBN: 978-1-62708-180-1
.... The article discusses metallurgical instabilities of steel-based alloys and nickel-base superalloys. It provides information on several life assessment methods, namely, the life fraction rule, parameter-based assessments, the thermal-mechanical fatigue, coating evaluations, hardness testing, microstructural...
Abstract
This article focuses on the life assessment methods for elevated-temperature failure mechanisms and metallurgical instabilities that reduce life or cause loss of function or operating time of high-temperature components, namely, gas turbine blade, and power plant piping and tubing. The article discusses metallurgical instabilities of steel-based alloys and nickel-base superalloys. It provides information on several life assessment methods, namely, the life fraction rule, parameter-based assessments, the thermal-mechanical fatigue, coating evaluations, hardness testing, microstructural evaluations, the creep cavitation damage assessment, the oxide-scale-based life prediction, and high-temperature crack growth methods.
Image
in Elevated-Temperature Life Assessment for Turbine Components, Piping, and Tubing
> Failure Analysis and Prevention
Published: 01 January 2002
(ductile) is a ductile tubing steel. (a) Correlation between expected life based on life fraction rule and the actually observed life in postexposure accelerated tests. (b) The expended life fraction under service conditions versus the remaining life fraction as determined from postexposure accelerated
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Image
in Elevated-Temperature Life Assessment for Turbine Components, Piping, and Tubing
> Failure Analysis and Prevention
Published: 01 January 2002
Fig. 33 Stress-rupture curves for virgin material and predamaged material showing the various life fractions. Virgin material rupture life at 575 °C (1065 °F) is 62,210 h Estimated remaining life at 575 °C (1065 °F) for predamaged samples based on: Symbol Damage fraction Life
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Image
in Elevated-Temperature Life Assessment for Turbine Components, Piping, and Tubing
> Failure Analysis and Prevention
Published: 01 January 2002
Fig. 32 Photograph of catastrophic fishmouth rupture of seam-welded high-energy piping. These failures are typically brittle and are not predicted using simple life fraction rule calculations.
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Series: ASM Handbook
Volume: 6
Publisher: ASM International
Published: 01 January 1993
DOI: 10.31399/asm.hb.v06.a0001477
EISBN: 978-1-62708-173-3
... assumed material properties and damage rules. The most widely applied creep-life fraction rule can be expressed as: (Eq 7) Σ t i t r = 1 where t i is the time spent at a given stress and temperature and t r is the rupture life for the same test conditions. When the damage...
Abstract
Fitness-for-service assessment procedures can be used to assess the integrity, or remaining life, of components in service. Depending on the operating environment and the nature of the applied loading, a structure can fail by a number of different modes: brittle fracture, ductile fracture, plastic collapse, fatigue, creep, corrosion, and buckling. This article focuses on the broad categories of these failure modes: fracture, fatigue, environmental cracking, and high-temperature creep. It also discusses the benefits of a fitness-for-service approach.
Series: ASM Handbook
Volume: 20
Publisher: ASM International
Published: 01 January 1997
DOI: 10.31399/asm.hb.v20.a0002472
EISBN: 978-1-62708-194-8
... of temperature and stress on the extent of cracking at failure. Most theories assume that failure occurs at some critical cavity distribution or crack size. However, it has been shown that the extent of cavitation at failure or at any given fraction of the failure life is very sensitive to the test conditions...
Abstract
This article reviews the basic mechanisms of elevated-temperature behavior and associated design considerations, with an emphasis on metals. It discusses the key concepts of elevated-temperature design. These include plastic instability at elevated temperatures; deformation mechanisms and strain components associated with creep processes; stress and temperature dependence; fracture at elevated temperatures; and environmental effects. The article describes the basic presentation and analysis methods for creep rupture. It provides information on the application of these methods to materials selection and the setting of basic design rules. The article examines the limitations of high-temperature components as well as the alternative design approaches and tests for most high-temperature components.
Book: Fatigue and Fracture
Series: ASM Handbook
Volume: 19
Publisher: ASM International
Published: 01 January 1996
DOI: 10.31399/asm.hb.v19.a0002387
EISBN: 978-1-62708-193-1
... Abstract This article focuses on the subject of proactive or predictive maintenance with particular emphasis on the control and prediction of corrosion damage for life extension and failure prevention. It discusses creep life assessment from the perspective of creep-rupture properties...
Abstract
This article focuses on the subject of proactive or predictive maintenance with particular emphasis on the control and prediction of corrosion damage for life extension and failure prevention. It discusses creep life assessment from the perspective of creep-rupture properties and creepcrack growth. Practical methods based on replication and parametric approaches are also discussed.
Series: ASM Handbook
Volume: 8
Publisher: ASM International
Published: 01 January 2000
DOI: 10.31399/asm.hb.v08.a0003289
EISBN: 978-1-62708-176-4
..., performance often roughly follows the “life-fraction rule” or “linear cumulative damage rule” ( Ref 54 ), in which the percentage of total life consumed for each period of fixed temperature and stress is represented as: % total life = actual time at the given conditions...
Abstract
This article discusses the methods for assessing creep-rupture properties, particularly, nonclassical creep behavior. The determination of creep-rupture behavior under the conditions of intended service requires extrapolation and/or interpolation of raw data. The article describes the various techniques employed for data handling of most materials and applications of engineering interest. These techniques include graphical methods, methods using time-temperature parameters, and methods used for estimations when data are sparse or hard to obtain. The article reviews the estimation of required creep-rupture properties based on insufficient data. Methods for evaluation of remaining creep-rupture life, including parametric modeling, isostress testing, accelerated creep testing, evaluation by the Monkman-Grant coordinates, and the Materials Properties Council (MPC) Omega method, are also reviewed.
Series: ASM Handbook
Volume: 11A
Publisher: ASM International
Published: 30 August 2021
DOI: 10.31399/asm.hb.v11A.a0006807
EISBN: 978-1-62708-329-4
... Abstract This article provides some new developments in elevated-temperature and life assessments. It is aimed at providing an overview of the damage mechanisms of concern, with a focus on creep, and the methodologies for design and in-service assessment of components operating at elevated...
Abstract
This article provides some new developments in elevated-temperature and life assessments. It is aimed at providing an overview of the damage mechanisms of concern, with a focus on creep, and the methodologies for design and in-service assessment of components operating at elevated temperatures. The article describes the stages of the creep curve, discusses processes involved in the extrapolation of creep data, and summarizes notable creep constitutive models and continuum damage mechanics models. It demonstrates the effects of stress relaxation and redistribution on the remaining life and discusses the Monkman-Grant relationship and multiaxiality. The article further provides information on high-temperature metallurgical changes and high-temperature hydrogen attack and the steps involved in the remaining-life prediction of high-temperature components. It presents case studies on heater tube creep testing and remaining-life assessment, and pressure vessel time-dependent stress analysis showing the effect of stress relaxation at hot spots.
Book: Fatigue and Fracture
Series: ASM Handbook
Volume: 19
Publisher: ASM International
Published: 01 January 1996
DOI: 10.31399/asm.hb.v19.a0002365
EISBN: 978-1-62708-193-1
... on their manner of use and limitations. The use of the Palmgren-Miner rule for life prediction for variable amplitude loading is also discussed. fatigue life Palmgren-Miner rule strain-based approach stress-based approach variable amplitude load FATIGUE LIFE ESTIMATES are often needed...
Abstract
This article discusses two major approaches in estimating fatigue life from the viewpoint of their use as engineering methods. These include the stress-based (S-N curve) approach and strain-based approach. The stress-based and strain-based approaches are compared, with some comments on their manner of use and limitations. The use of the Palmgren-Miner rule for life prediction for variable amplitude loading is also discussed.
Series: ASM Handbook
Volume: 20
Publisher: ASM International
Published: 01 January 1997
DOI: 10.31399/asm.hb.v20.a0002456
EISBN: 978-1-62708-194-8
... is then expressed in “design life fraction” using a company-specified design life, for example, 20 years. The 12 candidate materials are then ranked in order of decreasing life expectancy. A query for tube materials for a hypothetical location (with extremely polluted, sulfide-containing harbor water) resulted...
Abstract
This article provides a description of various systems for computer-aided materials selection that deals primarily with promising prototypes that have emerged for various applications. These include expert systems, quantitative selection systems, qualitative and experiential selection systems, and object-oriented systems.
Series: ASM Handbook
Volume: 20
Publisher: ASM International
Published: 01 January 1997
DOI: 10.31399/asm.hb.v20.a0002451
EISBN: 978-1-62708-194-8
... Abstract This article provides an overview of cost analysis in materials selection. It discusses the several categories of alternatives for cost analysis. These include rules of thumb, accounting methods, and analytical methods. The article describes the methods for evaluating materials...
Abstract
This article provides an overview of cost analysis in materials selection. It discusses the several categories of alternatives for cost analysis. These include rules of thumb, accounting methods, and analytical methods. The article describes the methods for evaluating materials alternatives on the basis of both direct economic costs and indirect social costs. It considers the life cycle costs of alternative body-in-white designs and life cycle analysis. The various elements of cost are introduced with a case study concerned with the manufacture, use, and disposal of the automobile body-in-white.
Series: ASM Handbook Archive
Volume: 11
Publisher: ASM International
Published: 01 January 2002
DOI: 10.31399/asm.hb.v11.a0003512
EISBN: 978-1-62708-180-1
... has elapsed. Calculations predict life exhaustion. Service time has reached some arbitrarily chosen fraction of calculated or experimental failure life. Previous failure statistics indicate high probability of failure. Frequency of repair renders continued operation uneconomical...
Abstract
This article provides an overview of the structural design process and discusses the life-limiting factors, including material defects, fabrication practices, and stress. It details the role of a failure investigator in performing nondestructive inspection. The article provides information on fatigue life assessment, elevated-temperature life assessment, and fitness-for-service life assessment.
Series: ASM Handbook
Volume: 17
Publisher: ASM International
Published: 01 August 2018
DOI: 10.31399/asm.hb.v17.a0006462
EISBN: 978-1-62708-190-0
...-life and damage tolerant design approach is evident by contrasting Division 1 and Division 2 rules within Section VIII. But first a simple NDT method specific to pressure vessels is considered. Pressure vessels have an inherent NDT and SHM mechanism: if a crack pathway exists between the pressurized...
Abstract
Both nondestructive testing (NDT) and nondestructive evaluation (NDE) use noninvasive measurement techniques to gain information about defects and various properties of materials, components, and structures. This article begins with a discussion on the historical development of quantitative measurement techniques, evaluation reliability, and quantitative interpretation of nondestructive inspection methods. The common nondestructive evaluation methods, along with their uses and limitations, are summarized in a table. The article conceptually illustrates the interplay of NDE and fracture mechanics in the damage tolerant approach. It concludes with information on pressure vessel applications that can be separated into three protocols used by military nuclear power, commercial nuclear power, and non-nuclear pressure vessels and/or fired boilers.
Book: Composites
Series: ASM Handbook
Volume: 21
Publisher: ASM International
Published: 01 January 2001
DOI: 10.31399/asm.hb.v21.a0003382
EISBN: 978-1-62708-195-5
... incorporated into existing design practices. These models are simply applied to multistress-level loading and are traditionally associated with safelife. Palmgren-Miner Rule Perhaps the most simple life prediction model is the Palmgren- Miner rule ( Ref 27 , 28 ): (Eq 6) ∑ i = 1 m n...
Abstract
In the design of composite structures for durability and damage tolerance, the primary concerns are out-of-plane failures, such as delamination, material degradation associated with environment, stability under compression loading, large degree of scatter in fatigue life, and bearing failure of joints. This article presents an introductory discussion on the fatigue damage process, methodologies assessing fatigue behavior, and life prediction models. It describes the damage mechanisms introduced for a quasi-isotropic laminate under tension-compression fatigue loading. Delamination is a critical issue in fatigue and generally results from high interlaminar normal and shear stresses. The article schematically illustrates the structural elements in which high interlaminar stresses are common. It concludes with a discussion on the classification of fatigue models such as mechanistic or phenomenological, for composite materials under cyclic loading.
Series: ASM Handbook
Volume: 20
Publisher: ASM International
Published: 01 January 1997
DOI: 10.31399/asm.hb.v20.a0002487
EISBN: 978-1-62708-194-8
.... As with production machining systems, the general design-for-machining rules discussed in the next section of this article are broadly applicable to these systems. In CNC systems, however, the actual machining time consumes a smaller fraction of the total processing time. Reducing the time required for noncutting...
Abstract
Machining or material removal processes are secondary manufacturing operations that are used to achieve precise tolerances or to impart controlled surface finishes to a part. This article summarizes rules for designing parts to improve machined part quality and reduce machining costs in mass and batch production environments. It discusses the factors affecting the total cost of a machining operation, including raw material costs, labor costs, and equipment costs. The article describes three types of machining systems, namely, general-purpose machine tools, production machining systems, and computer numerically controlled (CNC) machining systems. It reviews general design-for-machining rules that are applicable to all parts, regardless of the type of equipment used to produce them. Special considerations for production machining systems and CNC machining systems are discussed. The article describes the structure and typical uses of computer-aided process planning and design-for-manufacturing programs.
Series: ASM Handbook
Volume: 11A
Publisher: ASM International
Published: 30 August 2021
DOI: 10.31399/asm.hb.v11A.a0006802
EISBN: 978-1-62708-329-4
... elapsed. Calculations predict life exhaustion. Service time has reached some arbitrarily chosen fraction of calculated or experimental failure life. Previous failure statistics indicate high probability of failure. Frequency of repair renders continued operation uneconomical. Nondestructive...
Abstract
Life assessment of structural components is used to avoid catastrophic failures and to maintain safe and reliable functioning of equipment. The failure investigator's input is essential for the meaningful life assessment of structural components. This article provides an overview of the structural design process, the failure analysis process, the failure investigator's role, and how failure analysis of structural components integrates into the determination of remaining life, fitness-for-service, and other life assessment concerns. The topics discussed include industry perspectives on failure and life assessment of components, structural design philosophies, the role of the failure analyst in life assessment, and the role of nondestructive inspection. They also cover fatigue life assessment, elevated-temperature life assessment, fitness-for-service life assessment, brittle fracture assessments, corrosion assessments, and blast, fire, and heat damage assessments.
Series: ASM Handbook
Volume: 11A
Publisher: ASM International
Published: 30 August 2021
DOI: 10.31399/asm.hb.v11A.a0006819
EISBN: 978-1-62708-329-4
..., Division 2, Alternate Rules for Pressure Vessels , followed in 1968 ( Ref 13 ). Section VIII, Division 1 of the ASME B&PV Code ( Ref 14 ), arguably one of the most widely used pressure vessel design codes for unfired and nonnuclear equipment, does not include explicit fatigue design life evaluation...
Abstract
This article offers an overview of fatigue fundamentals, common fatigue terminology, and examples of damage morphology. It presents a summary of relevant engineering mechanics, cyclic plasticity principles, and perspective on the modern design by analysis (DBA) techniques. The article reviews fatigue assessment methods incorporated in international design and post construction codes and standards, with special emphasis on evaluating welds. Specifically, the stress-life approach, the strain-life approach, and the fracture mechanics (crack growth) approach are described. An overview of high-cycle welded fatigue methods, cycle-counting techniques, and a discussion on ratcheting are also offered. A historical synopsis of fatigue technology advancements and commentary on component design and fabrication strategies to mitigate fatigue damage and improve damage tolerance are provided. Finally, the article presents practical fatigue assessment case studies of in-service equipment (pressure vessels) that employ DBA methods.
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