Creep fracture

Penny, R. K.; Marriott, D. L.

doi:10.1007/978-94-011-0561-3_7

Cited by 4 publications

(6 citation statements)

References 15 publications

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“…Expressions for the functions f , g and h have been proposed by a large number of researchers. The most common forms for the stress, time and temperature functions are given in [3]. Note that for ceramics and fibres, power laws for f ( σ ) and g ( t ) and exponential law for h ( T ) are commonly used.…”

Section: Generalitiesmentioning

confidence: 99%

“…The design of CMC components for high-temperature applications must consider creep so that excessive strain or premature failure is avoided during the anticipated lifetime of the structure [3]. In contrast to ceramics, there are relatively few published reports about the creep of CMCs, although they are being developed for use in high-temperature structural applications.…”

Section: Introductionmentioning

confidence: 99%

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Review: creep of fibre-reinforced ceramic matrix composites

Lamon

2019

International Materials Reviews

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The content of the review covers, first, generalities on creep. Then, the creep of ceramics and fibres, that are key constituents of fibre-reinforced ceramic matrix composites (CMCs) are addressed. The general features of ceramic matrix composites that may influence the creep behaviour and creep rupture are discussed. Emphasis is placed on microstructure-property relationships and load sharing between fibres and matrix that are critical for CMCs. Then, creep tests and the creep behaviour of various types of fibre-reinforced composites are presented. Mechanisms and models are discussed. The influence of various factors including composite structure, constituent properties (matrix and fibres), interfacial properties and environmental conditions are examined. The paper focuses on non-oxide composites like SiC/SiC that received much attention during the last three decades. Creep of oxide ceramics, fibres and composites are addressed more briefly.

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Section: Generalitiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Review: creep of fibre-reinforced ceramic matrix composites

Lamon

2019

International Materials Reviews

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Section: Background and Literature Reviewmentioning

confidence: 99%

“…Such shortcomings led to the development of creep continuum damage mechanics (CDM) models [26,27]. These relate the creep strain rate to measurable, external parameters – stress, strain, temperature, and time – and to a number of internal state variables, , which provide a measure for accumulated damage [26]. A constitutive model is then proposed by an equation for the evolution of creep strain rate and by i equations for the evolution of : The origins of creep CDM lie in the attempts of Kachanov [28] and Rabotnov [29] to quantify damage evolution during tertiary creep using a single internal damage parameter.…”

Section: Background and Literature Reviewmentioning

confidence: 99%

Critical assessment 31: On the modelling of tertiary creep in single-crystal superalloys

Sulzer

Reed

2018

Materials Science and Technology

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Modelling of tertiary creep in single-crystal superalloys -operative over the majority of the temperature/stress regime of relevance -is assessed. Traditional, empirical approaches are useful for the prediction of component life; a modern trend is for more physically faithful models which account for microstructure and alloy composition. Calculations are made using different methods, to identify advantages/disadvantages, in an effort to approach best practice. The predictions are tested against experimental data. The creep resistance can be estimated to within approximately one-half of a Larson-Miller parameter, from an input of alloy composition, deformation conditions, and estimates of microstructural parameters, rate laws (and parameters therein), and physical constants. Different merit indices are considered to identify the most appropriate for compositional optimisation.

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“…A major concern in the evaluation of test data of small specimen creep testing techniques is their correlation with uniaxial creep data. The approach currently used for data conversion is the reference stress method [17,18]. For materials obeying the Norton creep law, here reported in Equation (2), where A′ and n are material constants, the reference stress method involves calculating two reference parameters, η and β , such that a relationship between the equivalent uniaxial stress, σ ref , and the applied stress, σ , and a relationship between the creep strain rate in the steady-state, , and the creep displacement rate obtained by SSTT, , are established. can be expressed as a function of the creep material properties, the dimensions of the specimen and the nominal stress, σ nom , as reported in Equation (3). The reference parameter η is defined as a material independent, non-dimensional constant such that the ratio is also constant with n .…”

Section: Specialised Small Specimen Creep Testingmentioning

confidence: 99%

The role of small specimen creep testing within a life assessment framework for high temperature power plant

Morris

Cacciapuoti

Sun

2017

International Materials Reviews

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The safe operation of components operating at high temperature and pressure faces numerous challenges associated with ageing materials and maintaining commercial viability whilst economies transition to a lower carbon future as part of their climate change commitments. Due to these challenges the plant operator faces increasing pressure to ensure that any capital or operational expenditures are optimised and must ensure that they duly recognise plant age, condition, operating regime and ultimately the planned closure date.This review, for the first time, describes how small specimen creep testing can be applied within a practical and deployable life assessment framework and in conjunction with other assessment techniques. The current state of the art for small specimen creep testing is critically reviewed; this also includes a review of traditional techniques used on site for the metallurgical assessment of material condition, with examples from site investigations and assessment campaigns in both conventional and nuclear plant applications.In order to enhance the current practice for assessing the condition of creep ageing components this review proposes the more proactive use of small specimen testing methods for the in-service condition assessment of power plant materials, notably earlier in the plant lifecycle and within a holistic life assessment framework. This is intended to provide a means of calibrating the time dependent response of the component or system being monitored, thereby providing a key reference in-service strain rate measurement, or material property evaluation, that can subsequently be used with other traditionally deployed assessment methods to define a more targeted and cost-effective forward inspection plan. The review describes how small specimen creep testing methods and other complementary tools can be use in a new and structured approach to life management.The current status of small specimen testing methods, for both conventional and nuclear applications, is described along with a detailed discussion on current practice for in-service creep life assessment, with a case study used to illustrate the main principals. A case study is presented for ageing CMV (0.5%Cr0.5%Mo0.25%V) main steam pipework due to the extensive amount of through life data available, which highlights the particular challenges associated with the interpretation of various types of site outage inspection data, in conjunction with on-load plant operational data. The current approach to the assessment of component condition follows well established inspection based practices defined in various industry good practice guides, with expert elicitation and experience used to judge the condition of the component, system and operational risk on return to service.This review proposes a new approach to the holistic life assessment of high temperature plant, with a particular emphasis on more proactive use of small specimen testing. In addition, the review has 2 highlighted other aspects of the current approach to in-...

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Creep fracture

Cited by 4 publications

References 15 publications

Review: creep of fibre-reinforced ceramic matrix composites

Review: creep of fibre-reinforced ceramic matrix composites

Critical assessment 31: On the modelling of tertiary creep in single-crystal superalloys

The role of small specimen creep testing within a life assessment framework for high temperature power plant

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