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Life Assessment based on the Small Punch Test and the Wilshire Equations / THOMAS WILLIAMS

Swansea University Author: THOMAS WILLIAMS

  • Redacted version - open access under embargo until: 20th June 2028

DOI (Published version): 10.23889/SUthesis.63768

Abstract

Uniaxial creep data plays a key role in predicting the life cycle of different alloys and parts present in power generation and aero engines, such as RR1000 which is used in turbine disc components. Modern studies have found success in using the Wilshire equations as a creep lifing method, making it...

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Published: Swansea, Wales, UK 2023
Institution: Swansea University
Degree level: Doctoral
Degree name: Ph.D
Supervisor: Evans, Mark. and Williams, S. J.
URI: https://cronfa.swan.ac.uk/Record/cronfa63768
first_indexed 2023-07-03T15:56:18Z
last_indexed 2024-11-25T14:12:53Z
id cronfa63768
recordtype RisThesis
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Improvements in extrapolative ability can be achieved by uniaxial testing, at accelerated temperatures but operational stresses (or visa versa), utilising specimens cut from components that have not yet failed but have been in service for long periods of time. The shorter residual lives then require less extrapolation with respect to stress or temperature - but creating such test specimens leads to component destruction which is very costly. To further build on the idea behind abridged testing, the small punch test has been developed to produce data from service parts in power plants without compromising the ongoing structural strength of the component. This is achieved by obtaining thin slices of material from component and then applying a constant load - via a punch &#x2013; to a machined disc. However, there has been little application of the Wilshire technique to either abridged uniaxial data or to virgin or abridged punch test data. A complication with the small punch test, however, is that the recorded failure time is dependant not just on temperature and load (as in a uniaxial test) but also on the geometries of the specimen and the test rig (punch radian, disc diameter, disc thickness, clamp material etc). Clearly there is a need to minimise the impact of these variables on the test result (and so maximise the sensitivity to any pre-existing damage). To date there has been minimal research on what these geometries should be and how different clamp materials can effect residual stress present in the discs as a result of differing coefficients of expansions &#x2013; being confined mainly to numerical modelling. Furthermore, the results of the Small Punch creep test are shown by time/displacement curves which while appearing comparable to that of conventional uniaxial creep data, in reality the creep mechanism present in each test technique are quite unique. 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J.</supervisor><degreelevel>Doctoral</degreelevel><degreename>Ph.D</degreename><degreesponsorsfunders>EPSRC Doctoral Training Grant (EGF1050-100)</degreesponsorsfunders><apcterm/><funders/><projectreference/><lastEdited>2023-10-05T14:53:10.5993462</lastEdited><Created>2023-07-03T16:52:21.6135113</Created><path><level id="1">Faculty of Science and Engineering</level><level id="2">School of Engineering and Applied Sciences - Materials Science and Engineering</level></path><authors><author><firstname>THOMAS</firstname><surname>WILLIAMS</surname><order>1</order></author></authors><documents><document><filename>Under embargo</filename><originalFilename>Under embargo</originalFilename><uploaded>2023-07-03T16:56:40.2763355</uploaded><type>Output</type><contentLength>5916708</contentLength><contentType>application/pdf</contentType><version>Redacted version - open access</version><cronfaStatus>true</cronfaStatus><embargoDate>2028-06-20T00:00:00.0000000</embargoDate><documentNotes>Copyright: The Author, Thomas Williams, 2023.</documentNotes><copyrightCorrect>true</copyrightCorrect><language>eng</language></document></documents><OutputDurs/></rfc1807>
spelling 2023-10-05T14:53:10.5993462 v2 63768 2023-07-03 Life Assessment based on the Small Punch Test and the Wilshire Equations 5278d5df2722d473663a274ec43e37df THOMAS WILLIAMS THOMAS WILLIAMS true false 2023-07-03 Uniaxial creep data plays a key role in predicting the life cycle of different alloys and parts present in power generation and aero engines, such as RR1000 which is used in turbine disc components. Modern studies have found success in using the Wilshire equations as a creep lifing method, making it possible to obtain long term life predictions, up to 100,000 hours, from short accelerated uniaxial tests typically lasting up to 5000 hours. Improvements in extrapolative ability can be achieved by uniaxial testing, at accelerated temperatures but operational stresses (or visa versa), utilising specimens cut from components that have not yet failed but have been in service for long periods of time. The shorter residual lives then require less extrapolation with respect to stress or temperature - but creating such test specimens leads to component destruction which is very costly. To further build on the idea behind abridged testing, the small punch test has been developed to produce data from service parts in power plants without compromising the ongoing structural strength of the component. This is achieved by obtaining thin slices of material from component and then applying a constant load - via a punch – to a machined disc. However, there has been little application of the Wilshire technique to either abridged uniaxial data or to virgin or abridged punch test data. A complication with the small punch test, however, is that the recorded failure time is dependant not just on temperature and load (as in a uniaxial test) but also on the geometries of the specimen and the test rig (punch radian, disc diameter, disc thickness, clamp material etc). Clearly there is a need to minimise the impact of these variables on the test result (and so maximise the sensitivity to any pre-existing damage). To date there has been minimal research on what these geometries should be and how different clamp materials can effect residual stress present in the discs as a result of differing coefficients of expansions – being confined mainly to numerical modelling. Furthermore, the results of the Small Punch creep test are shown by time/displacement curves which while appearing comparable to that of conventional uniaxial creep data, in reality the creep mechanism present in each test technique are quite unique. Therefore data obtained from Small Punch Creep (SPC) tests cannot be used to find or to compare to the values of conventional creep parameters, hence the need for a form of correlation to bridge the gap between the two test types. E-Thesis Swansea, Wales, UK Creep, Small Punch Creep, Creep Lifing, Nickel Superalloy, Wilshire Equation 15 6 2023 2023-06-15 10.23889/SUthesis.63768 A selection of third party content is redacted or is partially redacted from this thesis due to copyright restrictions. COLLEGE NANME COLLEGE CODE Swansea University Evans, Mark. and Williams, S. J. Doctoral Ph.D EPSRC Doctoral Training Grant (EGF1050-100) 2023-10-05T14:53:10.5993462 2023-07-03T16:52:21.6135113 Faculty of Science and Engineering School of Engineering and Applied Sciences - Materials Science and Engineering THOMAS WILLIAMS 1 Under embargo Under embargo 2023-07-03T16:56:40.2763355 Output 5916708 application/pdf Redacted version - open access true 2028-06-20T00:00:00.0000000 Copyright: The Author, Thomas Williams, 2023. true eng
title Life Assessment based on the Small Punch Test and the Wilshire Equations
spellingShingle Life Assessment based on the Small Punch Test and the Wilshire Equations
THOMAS WILLIAMS
title_short Life Assessment based on the Small Punch Test and the Wilshire Equations
title_full Life Assessment based on the Small Punch Test and the Wilshire Equations
title_fullStr Life Assessment based on the Small Punch Test and the Wilshire Equations
title_full_unstemmed Life Assessment based on the Small Punch Test and the Wilshire Equations
title_sort Life Assessment based on the Small Punch Test and the Wilshire Equations
author_id_str_mv 5278d5df2722d473663a274ec43e37df
author_id_fullname_str_mv 5278d5df2722d473663a274ec43e37df_***_THOMAS WILLIAMS
author THOMAS WILLIAMS
author2 THOMAS WILLIAMS
format E-Thesis
publishDate 2023
institution Swansea University
doi_str_mv 10.23889/SUthesis.63768
college_str Faculty of Science and Engineering
hierarchytype
hierarchy_top_id facultyofscienceandengineering
hierarchy_top_title Faculty of Science and Engineering
hierarchy_parent_id facultyofscienceandengineering
hierarchy_parent_title Faculty of Science and Engineering
department_str School of Engineering and Applied Sciences - Materials Science and Engineering{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Engineering and Applied Sciences - Materials Science and Engineering
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description Uniaxial creep data plays a key role in predicting the life cycle of different alloys and parts present in power generation and aero engines, such as RR1000 which is used in turbine disc components. Modern studies have found success in using the Wilshire equations as a creep lifing method, making it possible to obtain long term life predictions, up to 100,000 hours, from short accelerated uniaxial tests typically lasting up to 5000 hours. Improvements in extrapolative ability can be achieved by uniaxial testing, at accelerated temperatures but operational stresses (or visa versa), utilising specimens cut from components that have not yet failed but have been in service for long periods of time. The shorter residual lives then require less extrapolation with respect to stress or temperature - but creating such test specimens leads to component destruction which is very costly. To further build on the idea behind abridged testing, the small punch test has been developed to produce data from service parts in power plants without compromising the ongoing structural strength of the component. This is achieved by obtaining thin slices of material from component and then applying a constant load - via a punch – to a machined disc. However, there has been little application of the Wilshire technique to either abridged uniaxial data or to virgin or abridged punch test data. A complication with the small punch test, however, is that the recorded failure time is dependant not just on temperature and load (as in a uniaxial test) but also on the geometries of the specimen and the test rig (punch radian, disc diameter, disc thickness, clamp material etc). Clearly there is a need to minimise the impact of these variables on the test result (and so maximise the sensitivity to any pre-existing damage). To date there has been minimal research on what these geometries should be and how different clamp materials can effect residual stress present in the discs as a result of differing coefficients of expansions – being confined mainly to numerical modelling. Furthermore, the results of the Small Punch creep test are shown by time/displacement curves which while appearing comparable to that of conventional uniaxial creep data, in reality the creep mechanism present in each test technique are quite unique. Therefore data obtained from Small Punch Creep (SPC) tests cannot be used to find or to compare to the values of conventional creep parameters, hence the need for a form of correlation to bridge the gap between the two test types.
published_date 2023-06-15T05:12:18Z
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score 11.109323

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