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Repeat stress relaxation of notched bars and the dependence of creep damage on relaxation rate

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Repeat stress relaxation of notched bars and the dependence of creep damage on relaxation rate. / Hares, Edward; Mostafavi, Mahmoud; Bradford, Richard; Truman, Chris.

In: International Journal of Pressure Vessels and Piping, Vol. 169, 01.01.2019, p. 115-124.

Research output: Contribution to journalArticle

Harvard

Hares, E, Mostafavi, M, Bradford, R & Truman, C 2019, 'Repeat stress relaxation of notched bars and the dependence of creep damage on relaxation rate', International Journal of Pressure Vessels and Piping, vol. 169, pp. 115-124. https://doi.org/10.1016/j.ijpvp.2018.12.003

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Author

Hares, Edward ; Mostafavi, Mahmoud ; Bradford, Richard ; Truman, Chris. / Repeat stress relaxation of notched bars and the dependence of creep damage on relaxation rate. In: International Journal of Pressure Vessels and Piping. 2019 ; Vol. 169. pp. 115-124.

Bibtex

@article{c42a401f7424404cbd97ff1ad0fd5ef2,
title = "Repeat stress relaxation of notched bars and the dependence of creep damage on relaxation rate",
abstract = "This paper aims to investigate whether creep strain accumulated at different strain rates is equally damaging. Previous research has suggested that creep strain is more damaging when accumulated more slowly in creep of notched bars. The research presented here seeks to address this question by considering the accumulation of creep strain during stress relaxation of notched bars, i.e. specimens which support an initial load in a displacement-controlled test which then relaxes through creep deformation. Repeat stress relaxation tests with varying dwell lengths were conducted so that the relative damaging effects of the early, rapid accumulation and later, slower accumulation of creep strains could be compared. The material used was an ex-service powerplant stainless steel Type 316H. The stresses and strains in the specimens were then assessed using finite element analysis; a user subroutine was implemented so the onset and propagation of creep damage could be simulated throughout the specimens’ creep life. The research showed that creep strain accumulated rapidly at the start of a dwell is significantly less damaging than the same creep strain accumulated more slowly towards the end of the dwell. Consistent with this, the creep strain which accumulated very rapidly during the reloading period appears to produce negligible damage.",
author = "Edward Hares and Mahmoud Mostafavi and Richard Bradford and Chris Truman",
year = "2019",
month = "1",
day = "1",
doi = "10.1016/j.ijpvp.2018.12.003",
language = "English",
volume = "169",
pages = "115--124",
journal = "International Journal of Pressure Vessels and Piping",
issn = "0308-0161",
publisher = "Elsevier",

}

RIS - suitable for import to EndNote

TY - JOUR

T1 - Repeat stress relaxation of notched bars and the dependence of creep damage on relaxation rate

AU - Hares, Edward

AU - Mostafavi, Mahmoud

AU - Bradford, Richard

AU - Truman, Chris

PY - 2019/1/1

Y1 - 2019/1/1

N2 - This paper aims to investigate whether creep strain accumulated at different strain rates is equally damaging. Previous research has suggested that creep strain is more damaging when accumulated more slowly in creep of notched bars. The research presented here seeks to address this question by considering the accumulation of creep strain during stress relaxation of notched bars, i.e. specimens which support an initial load in a displacement-controlled test which then relaxes through creep deformation. Repeat stress relaxation tests with varying dwell lengths were conducted so that the relative damaging effects of the early, rapid accumulation and later, slower accumulation of creep strains could be compared. The material used was an ex-service powerplant stainless steel Type 316H. The stresses and strains in the specimens were then assessed using finite element analysis; a user subroutine was implemented so the onset and propagation of creep damage could be simulated throughout the specimens’ creep life. The research showed that creep strain accumulated rapidly at the start of a dwell is significantly less damaging than the same creep strain accumulated more slowly towards the end of the dwell. Consistent with this, the creep strain which accumulated very rapidly during the reloading period appears to produce negligible damage.

AB - This paper aims to investigate whether creep strain accumulated at different strain rates is equally damaging. Previous research has suggested that creep strain is more damaging when accumulated more slowly in creep of notched bars. The research presented here seeks to address this question by considering the accumulation of creep strain during stress relaxation of notched bars, i.e. specimens which support an initial load in a displacement-controlled test which then relaxes through creep deformation. Repeat stress relaxation tests with varying dwell lengths were conducted so that the relative damaging effects of the early, rapid accumulation and later, slower accumulation of creep strains could be compared. The material used was an ex-service powerplant stainless steel Type 316H. The stresses and strains in the specimens were then assessed using finite element analysis; a user subroutine was implemented so the onset and propagation of creep damage could be simulated throughout the specimens’ creep life. The research showed that creep strain accumulated rapidly at the start of a dwell is significantly less damaging than the same creep strain accumulated more slowly towards the end of the dwell. Consistent with this, the creep strain which accumulated very rapidly during the reloading period appears to produce negligible damage.

UR - http://www.scopus.com/inward/record.url?scp=85058015105&partnerID=8YFLogxK

U2 - 10.1016/j.ijpvp.2018.12.003

DO - 10.1016/j.ijpvp.2018.12.003

M3 - Article

VL - 169

SP - 115

EP - 124

JO - International Journal of Pressure Vessels and Piping

JF - International Journal of Pressure Vessels and Piping

SN - 0308-0161

ER -