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On the Plastic Strain Accumulation in Notched Bars During High-Temperature Creep Dwell

Published online by Cambridge University Press:  21 February 2020

Daniele Barbera  and
Haofeng Chen
Daniele Barbera
Affiliation:
School of Engineering, System, Power and Energy Division, University of Glasgow, Glasgow, UK
Haofeng Chen*
Affiliation:
Department of Mechanical & Aerospace Engineering, University of Strathclyde, Glasgow, UK
*
*Corresponding author (haofeng.chen@strath.ac.uk)
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Abstract

Structural integrity plays an important role in any industrial activity, due to its capability of assessing complex systems against sudden and unpredicted failures. The work here presented investigates an unexpected new mechanism occurring in structures subjected to monotonic and cyclic loading at high temperature creep condition. An unexpected accumulation of plastic strain is observed to occur, within the high-temperature creep dwell. This phenomenon has been observed during several full inelastic finite element analyses. In order to understand which parameters make possible such behaviour, an extensive numerical study has been undertaken on two different notched bars. The notched bar has been selected due to its capability of representing a multiaxial stress state, which is a practical situation in real components. Two numerical examples consisting of an axisymmetric v-notch bar and a semi-circular notched bar are considered, in order to investigate different notches severity. Two material models have been considered for the plastic response, which is modelled by both Elastic-Perfectly Plastic and Armstrong-Frederick kinematic hardening material models. The high-temperature creep behaviour is introduced using the time hardening law. To study the problem several results are presented, as the effect of the material model on the plastic strain accumulation, the effect of the notch severity and the mesh element type and sensitivity. All the findings further confirm that the phenomenon observed is not an artefact but a real mechanism, which needs to be considered when assessing off-design condition. Moreover, it might be extremely dangerous if the cyclic loading condition occurs at such a high loading level.

Keywords

PlasticityCreepStructural Integrity
Type
Research Article
Information
Journal of Mechanics , Volume 36 , Issue 2 , April 2020 , pp. 167 - 176
Copyright
Copyright © 2020 The Society of Theoretical and Applied Mechanics

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References

REFERENCES

EDF Energy, Assessment procedure for the high temperature response of structures, R5 Issue 3. (2014)Google Scholar
The American Society of Mechanical Engineers, ASME boiler & pressure vessel code : an international code. Division 1 - Subsection NH. (2013)Google Scholar
Isobe, N., Yashirodai, K., and Murata, K.i.. Creep Damage Assessment Considering Stress Multiaxiality for Notched Specimens of a CrMoV Steel. ICMFF10. (2015)Google Scholar
Wen, J.-F. and Tu, S.-T., A multiaxial creep-damage model for creep crack growth considering cavity growth and microcrack interaction. Engineering Fracture Mechanics. 123: p. 197–210. (2014)CrossRefGoogle Scholar
Goyal, S., Laha, K., and Mathew, M.D., Creep Life Prediction of Modified 9Cr-1Mo Steel under Multiaxial State of Stress. Procedia Engineering. 86: p. 150–157. (2014)CrossRefGoogle Scholar
Sauzay, M., et al., Creep-fatigue behaviour of an AISI stainless steel at 550 °C. Nuclear Engineering and Design. 232(3): p. 219–236. (2004)CrossRefGoogle Scholar
Dyson, B., Use of CDM in materials modeling and component creep life prediction. Journal of pressure vessel technology. 122(3): p. 281–296. (2000)CrossRefGoogle Scholar
Kachanov, L.M., Rupture time under creep conditions. International journal of fracture. 97(1-4): p. 11–18. (1999)CrossRefGoogle Scholar
Rabotnov, I.N., Creep problems in structural members. English translation edited by Leckie, F.A.. North-Holland series in applied mathematics and mechanics, v. 7 (1969)Google Scholar
Liu, Y. and Murakami, S., Damage Localization of Conventional Creep Damage Models and Proposition of a New Model for Creep Damage Analysis. JSME International Journal Series A. 41(1): p. 57–65. (1998)CrossRefGoogle Scholar
Hyde, T.H., Saber, M., and Sun, W., Creep crack growth data and prediction for a P91 weld at 650 °C. International Journal of Pressure Vessels and Piping. 87(12): p. 721–729. (2010)CrossRefGoogle Scholar
Hyde, C.J., et al., Application of the Liu and Murakami Damage Model for Creep Crack Growth Predictions in Power Plant Steels. Computational and Numerical Simulations, Chapter 9. (2014)Google Scholar
Hyde, T., Hyde, C., and Sun, W., Applied creep mechanics. McGraw-Hill Professional. (2013)Google Scholar
Wang, W. Z., Buhl, P., Klenk, A., & Liu, Y. Z.Study of creep-fatigue behavior in a 1000 MW rotor using a unified viscoplastic constitutive model with damage. International Journal of Damage Mechanics. 25(2), 178–202. (2016)CrossRefGoogle Scholar
Holdsworth, S., Creep-Fatigue Failure Diagnosis. Materials. 8(11): p. 5418. (2015)CrossRefGoogle ScholarPubMed
Holdsworth, Stuart R., Mazza, Edoardo, and Jung, Arnd. “Creep-fatigue damage development during service-cycle thermo-mechanical fatigue tests of 1CrMoV rotor steel.” Proc. 9th International Conference on The Mechanical Behavior of Materials, Geneva, Switzerland. (2003)Google Scholar
Barbera, Daniele, Chen, Haofeng, and Liu, Yinghua. “Advances on creep-fatigue damage assessment in notched components.” Fatigue & Fracture of Engineering Materials & Structures. 40(11): 1854–1867. (2017)CrossRefGoogle Scholar
Chen, H., Chen, W., and Ure, J., A Direct Method on the Evaluation of Cyclic Steady State of Structures With Creep Effect. Journal of Pressure Vessel Technology, 136(6): p. 061404–061404. (2014)CrossRefGoogle Scholar
Gorash, Y. and Chen, H., Creep-fatigue life assessment of cruciform weldments using the linear matching method. International Journal of Pressure Vessels and Piping. 104(0): p. 1–13. (2013)CrossRefGoogle Scholar
Chen, H. and Ponter, A.R., Integrity assessment of a 3D tubeplate using the linear matching method. Part 2: Creep relaxation and reverse plasticity. International journal of pressure vessels and piping. 82(2): p. 95–104. (2005)CrossRefGoogle Scholar
Chaboche, J.-L. and Rousselier, G., On the plastic and viscoplastic constitutive equations—Part I: Rules developed with internal variable concept. Journal of Pressure Vessel Technology. 105(2): p. 153–158. (1983).CrossRefGoogle Scholar