A direct method for the evaluation of lower and upper bound ratchet limits

James Michael Ure, Haofeng Chen, Weihang Chen, Tianbai Li, James Tipping, Donald Mackenzie

Research output: Contribution to conferencePaper

8 Citations (Scopus)

Abstract

The calculation of the ratchet limit is often vital for the assessment of the design and integrity of components which are subject to cyclic loading. This work describes the addition of a lower bound calculation to the existing Linear
Matching Method upper bound ratchet analysis method. This lower bound calculation is based on Melan's theorem, and makes use of the residual and elastic stress fields calculated by the upper bound technique to calculate the lower bound ratchet limit multiplier. By doing this, the method combines the stable convergence of the upper bound method but retains the conservatism offered by the lower bound. These advantages are complemented by the ability of the Linear Matching Method to consider real 3D geometries subject to complex load histories including the effect of temperature dependent yield stress.
The convergence properties of this lower bound ratchet limit are investigated through a benchmark problem of a plate with a central hole subject to cyclic thermal and mechanical loads. To demonstrate the effectiveness of the method,
the ratchet limit of a thick walled pipe intersection, also subject to cyclic thermal and mechanical loads, is considered. Validation of these results is provided by full elastic-plastic FEA in Abaqus.

Conference

Conference11th International Conference on Mechanical Behaviour of Materials
CountryItaly
CityLake Como,
Period5/06/119/06/11

Fingerprint

Ratchet
Direct Method
Upper and Lower Bounds
Lower bound
Evaluation
Upper bound
Yield stress
Loads (forces)
Pipe
Stable Convergence
Plastics
Finite element method
Cyclic Loading
Geometry
Yield Stress
Stress Field
Convergence Properties
Integrity
Multiplier
Intersection

Keywords

  • ratchet limit
  • shakedown limit
  • lower and upper bound
  • cyclic loading

Cite this

Ure, J. M., Chen, H., Chen, W., Li, T., Tipping, J., & Mackenzie, D. (2011). A direct method for the evaluation of lower and upper bound ratchet limits. Paper presented at 11th International Conference on Mechanical Behaviour of Materials, Lake Como, Italy.
Ure, James Michael ; Chen, Haofeng ; Chen, Weihang ; Li, Tianbai ; Tipping, James ; Mackenzie, Donald. / A direct method for the evaluation of lower and upper bound ratchet limits. Paper presented at 11th International Conference on Mechanical Behaviour of Materials, Lake Como, Italy.6 p.
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Ure, JM, Chen, H, Chen, W, Li, T, Tipping, J & Mackenzie, D 2011, 'A direct method for the evaluation of lower and upper bound ratchet limits' Paper presented at 11th International Conference on Mechanical Behaviour of Materials, Lake Como, Italy, 5/06/11 - 9/06/11, .

A direct method for the evaluation of lower and upper bound ratchet limits. / Ure, James Michael; Chen, Haofeng; Chen, Weihang; Li, Tianbai; Tipping, James; Mackenzie, Donald.

2011. Paper presented at 11th International Conference on Mechanical Behaviour of Materials, Lake Como, Italy.

Research output: Contribution to conferencePaper

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AU - Tipping, James

AU - Mackenzie, Donald

PY - 2011/6/5

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N2 - The calculation of the ratchet limit is often vital for the assessment of the design and integrity of components which are subject to cyclic loading. This work describes the addition of a lower bound calculation to the existing LinearMatching Method upper bound ratchet analysis method. This lower bound calculation is based on Melan's theorem, and makes use of the residual and elastic stress fields calculated by the upper bound technique to calculate the lower bound ratchet limit multiplier. By doing this, the method combines the stable convergence of the upper bound method but retains the conservatism offered by the lower bound. These advantages are complemented by the ability of the Linear Matching Method to consider real 3D geometries subject to complex load histories including the effect of temperature dependent yield stress.The convergence properties of this lower bound ratchet limit are investigated through a benchmark problem of a plate with a central hole subject to cyclic thermal and mechanical loads. To demonstrate the effectiveness of the method,the ratchet limit of a thick walled pipe intersection, also subject to cyclic thermal and mechanical loads, is considered. Validation of these results is provided by full elastic-plastic FEA in Abaqus.

AB - The calculation of the ratchet limit is often vital for the assessment of the design and integrity of components which are subject to cyclic loading. This work describes the addition of a lower bound calculation to the existing LinearMatching Method upper bound ratchet analysis method. This lower bound calculation is based on Melan's theorem, and makes use of the residual and elastic stress fields calculated by the upper bound technique to calculate the lower bound ratchet limit multiplier. By doing this, the method combines the stable convergence of the upper bound method but retains the conservatism offered by the lower bound. These advantages are complemented by the ability of the Linear Matching Method to consider real 3D geometries subject to complex load histories including the effect of temperature dependent yield stress.The convergence properties of this lower bound ratchet limit are investigated through a benchmark problem of a plate with a central hole subject to cyclic thermal and mechanical loads. To demonstrate the effectiveness of the method,the ratchet limit of a thick walled pipe intersection, also subject to cyclic thermal and mechanical loads, is considered. Validation of these results is provided by full elastic-plastic FEA in Abaqus.

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Ure JM, Chen H, Chen W, Li T, Tipping J, Mackenzie D. A direct method for the evaluation of lower and upper bound ratchet limits. 2011. Paper presented at 11th International Conference on Mechanical Behaviour of Materials, Lake Como, Italy.