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Research Papers: Design and Analysis

Using Nonlinear Kinematic Hardening Material Models for Elastic–Plastic Ratcheting Analysis

[+] Author and Article Information
Jürgen Rudolph

AREVA GmbH,
Henri-Dunant-Strasse 50,
Erlangen 91058, Germany
e-mail: rudolph.juergen@areva.com

Tim Gilman

Structural Integrity Associates, Inc.,
5215 Hellyer Avenue, Suite 210,
San Jose, CA 95138
e-mail: tgilman@structint.com

Bill Weitze

Structural Integrity Associates, Inc.,
5215 Hellyer Avenue, Suite 210,
San Jose, CA 95138
e-mail: wweitze@structint.com

Adrian Willuweit

AREVA GmbH,
Henri-Dunant-Strasse 50,
Erlangen 91058, Germany
e-mail: adrian.willuweit@areva.com

Arturs Kalnins

Emeritus Professor of Mechanics
Department of Mechanical Engineering
and Mechanics,
Lehigh University,
19 Memorial Drive West,
Bethlehem, PA 18015
e-mail: ak01@lehigh.edu

Contributed by the Pressure Vessel and Piping Division of ASME for publication in the JOURNAL OF PRESSURE VESSEL TECHNOLOGY. Manuscript received October 26, 2015; final manuscript received March 14, 2016; published online April 29, 2016. Assoc. Editor: David L. Rudland.

J. Pressure Vessel Technol 138(5), 051205 (Apr 29, 2016) (8 pages) Paper No: PVT-15-1231; doi: 10.1115/1.4033092 History: Received October 26, 2015; Revised March 14, 2016

Applicable design codes for power plant components and pressure vessels demand for a design check against progressive plastic deformation. In the simplest case, this demand is satisfied by compliance with shakedown rules in connection with elastic analyses. The possible noncompliance implicates the requirement of ratcheting analyses on elastic–plastic basis. In this case, criteria are specified on maximum allowable accumulated growth strain without clear guidance on what material models for cyclic plasticity are to be used. This is a considerable gap and a challenge for the practicing computer-aided engineering engineer. As a follow-up to two independent previous papers PVP2013-98150 ASME (Kalnins et al., 2013, “Using the Nonlinear Kinematic Hardening Material Model of Chaboche for Elastic-Plastic Ratcheting Analysis,” ASME Paper No. PVP2013-98150.) and PVP2014-28772 (Weitze and Gilman, 2014, “Additional Guidance for Inelastic Ratcheting Analysis Using the Chaboche Model,” ASME Paper No. PVP2014-28772.), it is the aim of this paper to close this gap by giving further detailed recommendation on the appropriate application of the nonlinear kinematic material model of Chaboche on an engineering scale and based on implementations already available within commercial finite element codes such as ANSYS® and ABAQUS®. Consistency of temperature-dependent runs in ANSYS® and ABAQUS® is to be checked. All three papers together constitute a comprehensive guideline for elastoplastic ratcheting analysis. The following issues are examined and/or referenced: (1) application of monotonic or cyclic material data for ratcheting analysis based on the Chaboche material model, (2) discussion of using monotonic and cyclic data for assessment of the (nonstabilized) cyclic deformation behavior, (3) number of backstress terms to be applied for consistent ratcheting results, (4) consideration of the temperature dependency (TD) of the relevant material parameters, (5) consistency of temperature-dependent runs in ANSYS® and ABAQUS®, (6) identification of material parameters dependent on the number of backstress terms, (7) identification of material data for different types of material (carbon steel, austenitic stainless steel) including the appropriate determination of the elastic limit, (8) quantification of conservatism of simple elastic-perfectly plastic (EPP) behavior, (9) application of engineering versus true stress–strain data, (10) visual checks of data input consistency, and (11) appropriate type of allowable accumulated growth strain. This way, a more accurate inelastic analysis methodology for direct practical application to real world examples in the framework of the design code conforming elastoplastic ratcheting check is proposed.

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References

Figures

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Fig. 1

Generic stress–plastic strain curve divided into M segments (Fig. 3.7 in Ref. [7])

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Fig. 2

Cyclic hardening curve [6]

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Fig. 3

Comparison of Backstress and Chaboche model, 70 °F (21.1 °C)

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Fig. 4

Comparison of Backstress and Chaboche model, 400 °F (204.4 °C)

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Fig. 11

Both models are run by accounting for TD of the material parameters (Ci and γi of Chaboche and yield stresses of EPP) of the support points at 21 °C and 204 °C

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Fig. 10

Both models are run with material parameters (Ci and γi of Chaboche and yield stress of EPP) at 204 °C

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Fig. 9

Stress–strain curve of a stainless steel

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Fig. 8

Comparison of the Ferritic curve with that by test

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Fig. 7

Stress–strain curve of a carbon steel

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Fig. 6

One-dimensional representation of hardening in the NLK model

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