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BAY - LOGI. 2 nd Hungarian-Ukrainian Joint Conference on SAFETY-RELIABILITY AND RISK OF ENGINEERING PLANTS AND COMPONENTS ASSESSMENT OF SUB-CLAD FLAWS, J-INTEGRAL CALCULATION. Róbert Beleznai Tibor Köves Péter Kavalyecz. Bay Zoltán Foundation for Applied Research

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R bert beleznai tibor k ves p ter kavalyecz

BAY-LOGI

2nd Hungarian-Ukrainian Joint Conferenceon SAFETY-RELIABILITY AND RISK OF ENGINEERING PLANTS AND COMPONENTSASSESSMENT OF SUB-CLAD FLAWS, J-INTEGRAL CALCULATION

Róbert Beleznai

Tibor Köves

Péter Kavalyecz

Bay Zoltán Foundation for Applied Research

Institute for Logistic and Production Systems

Kyiv

20th September, 2007


Content

BAY-LOGI

CONTENT

  • Test specimens

    • Crack type

    • Crack dimensions

    • Crack geometry

  • Material properties

  • Residual stress

  • Validation of the model

  • Boundary condition

  • J-integral calculation

2nd Hungarian-Ukrainian Joint Conference – Kyiv, 2007


BAY-LOGI

Introduction

Main objective of the work

  • WWER Cladded Reactor Pressure Vessel (WWER-440)J-integral calculation based on the report of the Nuclear Research Institute Rez plc, Division of Integrity and Technical Engineering.

2nd Hungarian-Ukrainian Joint Conference – Kyiv, 2007


Test specimen

BAY-LOGI

Test specimen

  • Specimen type: 4PB(40x85x670 mm)

2nd Hungarian-Ukrainian Joint Conference – Kyiv, 2007


Material properties

BAY-LOGI

Material properties

  • WWER reactor pressure vessel steel with austenitic cladding

  • Data arises from the report of the NRI

  • True stress – true plastic strain curve was derived for the FE calculation

2nd Hungarian-Ukrainian Joint Conference – Kyiv, 2007


Material properties1

BAY-LOGI

Material properties

Poisson ratio: =0.3

E=162 GPa

=17.1*10-6

E=211 GPa

=12.55*10-6

2nd Hungarian-Ukrainian Joint Conference – Kyiv, 2007


Crack type s

BAY-LOGI

Crack types

  • Two different crack lengths were analyzed

  • 1e2 and 1e4:

    • crack length: 15 mm

    • upper cracktip located 3 mm under the fusion line of the cladding

    • both crack tips are sharp

  • 1e7:

    • crack length: 40 mm

    • upper cracktip located 3 mm under the fusion line of the cladding

    • upper crack tip is sharp

    • lower crack tip is drilled out

2nd Hungarian-Ukrainian Joint Conference – Kyiv, 2007


Crack dimensions

BAY-LOGI

Crack dimensions

Straight crack front were considered in all case.

2nd Hungarian-Ukrainian Joint Conference – Kyiv, 2007


Crack g eometry

BAY-LOGI

Crack geometry

2nd Hungarian-Ukrainian Joint Conference – Kyiv, 2007


Residual stress

BAY-LOGI

Residual stress

  • Residual stress arises from the difference of the thermal expansion coefficients

  • Stress free temperature: Tsf=350°C

2nd Hungarian-Ukrainian Joint Conference – Kyiv, 2007


Residual stress1

BAY-LOGI

Residual stress

Comp 11 of stress

2nd Hungarian-Ukrainian Joint Conference – Kyiv, 2007


Residual stress2

BAY-LOGI

Residual stress

2nd Hungarian-Ukrainian Joint Conference – Kyiv, 2007


Validation of the fe model

BAY-LOGI

Validation of the FE model

2nd Hungarian-Ukrainian Joint Conference – Kyiv, 2007


BAY-LOGI

NRI

BZF

The results of NRI and BZF are in very good correlation.

2nd Hungarian-Ukrainian Joint Conference – Kyiv, 2007


Load displacement curves

BAY-LOGI

Load-displacement curves

2nd Hungarian-Ukrainian Joint Conference – Kyiv, 2007


Fe model

BAY-LOGI

FE model

  • MSC.MARC 2005R3 code

  • 3D model

  • 20 nodes hexahedron elements

  • J-integral calculation

2nd Hungarian-Ukrainian Joint Conference – Kyiv, 2007


Boundary conditions

BAY-LOGI

Boundary conditions

Only one quarter of the specimen was simulated.

Symmetry condition

Total applied force

2

Total applied force

2

2nd Hungarian-Ukrainian Joint Conference – Kyiv, 2007


J integral calculation

Straight crack front

BAY-LOGI

J-integral calculation

J-integral values along the crack front at max loading

2nd Hungarian-Ukrainian Joint Conference – Kyiv, 2007


J integral calculation1

Straight crack front

BAY-LOGI

J-integral calculation

J-integral valueshistory plot

2nd Hungarian-Ukrainian Joint Conference – Kyiv, 2007


Real crack front

1E7

1E4

1E2

BAY-LOGI

Real crack front

2nd Hungarian-Ukrainian Joint Conference – Kyiv, 2007


J integral along the crack front

Real crack front

BAY-LOGI

J-integral along the crack front

2nd Hungarian-Ukrainian Joint Conference – Kyiv, 2007


J integral history plot

Real crack front

BAY-LOGI

J-integral history plot

J-integral valueshistory plot

2nd Hungarian-Ukrainian Joint Conference – Kyiv, 2007


Conclusion

BAY-LOGI

Conclusion

  • In case of short straight and short real cracks the difference of the J-integral values is not significant.

  • In case of deep crack more accurate J-integral value was resulted, if real crack front was modelled.

  • Residual stress was considered, and this calculation is validated by NRI data.

  • FE models were also validated by LLD curve of NRI.

2nd Hungarian-Ukrainian Joint Conference – Kyiv, 2007


Possibilities for further investigations

BAY-LOGI

Possibilities for further investigations

  • Weibull stress calculation based on the Beremin-model.

  • T-stress calculation.

2nd Hungarian-Ukrainian Joint Conference – Kyiv, 2007


Thank you for your kind attention

BAY-LOGI

Thank you for your kind attention!

2nd Hungarian-Ukrainian Joint Conference – Kyiv, 2007


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