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Estimation of C*-Integral for Defective Components with General Creep-Deformation Behaviors

일반 크리프 거동을 고려한 균열 구조물 C*-적분 예측

  • Published : 2002.05.01

Abstract

For assessing significance of a defect in a component operating at high (creeping) temperatures, accurate estimation of fracture mechanics parameter, $C^{*}$-integral, is essential. Although the J estimation equation in the GE/EPRl handbook can be used to estimate the $C^{*}$-integral when the creep -deformation behavior can be characterized by the power law creep, such power law creep behavior is a very poor approximation for typical creep behaviors of most materials. Accordingly there can be a significant error in the $C^{*}$-integral. To overcome problems associated with GE/EPRl approach, the reference stress approach has been proposed, but the results can be sometimes unduly conservative. In this paper, a new method to estimate the $C^{*}$-integral for deflective components is proposed. This method improves the accuracy of the reference stress approach significantly. The proposed calculations are then validated against elastic -creep finite element (FE) analyses for four different cracked geometries following various creep -deformation constitutive laws. Comparison of the FE $C^{*}$-integral values with those calculated from the proposed method shows good agreements.greements.

Keywords

$C^{*}$-Integral;Creep;Generalized Creep Law;Reference Stress Approach;Enhanced Reference Stress Approach

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  1. Estimation of C(t) -Integral Under Transient Creep Conditions for a Cracked Pipe Subjected to Combined Mechanical and Thermal Loads Depending on Loading Conditions vol.35, pp.6, 2011, https://doi.org/10.3795/KSME-A.2011.35.6.609