광범위 크리프 조건에 대한 관통균열 배관의 크리프 파괴역학 해석

Abstract

This paper compares engineering estimation schemes of C^* and creep COD for circumferential and axial through-wall cracked pipes at elevated temperatures with detailed 3-D elastic-creep finite element results. Engineering estimation schemes included the GE/EPRI method, the reference stress method where reference stress is defined based on the plastic limit load and the enhanced reference stress method where the reference stress is defined based on the optimized reference load. Systematic investigations are made not only on the effect of creep-deformation behaviour on C^* and creep COD, but also on effects of the crack location. the pipe geometry, the crack length and the loading mode. Comparison of the FE results with engineering estimations provides that for idealized power law creep. estimated C^* and COD rate results from the GE/EPRI method agree best with FE results. For general creep-deformation laws where eit her primary or tertiary creep is important and thus the GE/EPRI method is hard to apply, on the other hand, the enhanced reference stress method provides more accurate and robust estimations for C^* and COD rate than the reference stress method.