CAJ | 학술논문

针对输油管道中检测出的表面裂纹提出了在测量沿着裂纹表面的开口方向位移分布的基础上，通过计算裂纹周围的应力分布，评价裂纹端部应力强度因子Kest的方法。通过有限元解析对不同深长比（c／a）的表面裂纹，对在各种载荷作用下的应力强度因子KFEM进行了评价。并与传统的New-man－Raju公式对同样裂纹计算的相应应力强度因子K进行了比较。其结果是KFEM与K的结果基本相同。说明了本评价方法的可靠性。通过实验研究了表面裂纹初始疲劳扩展过程中裂纹端部应力强度因子Kest ，结果表明对实际输油管道中存在的表面裂纹，即使载荷、裂纹深度未知及裂纹周围有残余压缩应力存在的情况下，本文提出的应力强度因子的评价方法仍然有效。
침대수유관도중검측출적표면렬문제출료재측량연착렬문표면적개구방향위이분포적기출상，통과계산렬문주위적응력분포，평개렬문단부응력강도인자Kest적방법。통과유한원해석대불동심장비（c／a）적표면렬문，대재각충재하작용하적응력강도인자KFEM진행료평개。병여전통적New-man－Raju공식대동양렬문계산적상응응력강도인자K진행료비교。기결과시KFEM여K적결과기본상동。설명료본평개방법적가고성。통과실험연구료표면렬문초시피로확전과정중렬문단부응력강도인자Kest ，결과표명대실제수유관도중존재적표면렬문，즉사재하、렬문심도미지급렬문주위유잔여압축응력존재적정황하，본문제출적응력강도인자적평개방법잉연유효。
For surface-cracks detected from oil pipe -lines, a method to evaluate the stress intensity factor Kest was suggested by measuring the opening displacement distribution along the crack and calculating stress distributions around it .The stress intensity factor KFEM was e-valuated by FEM analysis for different ratio of c/a subjecting various loading .The value of KFEM was compared with K calculated by Newman-Raju’s conventional equation.The stress intensity factors KFEM and K were good agreement for all cracks .That is to say, the method suggested in this paper to evaluate the stress intensity factors is reliable .The stress intensity factor Kest for initial fatigue growth of surface -crack was studied by experiment .As a result, this suggesting method was also efficacious for the surface -cracks with residual stress detec-ted from oil pipe-lines, even though the loading applied to the surface crack and the depth of it are unknown .