CAJ | 학술논문

通过使用基于内聚力模型（CZM ）的扩展有限元方法（XFEM ）对单边切口梁的三点弯曲试验进行数值模拟来研究核级石墨IG-11断裂韧性的尺寸效应，试验和分析中考虑了试样整体尺寸和厚度变化，并对数值分析中的材料断裂参数进行了敏感性研究。模拟所得断裂韧性范围为0.90～1.10 M Pa · m1/2，这与试验所测得的0.82～1.27 M Pa · m1/2接近。模拟结果表明，材料断裂功对数值分析的影响较小，而材料断裂时的抗拉强度对数值分析的影响较大；另外，核石墨的断裂韧性（KIC ）存在明显的尺寸效应，随模拟试样整体尺寸的增大，断裂韧性增大，最终趋于一定值。这与现有文献中的尺寸效应模型所得到的预测值以及试验结果吻合得较好。但试样厚度则对 KIC的变化无明显影响。
통과사용기우내취력모형（CZM ）적확전유한원방법（XFEM ）대단변절구량적삼점만곡시험진행수치모의래연구핵급석묵IG-11단렬인성적척촌효응，시험화분석중고필료시양정체척촌화후도변화，병대수치분석중적재료단렬삼수진행료민감성연구。모의소득단렬인성범위위0.90～1.10 M Pa · m1/2，저여시험소측득적0.82～1.27 M Pa · m1/2접근。모의결과표명，재료단렬공대수치분석적영향교소，이재료단렬시적항랍강도대수치분석적영향교대；령외，핵석묵적단렬인성（KIC ）존재명현적척촌효응，수모의시양정체척촌적증대，단렬인성증대，최종추우일정치。저여현유문헌중적척촌효응모형소득도적예측치이급시험결과문합득교호。단시양후도칙대 KIC적변화무명현영향。
The study of size effect on the fracture toughness of nuclear grade graphite IG-11 by using extended finite element method (XFEM ) which is based on the cohesive zone model (CZM ) to simulate the fracture of single-edge-notched beams under three-point-bending was carried out .The influence of specimen size and thickness was studied both in the experiment and the simulation .Besides ,sensitivity analysis of the fracture parameters was under consideration in the numerical analysis . The predicted fracture toughness is in a range of 0.90-1.10 M Pa · m1/2 which is close to the experiment result of 0.82-1.27 M Pa · m1/2 .And the simulation results show that crack initiation strength has greater influence on the numerical analysis than the fracture energy of the material . In addition ,the fracture toughness of nuclear graphite shows a size effect ,i.e.the frac-ture toughness increases as the specimen size increases and finally converges to a con-stant value ,which agrees with the experiment and the prediction from recent size effect model as well .However ,the specimen thickness has no obvious effect on KIC .