中文摘要：

伴随结构精细化、小型化的发展,薄板、薄壁管件等小尺寸构件得到应用,试样小型化对满足特殊取样要求和材料断裂韧度测试需求有重要工程意义,而基于非标小试样的材料断裂性能测试方法尚难满足需求。设计用于延性材料断裂韧度测试的C形环小试样,提出应用该类小尺寸试样获取材料延性断裂韧度的、基于量纲一载荷分离理论的规则化测试方法。分别采用C形环小试样和传统紧凑拉伸型（Compact tension,CT）大试样完成转子材料26Ni Cr Mo V11-5钢和压力容器材料A508-Ⅲ钢的J阻力曲线试验,讨论C形环小试样厚度、初始裂纹长度对试验结果的影响。结果表明,试样厚度和初始裂纹长度对C形环的J阻力曲线测试结果影响有限,但C形环试样裂尖具有更高的约束水平,由C形环试样得到的J阻力曲线明显低于CT试样的结果。

英文摘要：

With the miniaturization development of engineering components, thin plates and thin-walled tubes are widely applied in the industries of aerospace, nuclear power, chemical equipment and instrumentation, the estimation of fracture toughness by using small size specimens is of great importance for special demand of sampling and testing, but the current test method for the fracture properties of materials with small specimen is far from demands. A small size C-ring specimen is designed for determining fracture toughness of ductile materials and a new non-dimensional load separation method to estimate J-resistance curves of ductile materials for the C-ring specimen is proposed. J-resistance curves tests for 26NiCrMoV11-5 and A508-III are carried out by use of C-ring specimens and compact tension（CT） specimens, respectively. The results show that, the specimen thickness and initial crack size have limited influence on fracture toughness of ductile materials obtained by C-ring specimens. Due to the higher level of constraint near the crack tip of the C-ring specimens, visible lower J-resistance curves can be observed in comparison the results of the CT specimens.