TESTING METHOD STUDY ON FATIGUE CRACK PROPAGATION BEHAVIOR OF CRO SPECIMEN

Recognizing the large size requirement and high cost associated with the test of the standard specimens such as compact tension (CT) and single edged notched bending (SEB) specimen, a testing method for fatigue crack propagation of small size C-ring specimen with an outer radial crack (CRO) has been developed. With finite element analyses, expressions of stress intensity factor and crack length based on compliance principle were established with good accuracy. A type of 5083-H112 aluminum alloy was employed to complete the tests of fatigue crack growth rate by using CRO and CT specimens, respectively. Correspondingly, the power exponent of Paris equation of the two types of specimens were also obtained. The comparison shows that the fatigue crack propagation behaviors of CRO and CT specimens are similar, implying that the new method is valid and effective. Based on the above method, the fatigue crack propagation of two CRO samples of C250 steel with different thicknesses has been studied.