Research on embedded crack propagation law of pressure vessel under fatigue loading

Abstract:

This paper mainly focuses on the problem that is difficult to determine the geometric shape change of embedded crack propagation in pressure vessels. The stress intensity factor of crack front is obtained by using the methods of Newman and Raju, and the relationships between depth and length changes of different cracks are obtained by combining with Paris formula. Meanwhile, by discretizing the elliptical crack tip into multiple points with equal distances and using the Simpson quadrature method, the geometric change relationships of the embedded cracks of pressure vessels with different materials are obtained under cyclic loading. The results show that under the action of tensile force, the fatigue growth of buried cracks tends to expand in the direction of the optimal expansion path. The larger the initial crack aspect ratio and the exponent m gives rise to the faster the speed of convergence to the optimal propagation path, namely, the faster tendency to form an approximate circle.