J-integral has served as a powerful tool in characterizing crack tip status. The main feature, i.e. path- independence, makes it one of the foremost fracture parameters. In order to remain the path- independence for f...J-integral has served as a powerful tool in characterizing crack tip status. The main feature, i.e. path- independence, makes it one of the foremost fracture parameters. In order to remain the path- independence for fluid-driven cracks, J-integral is revised. In this paper, we present an extended J-in- tegral explicitly for fluid-driven cracks, e.g. hydraulically induced fractures in petroleum reservoirs, for three-dimensional （3D） problems. Particularly, point-wise 3D extended J-integral is proposed to char- acterize the state of a point along crack front. Besides, applications of the extended J-integral to porous media and thermally induced stress conditions are explored. Numerical results show that the extended J- integral is indeed path-independent, and they are in good agreement with those of equivalent domain integral under linear elastic and elastoplastic conditions. In addition, two distance-independent circular integrals in the K-dominance zone are established, which can be used to calculate the stress intensity factor （SIF）.展开更多
In this paper, by means of the maximum circle tensile stress on curve of constant ω and stress intensity factors by a path independent contour integral method, trajectories of maxed mode crack propagation are simulat...In this paper, by means of the maximum circle tensile stress on curve of constant ω and stress intensity factors by a path independent contour integral method, trajectories of maxed mode crack propagation are simulated through numerical manifold method. The crack propagation is traced dynamically by modifying the neighboring connection between the crack-top and nodes within elements in the calculating process. This method has the advantages such as less modified area, easiness of programming, high realizability and so on. Then a single sharp nicked specimen is used to verified the numerical result. It is shown that the provided method is reasonable and effective.展开更多
钝化线是描述裂纹试样在钝化过程中J积分与伸张区宽度(stretch zone width,SZW)间关系的一条直线,在J积分测试中,有效数据区的左右界限线以及确定延性断裂韧度JⅠC的偏置线都是建立在钝化线基础上的,因而钝化线在J积分测试中至关重要。...钝化线是描述裂纹试样在钝化过程中J积分与伸张区宽度(stretch zone width,SZW)间关系的一条直线,在J积分测试中,有效数据区的左右界限线以及确定延性断裂韧度JⅠC的偏置线都是建立在钝化线基础上的,因而钝化线在J积分测试中至关重要。通过对裂尖钝化过程的分析,基于D-B模型和J积分的路径无关性原理推导出一种钝化线方程。与现行标准中的钝化线相比,此方程与试验结果吻合得更好。展开更多
文摘J-integral has served as a powerful tool in characterizing crack tip status. The main feature, i.e. path- independence, makes it one of the foremost fracture parameters. In order to remain the path- independence for fluid-driven cracks, J-integral is revised. In this paper, we present an extended J-in- tegral explicitly for fluid-driven cracks, e.g. hydraulically induced fractures in petroleum reservoirs, for three-dimensional （3D） problems. Particularly, point-wise 3D extended J-integral is proposed to char- acterize the state of a point along crack front. Besides, applications of the extended J-integral to porous media and thermally induced stress conditions are explored. Numerical results show that the extended J- integral is indeed path-independent, and they are in good agreement with those of equivalent domain integral under linear elastic and elastoplastic conditions. In addition, two distance-independent circular integrals in the K-dominance zone are established, which can be used to calculate the stress intensity factor （SIF）.
基金Funded by the National Natural Science Foundation of China (No. 10272033) and Guangdong Provincial Natural Science Foundation(Nos.04105386,5300090 and 05001844).
文摘In this paper, by means of the maximum circle tensile stress on curve of constant ω and stress intensity factors by a path independent contour integral method, trajectories of maxed mode crack propagation are simulated through numerical manifold method. The crack propagation is traced dynamically by modifying the neighboring connection between the crack-top and nodes within elements in the calculating process. This method has the advantages such as less modified area, easiness of programming, high realizability and so on. Then a single sharp nicked specimen is used to verified the numerical result. It is shown that the provided method is reasonable and effective.
文摘钝化线是描述裂纹试样在钝化过程中J积分与伸张区宽度(stretch zone width,SZW)间关系的一条直线,在J积分测试中,有效数据区的左右界限线以及确定延性断裂韧度JⅠC的偏置线都是建立在钝化线基础上的,因而钝化线在J积分测试中至关重要。通过对裂尖钝化过程的分析,基于D-B模型和J积分的路径无关性原理推导出一种钝化线方程。与现行标准中的钝化线相比,此方程与试验结果吻合得更好。
