貫通き裂開閉口挙動の3次元数値解析
2004 年 2004 巻 195 号 p. 253-262
詳細
2004 年 2004 巻 195 号 p. 253-262
In order to establish the calculation method of the fatigue crack opening stress level for the surface cracks in ship structural members, the validity of various crack-node release schemes and opening / closure stress definitions are investigated by 2- and 3-dimensional F.E. analysis of the crack closure behavior of a thickness-through crack. As results, followings are found;
1) The measured and calculated opening stresses defined by the compliance method agree well when the crack tip node is released at the maximum load and the element edge length at the crack tip is chosen so that it is about 1/10 the size of the plastic zone.
2) The variation of the crack propagation rate with the depth which gives a good account of the changing nature of the crack edge shape of a real thickness-through crack can be derived when the opening stress is defined as the remote stress at the time the compressive local stress at the crack tip node changes to a tensile stress.
3) It is advisable to define the opening stress by the sign change of the local stress at the crack tip whenKopis evaluated locally by 3-dimensional F.E. analysis.
