In this paper, the load interaction effect on fatigue crack growth under large scale yielding conditions is investigated, via combined experimental and finite element (FE) analyzes of a through-wall cracked pipe. For the fatigue load amplitude, two amplitudes were applied to the through-wall pipe, 75% and 85% of the experimental maximum load under monotonic loading. For the loading type, periodic overload, high-low and low-high loading sequences were applied. It is experimentally found that the change of crack growth rate due to load interaction does not occur under large scale yielding, in contrast to the behavior under small scale yielding. Numerical analysis using FE debond analysis further shows that crack closure does not occur in the through-wall cracked pipe under large scale yielding fatigue loading, which can explain no load interaction effect on fatigue crack growth, observed in the present experiment.

在本文中，通过对全壁裂纹管道进行联合实验和有限元 (FE) 分析，研究了载荷相互作用对大规模屈服条件下疲劳裂纹扩展的影响。对于疲劳载荷幅值，对穿壁管施加了两个幅值，分别为单调载荷下实验最大载荷的 75% 和 85%。对于加载类型，应用了周期性过载、高-低和低-高加载顺序。实验发现，与小规模屈服下的行为相反，在大规模屈服下不会发生由载荷相互作用引起的裂纹扩展速率的变化。使用有限元脱粘分析的数值分析进一步表明，在大规模屈服疲劳载荷下，穿壁裂纹管不会发生裂纹闭合，