钢桥疲劳裂纹钻孔止裂技术多孔布置方法研究

Research on multi-hole arrangement in stop-hole technology for retarding fatigue cracks in steel bridges

文章考虑双孔和附加孔2种多止裂孔布置,对开裂模型进行线弹性有限元分析,通过对比不同布置下模型的应力集中系数,研究多孔布置对于钻孔止裂法的影响。结果表明:双孔布置对应力集中的降低作用不如单止裂孔,但它会对疲劳裂纹的开展起到持续的抑制作用,在不能精确定位裂纹尖端时可以作为一种有效的备用方法;合理布置附加孔的直径与位置可以加强止裂孔的止裂修复效果,附加孔直径越大,与裂纹线间的垂直距离越小,效果越好;附加孔的最佳位置位于止裂孔前方,距离为止裂孔直径的1/4。

Two multi-hole arrangements, including double holes and additional holes, were discussed. The fracture model was analyzed by using finite element method. By comparing the stress concentra- tion factor（SCF） of different models, the influence of multi-hole arrangements on the stop-hole tech- nology was studied. The results show that the impact of double-hole arrangement on the r^eduction of SCF is smaller than that of single-hole arrangement. However, the double holes can provide continu- ous retardation on the crack propagation, which makes it an alternative method when the fatigue crack tip is not easily located. It is also shown that arranging the diameter and location of additional holes properly can make stop holes more effective. Bigger holes and closer distance to the crack tip can bring better results. The best location of additional holes is D/4 ahead of the crack tip.