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对紧凑拉伸试样进行有限元分析,考察止裂孔边缘的应力分布情况,对比不同状况下裂纹尖端的力学特性,研究了孔径及附加孔对止裂效果的影响.结合钢桥面板局部模型实验,对开裂试件打孔止裂后进行疲劳实验,通过比较不同试件的疲劳寿命,对有限元分析结果进行了验证.分析和实验结果表明,经过止裂孔钻孔处理后,应力集中点位于试样预制裂纹直线延伸方向与止裂孔孔边缘相交处,相对于未打孔,裂纹尖端应力显著下降.裂纹尖端打孔止裂,能够提高构件疲劳寿命,且孔径越大,止裂效果越明显,孔径8mm以后,增大孔径所产生的止裂效果逐渐降低.不同孔径钻孔处理的疲劳试件,各阶段裂纹再次扩展速率相当,属于裂纹中速率扩展区,附加孔并没有影响裂纹扩展速率,但使疲劳寿命显著地提高.
The finite element analysis of the compact tensile specimen was conducted to investigate the stress distribution along the edge of the cracked hole and the mechanical properties of the crack tip were compared under different conditions to study the effect of the hole diameter and the additional hole on the crack arrest effect.According to the local model experiment , The fatigue test was carried out after the cracked specimens were cracked and cracked, the finite element analysis results were verified by comparing the fatigue life of different specimens.The analysis and experimental results show that, after the drilling of the cracked holes, the stress concentration point is located at The stress at the crack tip decreases obviously when the direction of straight line extension of the pre-crack and the edge of crack-arresting hole are not cracked, and the crack tip can be perforated and cracked to improve the fatigue life of the component, and the larger the crack size, the more obvious crack arrest effect , The crack arrest effect caused by the increase of the aperture is gradually reduced after the hole diameter is 8mm.Fatigue specimens with different hole diameters have the same re-expansion rate in each stage, which belongs to the medium rate expansion zone of crack, and the additional hole does not affect the crack growth rate , But the fatigue life is significantly improved.