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工程中常用的评价管节点疲劳寿命的方法是使用S-N曲线。当管节点承受疲劳荷载作用的时候,可以通过数值方法得到沿着焊缝处的热点应力幅的大小。采用有限元软件ANSYS计算了宿淮铁路京杭运河特大桥的H3横撑T形管节点在轴向力、平面内弯矩以及平面外弯矩作用下的热点应力,根据相关计算方法得出节点处应力集中系数以及支管和弦管应力集中系数的分布,通过计算发现,最大应力集中系数出现在支管,说明在疲劳荷载作用下,支管会先破坏。然后通过S-N曲线,可以预测此节点在破坏前可以承受疲劳载荷的循环次数。
The commonly used method to evaluate the fatigue life of tube joints in engineering is to use the S-N curve. When the tube joints are subjected to the fatigue load, the magnitude of the thermal stress amplitude along the welds can be obtained numerically. Using the finite element software ANSYS, the hot spot stress of the T-shaped cross-section T-tube joints of the Beijing-Hangzhou Grand Canal on the Su-Huai Railway bridge under axial force, in-plane bending moment and out of plane bending moment was calculated. According to the relevant calculation method, Stress concentration factor and the distribution of stress concentration coefficient of the branch chord tube. The maximum stress concentration factor is found in the branch pipe by calculation, indicating that the branch pipe will be destroyed first under the fatigue load. Then through the S-N curve, we can predict the number of cycles this node can withstand the fatigue load before failure.