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用黏塑性有限元法模拟含中心裂纹试件在等幅循环拉伸加载和保载作用下的裂纹扩展规律.试件采用涡轮盘材料Udimet720 Li(low inclusion)、恒温700℃和平面应变假设,通过逐步释放裂纹尖端节点约束来模拟裂纹扩展.计算了在应力比R=0,不同最大循环载荷、不同保载时间对平面应变下无量纲裂纹张开应力强度因子的影响.平面应变情况下,无量纲裂纹张开应力强度因子随最大载荷的变化而趋于分散,并随着裂纹的扩展,会存在先上升后下降并趋于一个稳定值的趋势;载荷相同时,保载时间的增加使裂纹张开应力强度因子增加.高温保载情况下,蠕变会影响裂纹扩展速率.
The viscoelastic finite element method was used to simulate the crack growth of the specimens with central crack under constant amplitude cyclic loading and loading. The specimens were made of Udimet720 Li (low inclusions), constant temperature of 700 ℃ and plane strain assumption, The crack growth is modeled by the gradual release of the crack tip node constraint. The influence of stress relaxation ratio R = 0, different maximum cycle load and different loading time on the stress intensity factor of dimensionless crack under plane strain is calculated. Under plane strain, The dimensionless crack open stress intensity factor tends to disperse with the change of maximum load, and with the crack propagation, there exists a tendency of increasing firstly and then decreasing and tends to a stable value. When the load is the same, the loading time increases Crack open stress intensity factor increases.Carrying will affect the crack growth rate under high temperature loading conditions.