Research on damage failure of TA18 titanium alloy based on stress triaxiality
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摘要: 对TA18钛合金材料设计不同缺口尺寸的拉伸试样,进行不同应力状态下的室温拉伸试验及断口形貌观察,通过试验和数值计算结合的方法研究TA18钛合金的韧性断裂特性,分析了应力状态对微观断裂机制的影响规律。利用Bridgman正向计算法修正颈缩失稳后的应力数据,建立了TA18钛合金的Johnson-Cook(J-C)本构模型,计算了拉伸试样的平均应力三轴度和断裂应变,回归确定了TA18钛合金损伤失效模型。结果表明:不同应力状态下的TA18钛合金断裂应变各不相同,断裂应变随着应力三轴度的增大而减小,断口韧窝尺寸与应力三轴度呈正相关关系,所建立的损伤失效模型能够描述该材料的断裂特性。Abstract: Tensile specimens made of TA18 titanium alloy with different notch sizes were designed to carry out tensile tests under different stress states at room temperature, and fracture morphology observation had been done. The ductile fracture characteristics of TA18 titanium alloy were studied through the combination of experiment and numerical calculation. The influence law of stress state on microscopic fracture mechanism had been analyzed. The Bridgman forward calculation method was used to correct the stress data after necking instability. The Johnson-Cook (JC) constitutive model of TA18 titanium alloy was established, and the average stress triaxiality and fracture strain of the tensile specimen were calculated and determined by the regression method. The damage failure model of TA18 titanium alloy is presented. The results show that the fracture strain of TA18 titanium alloy under different stress states is different. The fracture strain decreases with the increase of stress triaxiality, and the fracture dimple size is positively correlated with the stress triaxiality. The established damage failure model can explain the fracture characteristics of the material.
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Key words:
- TA18 titanium alloy /
- ductile fracture /
- stress triaxiality /
- damage failure /
- numerical simulation
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表 1 TA18钛合金的化学成分
Table 1. Chemical composition of TA18 titanium alloy
% Al V Fe C N O H Ti 2.75 2.5 0.25 0.08 0.05 0.12 0.015 余量 表 2 不同试样的断裂参数
Table 2. Fracture parameters of different samples
缺口半径/
mm初始直径/
mm断裂应变
εf断裂直径/
mm应力三轴度 初始值 最终值 平均值 1 4.20 0.452 3.35 0.670 1.330 1.136 2 4.15 0.520 3.2 0.628 1.152 1.047 3 4.10 0.625 3.0 0.596 1.030 0.941 -
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