Shear behaviors of hat-shaped high manganese steel specimens under high-speed impact
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摘要: 绝热剪切带是材料在高速变形时一种典型的破坏形式，为了更好地理解高速冲击过程中绝热剪切带的形成和扩展，基于Johnson-Cook本构模型，利用ANSYS/LS-DYNA软件对高锰钢帽型样品高速冲击过程的剪切行为进行了二维数值模拟。结果表明：横穿剪切带方向，应力应变分布都是剪切带中心最高，然后向两边逐渐降低，类似于高斯分布; 平行于剪切带方向，应力应变分布则是呈两端高中间低的特点。然后利用模拟的应力应变场分布确定了剪切带和裂纹形成及扩展方向，即从剪切区两端形成并向中间扩展；最后通过编辑软件的k文件直接得到了剪切带内部及周围形变影响区和基体的温度分布，其和应力应变场分布规律一致，结果与实验结果基本吻合。Abstract: Adiabatic shear band (ASB) is a typical failure mode of material during high speed deformation. In order to better understand its formation and expansion process, two-dimensional numerical simulation with the Johnson-Cook constitutive model was conducted to reveal shear behaviors of hat-shaped high manganese steel specimens under high-speed impact using the ANSYS/LS-DYNA software. The results show that across the shear band, the strain distributions are the highest in the shear zone center, and are then gradually reduced to the sides, which is similar to a Gaussian distribution, and in the direction parallel to the shear zone, its distributions are characterized by that they are high at both ends and low in the middle. The formation and propagation direction of ASB are determined according to the simulated strain distributions. It is observed that ASBs are formed from both ends of the shear zone and extend to the middle of the samples. Finally, the temperature distributions inside and outside the ASB interior and exterior are obtained directly by editing the k file of the software and they are similar to those of the strain. Simulation and experimental results are shown in good agreement.
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Key words:
- solid mechanics /
- ASB /
- high-speed impact /
- high manganese steels
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图 3 应力时程曲线实验和数值模拟的对比
Figure 3. Comparison of stress-time curves obtained from experimental data and simulation
图 5 等效塑性应变随压下率变化曲线
Figure 5. Relationship between effective plastic strain and reduction rates
图 7 剪切应力与等效塑性应变关系
Figure 7. Relationship between shear stress and effective plastic strain
图 8 不同形变量下剪切区的扫描电镜图
Figure 8. SEM figures of shear zones under different amounts of deformation
图 9 剪切应变分布与冲击时间的关系
Figure 9. Relationship between shear strain distribution and impact time across the shear zone
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