| 不同加载状态下TA2钛合金绝热剪切破坏响应特性 |
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| 引用本文： | 周刚毅,董新龙,付应乾,虎宏智. 不同加载状态下TA2钛合金绝热剪切破坏响应特性[J]. 力学学报, 2016, 48(6): 1353-1361. DOI: 10.6052/0459-1879-16-198 |
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| 作者姓名： | 周刚毅 董新龙 付应乾 虎宏智 |
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| 作者单位： | 1. 宁波大学机械工程与力学学院, 宁波 315211;2. 北京理工大学机电学院, 北京 100190 |
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| 基金项目： | 国家自然科学基金(11172144)，NSAF联合基金(U1230122) |
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| 摘 要： | 一般认为绝热剪切现象在宏观上表现为材料动态本构失稳,即热软化大于应变硬化.本文采用帽型受迫剪切试样研究TA2钛合金的动态力学特性和本构失稳过程.首先对剪切区加载应力状态进行理论和数值分析,通过合理设计帽型试样,剪切区变形可近似按剪切状态处理;结合二维数字图像相关法(two-dimensional digital image correlation,DIC-2D)直接测试试样剪切区应变演化,给出帽型受迫剪切实验的等效应力-应变响应曲线.进一步,利用Hopkinson压杆对TA2钛合金开展动态压缩及帽型剪切对比试验研究,比较压缩、剪切试验得到的等效应力-应变曲线,采用"冻结"试样方法分析试样中绝热剪切局域化演化过程,探讨不同加载状态下TA2钛合金的绝热剪切破坏现象及其动态力学响应特性.实验结果表明,在塑性变形初始阶段,动态压缩及剪切加载下的等效应力-应变曲线符合较好,但随塑性损伤发展及绝热剪切带形成,两者出现分离,表明损伤及绝热剪切演化过程与应力状态相关.剪切试样实验得到的本构"软化"特性能够反映绝热剪切带起始、破坏演化过程的力学响应特性,而在动态压缩实验中,即使试样中已出现双锥形的绝热剪切带及局部裂纹分布,其表观等效应力-应变曲线并不出现软化特征,动态压缩实验无法得到关于绝热剪切起始、发展以及破坏的本构软化响应特性.
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| 关 键 词： | 加载状态 TA2钛合金 帽型试样 绝热剪切 动态特性 |
| 收稿时间： | 2016-07-15 |
| 修稿时间： | 2016-09-12 |
AN EXPERIMENTAL STUDY ON ADIABATIC SHEAR BEHAVIOR OF TA2 TITANIUM ALLOY SUBJECT TO DIFFERENT LOADING CONDITION 1) |
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| Zhou Gangyi,Dong Xinlong,Fu Yingqian,Hu Hongzhi. AN EXPERIMENTAL STUDY ON ADIABATIC SHEAR BEHAVIOR OF TA2 TITANIUM ALLOY SUBJECT TO DIFFERENT LOADING CONDITION 1)[J]. chinese journal of theoretical and applied mechanics, 2016, 48(6): 1353-1361. DOI: 10.6052/0459-1879-16-198 |
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| Authors: | Zhou Gangyi Dong Xinlong Fu Yingqian Hu Hongzhi |
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| Affiliation: | 1. Faculty of Mechanical Engineering and Mechanics, Ningbo University, Ningbo 315211, China;2. Shool of Mechatronical Engineering, Beijing Institute of Technology, Beijing 100190, China |
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| Abstract: | Adiabatic shear phenomena is generally considered as a material dynamic instability,which comes from the competition among thermal softening and the strain hardening, strain rate hardening. In this paper, the constitutive and dynamic behaviors of TA2 titanium alloy were studied with hat-shaped forced-shear specimens.. The stress states of its shear zone are firstly studied by theoretical analysis and numerical simulation to obtain the pure state of shear stress with the hat-shaped samples. The shear strain in specimen measured directly by the two-dimensional digital image correlation (DIC-2D) method, and the equivalent stress-equivalent strain curves under forced shear loading can be acquired. Fur-thermore, the dynamic stress-strain behaviors in compression conditions and hat-shaped shear condition are then studied experimentally for TA2 titanium alloy by split Hopkinson pressure bars technique. Its adiabatic shear failure evolution is investigated by microscopic metallurgical observation of ’freezing’ sample. The dynamic constitutive and failure behavior of TA2 titanium alloy subject to different loading condition are analyzed. The results show that the dynamic constitutive curves obtained by cylindrical compression are in agreement with the curves of shear testing at the initial stage of plastic deformation, but its stress-strain curve appears separation with the plastic damage accumulation and adiabatic shear band (ASB) formation, which suggests that the plastic damage and ASB origination may be with the relevant the state of stress. It is also shown that the softened stress-strain curve gained by shear loading reflected ASBs initiation and evolution in the hat-shaped specimens, by contrast, the apparent equivalent stress-strain curve obtained by compression testing does not appear to be softening characteristic even if the symmetrical bi-conical ASBs and local crack distribution have appeared in the cylindrical specimen. |
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| Keywords: | loading condition TA2 titanium alloy hat-shaped specimens adiabatic shear band dynamic characteristics |
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