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71.
This paper provides an investigation of the phase
transition and spalling characteristic induced during shock loading
and unloading in the pure iron and the FeMnNi alloy. The impact for
the pure iron is symmetric and with same-thickness for both the
flyer and the target plate. It is found that an abnormal multiple
spalling happens in the pure iron sample as the pressure exceeds the
$\alpha -\varepsilon $ transition threshold of 13 GPa. In the
symmetric and same-thickness impact and reverse impact experiments
of the FeMnNi alloy, two abnormal tension regions occur when the
pressure exceeds the $\alpha -\varepsilon $ transition threshold of
6.3~GPa, and the reverse phase transition $\varepsilon -\alpha $
begins below 4.2~GP. The experimental process is simulated
successfully from the non-equilibrium mixture phase and Boettger's
model. Such abnormal spalling phenomena are believed to relate to
the shocked $\alpha -\varepsilon $ phase transition. The possible
reasons for the abnormal multiple spalling, which occurs during the
symmetric and same-thickness impact experiments of pure iron and
FeMnNi alloy, are discussed. 相似文献
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针对爆轰波对碰驱动下金属圆管对碰区易出现过早断裂的问题,以加环紫铜(T2)圆管作为研究对象,利用高速分幅摄影、脉冲X光照相、VISAR三种测试技术,对其在爆轰波对碰驱动下的变形及破坏过程进行了观测。实验结果显示:在紫铜圆管对碰部位增加保护环结构,可以有效推迟该部位圆管的破裂时间。但同时也发现:加保护环后圆管对碰区会出现射流状超前突起现象。由高速摄影结果与X光照相结果对比分析证实:射流状超前突起物质为圆管表面微喷颗粒与空气冲击波混合形成的雾状结构。另外,采用DYNA3D程序对实验模型进行了模拟,计算结果与实验结果符合较好。最后,利用DYNA3D程序就保护环倒角变化对金属圆管对碰区壳体破裂的影响特征进行了初步分析。 相似文献
75.
爆轰加载下金属柱壳膨胀破裂过程研究 总被引:15,自引:7,他引:8
采用前照明的高速分幅照相对不同壁厚的45钢柱壳在爆轰加载下的膨胀破裂过程进行了研究,实验成功拍摄到45钢柱壳前表面裂纹生成、扩展及产物泄漏的过程图像。研究表明:膨胀应变率在104s-1附近时,随着应变率的增加,45钢柱壳的各特征应变均有所增加,断裂模式由拉剪混合向单一剪切转变;45钢柱壳的膨胀破裂有一个过程,从柱壳的外壁面可以观察到裂纹生成至产物开始泄漏经历时间历程的长短与柱壳壁厚相关,柱壳壁越厚,从外壁出现裂纹到产物开始泄漏的时间间隔越长;由回收破片厚度测量推算出的膨胀断裂应变与动态实验过程中产物开始泄漏时的断裂应变基本一致。 相似文献
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