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首页> 外文学位 >Penetration and induced damage evolution of concrete and granite when subjected to multiple projectile impacts.
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Penetration and induced damage evolution of concrete and granite when subjected to multiple projectile impacts.

机译：遭受多次弹丸冲击时，混凝土和花岗岩的渗透和诱发的损伤演化。

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摘要

An experimental study was conducted to investigate the penetration process of multiple impacts into concrete targets. The concrete targets were subjected to repeated constant velocity impacts with an ogive nose projectile. The penetration and crater formation data were consistent with single impact penetration data from previous studies conducted at Sandia National Laboratories.; In order to predict the depth of the multiple impact penetration, a single impact penetration model, developed by M. Forrestal at Sandia National Laboratories, was extended to account for the degradation of the target strength with each subsequent impact. The degradation of the target was determined empirically and included in the model as a strength-modifying factor.; To further understand the multiple impact penetration process, a study was conducted to look at both the static and dynamic properties of concrete and granite as a function of induced damage.; Both static and dynamic compression experiments were performed on concrete and granite specimens with various levels of induced damage. The static compressive strength of both materials decreased with increasing levels of damage due to the induced damage causing the activation and propagation of failure cracks in the specimens. In contrast, the dynamic compressive strength remained unchanged with increasing damage due to the inability of the fracture process zone to develop and relieve the strain energy before complete specimen failure.; A series of dynamic and static tensile-splitting experiments were performed on concrete and granite specimens to investigate the effect of induced damage on their tensile strength. The experiments showed that the static splitting strength was highly dependent on the orientation of the induced damage with regard to the applied loading, however the dynamic tensile strength decreased with increasing damage with no apparent dependency on the random damage orientation. Photoelastic experiments have shown that the mechanism of failure changes for the dynamically tested damaged specimens, reducing their dependence on damage orientation. The photoelastic experiments also determined that the tensile splitting specimen was in equilibrium at the time of failure, and that the dynamic stress field closely resembles the static splitting stress field.
机译：进行了一项实验研究，以研究多种冲击力对具体目标的渗透过程。具体的目标经受了带有钝头射弹的反复恒速冲击。熔深和弹坑形成数据与之前在桑迪亚国家实验室进行的研究得出的单冲击熔深数据一致。为了预测多重冲击穿透的深度，扩展了由Sandia国家实验室的M. Forrestal开发的单个冲击穿透模型，以解决每次后续冲击时目标强度的下降。凭经验确定目标的退化，并将其作为强度修改因子包含在模型中。为了进一步理解多重冲击渗透过程，进行了一项研究，以研究混凝土和花岗岩的静态和动态特性与诱发损伤的关系。在混凝土和花岗岩试样上进行了静态和动态压缩实验，这些试样具有不同程度的诱发损伤。两种材料的静态抗压强度都随着损伤程度的增加而降低，这是由于诱发的损伤导致试样中裂纹的活化和扩散所致。相反，由于断裂过程区无法在完全破坏试样之前形成并释放应变能，因此动态抗压强度随着破坏的增加而保持不变。在混凝土和花岗岩样品上进行了一系列的动态和静态拉伸分裂实验，以研究诱导损伤对其拉伸强度的影响。实验表明，静态劈裂强度在很大程度上取决于所施加载荷的诱导损伤方向，但是动态拉伸强度随损伤的增加而降低，而对随机损伤取向没有明显的依赖性。光弹性实验表明，动态测试的受损试样的破坏机理发生了变化，从而降低了其对损伤取向的依赖性。光弹性实验还确定了断裂时拉伸分裂试样处于平衡状态，并且动态应力场与静态分裂应力场非常相似。

著录项

  • 作者

    Gomez, Jason Thomas.;

  • 作者单位

    University of Rhode Island.;

  • 授予单位 University of Rhode Island.;
  • 学科 Engineering Mechanical.; Engineering Materials Science.
  • 学位 Ph.D.
  • 年度 2000
  • 页码 133 p.
  • 总页数 133
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 机械、仪表工业;工程材料学;
  • 关键词

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