倾斜角度射击与玻璃破碎痕迹分析

Relationship between Oblique Hitting and Glass Broken Patterns

本文通过在实验室环境下模拟低速状态下弹丸倾斜角度撞击玻璃情景,制作了5个射击角度下的玻璃破碎痕迹样本,对不同射击角度下的玻璃破碎痕迹二维平面的形态及三维立体结构进行分析。笔者为玻璃破碎痕迹的不同区域做出定义,分别为弹着点痕迹、圆台形张应力作用区痕迹和张应力衰减区痕迹,研究发现在二维平面下随射击角度改变玻璃破碎痕迹有弹着点呈椭圆状、痕迹下沿光滑上沿陡峭、圆台形张应力区痕迹与弹着点上沿距离较小等形态特征,在三维立体结构中在倾斜角度射击环境下玻璃破碎痕迹内部各结构间存在倾斜关系且倾斜度与角度相关。最终笔者通过分析低速弹丸的射击角度与玻璃破碎痕迹形态之间的关系并探究其形成原因,达到通过分析玻璃破碎痕迹形态判断出弹丸射击角度的目的,为案件侦破提供技术保障。

One simulative experiment was carried out that glass was obliquely hit with low-speed pills in laboratory, bringing out the glass samples cracked with 5 projecting angles. The broken patterns of the hit glass were analyzed under two and three dimensions to unfold their planar and cubic structures. Three cracked patterns are de？ned： the one at hitting point, the one of stress-spreading and resembling a truncated cone, and the one of stress decaying. The pattern at the hitting point observed under two dimensions was found of oval-shape and changing along with the shooting angles, showing a smooth downside edge and the steep upside one. The pattern of stress-spreading and resembling a truncated cone is closer to the upside edge of the hitting point. Observed under three dimensions, the inside structures of the broken patterns resulted from oblique hitting onto the glass are related to hitting angles. Presumably, based on the relationship between broken patterns and hitting angles that glass was obliquely struck with low-speed pills, a pill’s shooting angle could be deduced from the broken patterns on the hit glass.