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一、“钳剪痕迹”概念质疑目前,多数工具痕迹学教材和论文在分析钢丝钳和剪刀破坏客体形成的痕迹时使用“钳剪痕迹”这一概念,指罪犯利用钳剪刃口施行剪切作用破坏客体时在接触部位出现的变形,其外延包括钢丝钳的钳切痕迹和剪刀的剪切痕迹;分析受力时对钳切与剪切过程均应用材料力学中剪切变形的理论和实用计算方法,认为刃口给承痕客体施加的力是大小相等、方向相反、作用线平行且相距很近的两个力,在此二力作用下承痕客体产生剪切痕迹,并应用了剪应力的计算公式:
First, the concept of “pliers scissors” questioned At present, most of the tools, traces of textbooks and papers in the analysis of the wire pliers and scissors to destroy the formation of traces of the use of "pliers scissors traces the concept of criminals use the cutting edge shear The role of deformation in the contact area when the object is damaged, the extension of which includes the cutting pliers wire cutting marks and scissors cutting traces; analysis of force applied to the pincer-cut and shear process are both shear mechanics in the theory and practical The calculation method shows that the forces exerted on the object by the cutting edge are two forces of the same size, opposite directions and parallel and close action lines. Under the action of these two forces, there are shear marks on the bearing object, Stress calculation formula: