Zurich Institute of Forensic Medicine, Department of Forensic Medicine and Imaging, University of Zurich, Winterthurerstrasse 190/52, CH-8057, Zurich, Switzerland.
Institute of Forensic Medicine, Julius-Maximilians-University, Versbacher Str. 3, 97078, Wuerzburg, Germany.
Int J Legal Med. 2020 May;134(3):1133-1140. doi: 10.1007/s00414-020-02270-8. Epub 2020 Mar 11.
Sharp force trauma is routinely encountered in forensic practice. Often the question is posed, how much pressure or energy would have been necessary to inflict a cut with a specific knife, in order to further characterize the perpetrator or determine his intent to cause harm. This paper investigates two knife blades and its individual pressures needed to cut through the epidermis and dermis. In order to examine the necessary force for cutting through the skin, we performed experiments on a piglet skin-on-gelatin phantom. Two similarly small knives-a paring knife with a serrated blade and a Swiss Army pocket knife with a smooth blade-were moved over the phantom surface using a mobile cutting apparatus with varying weight on the load arm with the knife. The depth of the cut was to be determined according to a scale from zero to three: grade 0 = no cut; grade 1 = cut into epidermis only; grade 2 = cut into dermis; grade 3 = complete transection of the entire skin. Each cut inflicted at a specific pressure force was assessed closely in order to ascertain depth, calculate the velocity, and ultimately determine the point at which a cut would inflict grade 3 damage. The smooth blade of a pocket knife needed at least 1900g pressure in order to slice through pig skin mounted on a thick gelatin block, whereas a serrated blade of a paring knife managed to cut into or through the dermis at a comparatively lower force of 700g. Our study shows that at the same cutting velocity, a significant difference in pressure is necessary to inflict the same degree of damage.
锐器伤在法医学实践中经常遇到。通常会提出这样的问题，要施加多大的压力或能量才能用特定的刀造成切割，以进一步描述犯罪者或确定他造成伤害的意图。本文研究了两把刀及其各自的压力，以切割表皮和真皮。为了检查切割皮肤所需的必要力，我们在猪皮-明胶仿体上进行了实验。两把类似的小刀——一把带锯齿刃的削皮刀和一把带光滑刃的瑞士军刀——用带有刀的移动切割装置在仿体表面移动，移动时在负载臂上施加不同重量的力。切割的深度根据从 0 到 3 的刻度来确定：0 级=无切割；1 级=仅切入表皮；2 级=切入真皮；3 级=完全切断整个皮肤。为了确定深度，我们仔细评估了在特定压力下施加的每一次切割，计算速度，并最终确定施加 3 级损伤的临界点。要想在一块厚明胶块上切割安装的猪皮，瑞士军刀的光滑刀刃需要至少 1900g 的压力，而削皮刀的锯齿刃则只需 700g 的相对较小的力就能切入或穿过真皮。我们的研究表明，在相同的切割速度下，要造成相同程度的损伤，所需的压力有显著差异。
