Measuring Knife Stab Penetration Into Skin Simulant Using a Novel Biaxial Tension Device M.D
Available online at www.sciencedirect.com Forensic Science International 177 (2008) 52–65 www.elsevier.com/locate/forsciint Measuring knife stab penetration into skin simulant using a novel biaxial tension device M.D. Gilchrist a,*, S. Keenan a, M. Curtis b, M. Cassidy b, G. Byrne a, M. Destrade c a Centre for Materials & Manufacturing, School of Electrical, Electronic & Mechanical Engineering, University College Dublin, Belfield, Dublin 4, Ireland b State Pathologist’s Office, Fire Brigade Training Centre, Malahide Road, Marino, Dublin 3, Ireland c Institut Jean le Rond d’Alembert UMR7190, Universite´ Pierre et Marie Curie, Boite 162, 4 Place Jussieu, 75252 Paris, France Received 3 August 2007; received in revised form 28 September 2007; accepted 31 October 2007 Available online 21 February 2008 Abstract This paper describes the development and use of a biaxial measurement device to analyse the mechanics of knife stabbings. In medicolegal situationsitis typicaltodescribe theconsequences ofa stabbingincidentinrelative termsthatare qualitativeanddescriptivewithoutbeing numerically quantitative. Here, the mechanical variables involved in the possible range of knife–tissue penetration events are considered so as to determine the necessary parameters thatwould needto becontrolled in a measurement device. These include knifegeometry,in-planemechanical stressstateof skin, angle and speed of knife penetration, and underlying fascia such as muscle or cartilage. Four commonly available household knives with different geometries were used: the blade tips in all cases were single-edged, double-sided and without serrations. Appropriate synthetic materials were usedto simulate the response of skin, fat and cartilage, namely polyurethane, compliant foam and ballistic soap, respectively. The force and energy appliedby the blade of the knife and the out of plane displacement of the skin were all used successfully to identify the occurrence of skin penetration.
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