Applied Ergonomics 36 (2005) 505–511 The effect of knife handle shape on stabbing performance Ian Horsfall à , Celia Watson, Steve Champion, Philip Prosser, Trevor Ringrose Royal Military College of Science, Cranfield University, Shrivenham, Swindon, Wiltshire SN6 8LA, UK Received 24 January 2003; accepted 13 December 2004 Abstract Aquantitativeknowledgeofstabbingabilityisapre-requisitetoestablishingprotectionstandardsforstabresistantbodyarmour. In order to determine the validity of measurements it is necessary to understand all the mechanisms that determine performance. Thispaperdescribesaseriesofteststhatwereperformedinordertodeterminetheeffectofhandlesizeandshapeontheforcesand impactenergythatcouldbeproducedduringstabbingofanarmouredtarget.Itwasfoundthatthesinglelargestvariablewasthat ofthetestparticipantswithallothervariablessuchashandlesizeandshapehavingonlyslighteffectsonthemagnitudeofimpact energy. The use of a finger guard or hilt was shown to increase the mean energy delivered to the target by approximately 5J comparedtoahandlehavingnoguard.Itwasalsofoundthatthecharacteristicsofenergydeliverywerestronglyinfluencedbythe position of the grip relative to this guard. This reinforces the conclusions of previous work (Horsfall et al., 1999; Chadwick et al., 1999) on the serial nature of momentum transfer during a stabbing impact. r 2005 Elsevier Ltd. All rights reserved. Keywords: Body armour; Stabbing; Handle geometry 1. Introduction Stab resistant body armour is now a standard item of equipmentforpoliceofficersintheUnitedKingdom.The armour is usually required to have a stab resistance as specified by the Police Scientific Development Branch standard (Croft, 2003). This and all other test standards (H.P. White Laboratory, 1988; Schweizerische Polizei- technische Kommission, 1992; Department for Police Technology, Munster, 1994; ISO/DIS 14876-3, 1999; NIJ, 2000), require that body armour must resist penetration by a specific blade type, delivered at a specific energy level or range of levels. However, the actualrangeofenergylevelsstipulatedinthesestandards varies over more than an order of magnitude and the basis for these levels is not always clearly defined. A number of studies have investigated the character- istics of stabbing attack for the establishment of test standardsforpolicebodyarmour(Horsfalletal.,1999; Chadwicketal.,1999),forensicstudiesofknifewounds (Knight, 1975; Miller and Jones, 1996; Green, 1978; Jones et al., 1994), and archaeological aspects of edged weapons performance (Connolly et al., 2001). Typically these studies have investigated the forces, energies and velocitiesthatcanbegeneratedinastabbingattackand to some extent the resistive loads during penetration. In a previous study (Horsfall et al., 1999), a large numberofvolunteers(4500)usedaninstrumentedknife to stab standardized targets during which their perfor- mance was monitored. From the data it was possible to determine the range of performance of a sample group includingarangeofagesandabilities.Oneareathatwas notexaminedwastheeffectoftheknifegeometryandin particular the geometry of the hilt. It might be assumed that a large well-shaped handle as used in previous assessments would allow a better grip on the knife than the small handles which characterise the majority of foldingknives.Asfoldingknivesandsmallkitchenknives are used in a large number of stabbing incidents it was decidedtotesttheeffectofhandlegeometryonstabbing ARTICLE IN PRESS www.elsevier.com/locate/apergo 0003-6870/$-see front matter r 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.apergo.2004.12.001 à Corresponding author. Tel.: +441793785389; fax:+441793783192. E-mail address: i.horsfall@cranfield.ac.uk (I. Horsfall).