New Trends in Research of Energetic Materials, Czech Republic, 2011 1026 Characterization of distribution parameters of fragment mass and number for conventional projectiles Berko Zecevic*, Jasmin Terzic*, Alan Catovic*, and Sabina Serdarevic-Kadic* * University of Sarajevo, Mechanical Engineering faculty, Bosnia and Herzegovina zecevic@mef.unsa.ba Abstract: Assessment of parameters of high explosive (HE) projectile fragmentation process (mass distribution and number of fragments) in most of the scientific papers is generally best de- scribed using Mott (depending on dimensionality and different scaling models) and Held equations. These methods can describe mass distribution of fragments excellent, but pre- cise data about individual parameters from these equations are not available in public lit- erature. During the previous eksperimental research of natural fragmentation for several types of HE projectiles, authors are studied the effects of several types of projectile body materials, two types of high explosive and projectile design and determined range of pa- rameters using in Held laws. Obtained data can help designers with smaller experimental experience to make faster prediction of new projectile fragmentation parameters. Keywords: Natural fragmentation; Mass distribution; Held methodology 1 Introduction Natural fragmentation of projectiles or warheads results in the formation of a large number of fragments of different masses and geometries. Expansion of projectile body by detonation products of explosive charge causes a warhead to split into various sized fragments. Fragment mass distribution depends on warhead geometry, diameter and length of ex- plosive charge, thickness of projectile body, body material, its mechanical characteristics and thermal treatment, as well as explosive charge type. Determination of warhead performances requires very complex measuring equipment and measuring process itself is expensive as well. Number, mass and shape of fragments are gener- ally determined in Pit test. Spatial distribution of fragments can be determined using Arena test. In more complex Arena tests, fragments can be caught and their velocity could be deter- mined, while in simpler Arena tests, only fragment spatial density is measured. The authors used the results of a large number of tests, and applied statistical and numeri- cal methods. Capability to make warhead performance prediction in the earliest phases of ammunition or warheads preliminary design is crucial. Ability for warhead performances prediction de- pends on comprehensive data base of warheads natural fragmentation features, including data on fragment mass, number and shape, initial fragment velocities, warhead case and explosive material performances and spatial fragment distributions. Using experimental test of natural fragmentation for several types of high explosive projec- tiles and available numerical and statistical techniques, authors tried to show basic natural fragmentation peremeters for four types of projectile. Data on aerodynamics and dynamics of flight for fragments are presented. Cha1026racterization of Held’s constants was performed, and prediction of initial fragment velocities, and lethal zones for four types of projectile was made.