Fracture Phenomena In Soda Lime Silica Glass Caused By Bullet Impacts
Loading...
Date
2012-02
Authors
Syed Mohd Daud, Sharifah Mastura
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
A series of studies was performed under controlled experimental conditions to investigate the fracture patterns produced in static loading (ball dropping experiments) and also the impacts of bullets of different calibres and nose shapes, fired from different weapons, onto soda lime silica glass of different dimensions and thicknesses. The results obtained in static loading experiments confirmed the earlier findings reported in the literature. In the bullet induced glass fracture experiments, all the bullets were fully metal jacketed except .38 in. Special ones that had exposed lead. Nose types varied from round nose and flat nose to hollow point. The velocity of the bullets varied from 220 to 1020 m/s. Two chronographs, one placed in front of the glass target and the other immediately behind it, measured the striking and remaining velocities of the bullets. The bullets after penetration of the glass were recovered using a bullet catch. The resulting crack patterns on glass were studied for their characteristics and surface markings. Some of them were also analysed quantitatively using the concept of fractal dimension that measured the complexity of irregular patterns. Observations revealed substantial differences in the behaviour of the bullets to produce fracture patterns in the glass. These patterns were much different from those produced during static loading tests. Each bullet of a specific calibre and type produced a unique pattern by which it can be identified. Further, the same calibre bullets (9 mm round nose and flat nose, and 5.56 mm rifle calibre) discharged from two different weapons (pistol and sub machine gun for 9 mm calibre/ and rifle and Carbine for 5.56 mm calibre) produced distinguishable patterns according to each weapon. The bullets deformed by mushrooming and shearing of its tip confirming the ductile nature of the projectiles at high velocities. The percentage of bullet deformation showed linear relationship to the complexity of the resulting fracture pattern: the greater the percentage the more complicated the patterns that were formed. The velocity loss for a specific calibre for a given thickness of glass was almost same irrespective of the striking velocity.
Description
Keywords
The fracture patterns produced in static loading , impacts of bullets of different calibres