The Critical Angle for Perforation versus Ricochet of a .38 CAL. LRN Bullet on a Windshield.

Abstract

From forensic point of view, it is important to clarify the condition whether ricochet or perforate for a bullet fired toward the automobile windshield. The purpose of this study was to specify the critical angle at which the ricochet of the fired bullet takes place. To estimate the result of firing, a rigid-body dynamics simulation of the bullet together with the test-firing using .38 CAL. LRN bullet was examined. It was found both from numerical simulation and firing test that when the incidence angle is <45°, a complete perforation of the windshield was observed, whereas the bullet ricocheted remaining a characteristic damage on the windshield when the incidence angle is >60°. To measure the static failure resistance of various windshields, static indentation test was also examined.