Crack and Damage Velocities in Ballistic Experiments

Abstract

A series of ballistic impact experiments were conducted against a borosilicate glass (Borofloat®33) bonded to a polycarbonate substrate. Two of the objectives of the experiments were to measure crack velocities in the glass, and to measure the damage velocity in the glass. The speed of distinct propagating cracks was found to be 1.92 ± 0.03 km/s, independent of impact velocity. The maximum rate of damage propagation was found to be a function of impact velocity, but the damage velocity plateaued at 2.07 ± 0.04 km/s.

On terminal crack velocities in glasses

“…Figure shows the correlation between v ct and v L . All 42 of the glasses that Schardin and Kerkhof tested are shown, as well as Smekal's 1950 data for fused silica and BK‐7 and Anderson et al 2014 data for Borofloat 33 low‐density borosilicate. Kerkhof's ultrasonic v ct data is shown as either green or blue hollow circles.…”

“…Terminal crack velocities are of importance in some applications such as ballistic impact testing . The 1st and 2nd editions of my Guide to Fractography of Ceramics and Glasses cover the topic to some degree, but the next edition will expand on the topic.…”

“…Some borosilicates are notable since they have fast v ct values as shown in Table . Kerkhof measured v ct for Schott Duran glass and Corning Pyrex 7740 and Anderson et al measured it for Schott Borofloat 33. Duran, Pyrex, and Borofloat 33 are very similar in composition, have identical low densities (2.22 g/cm 3 ), nearly identical elastic properties, and have unusually fast terminal velocities: 1920‐1952 m/s.…”

Crack and Shock Propagation Through the Interlayer in Soda Lime Glass Under Detonation Loading

“…The calculated Rayleigh wave speed ( C R ) of the soda lime glass according to Eq. is 3.11 km/s, where v is the Poisson's ratio and C S and C L are the shear and longitudinal wave speeds.…”

“…Therefore, the crack velocity in the forward direction at the initial state is similar to the failure velocity and limit crack velocity as investigated by others. Anderson and coworkers studied the crack and damage velocities of a borosilicate in ballistic experiments. They measured the crack velocity for Borofloat 33 (ν = 0.20) as 1.92 km/s and evaluated it with the Rayleigh wave relation, Eq.…”