Showing papers on "Ballistic impact published in 1974"
TL;DR: In this article, the effects of preload, of ply layups, and of projectile velocity have been examined for 30 caliber armor-piercing projectiles striking the plate at a 0 deg obliquity.
Abstract: The tolerance to ballistic impact of graphite/epoxy and boron/epoxy composites has been investigated. The effects of preload, of ply layups, and of projectile velocity have been examined for 30 caliber armor-piercing projectiles striking the plate at a 0 deg obliquity. A limited number of tests were performed on glass/epoxy laminates and on type 6061-T6 aluminum panels. Several tests were conducted using 50 caliber armor-piercing projectiles. High-speed photography was used to determine the overall ballistic response, as an additional check on projectile velocity, and to determine when crack initiation occurred. The fracture toughness of each type of laminate was determined and both the residual strength (the nominal stress to which a panel which did not fail during performation can be loaded) and the threshold strength (the lowest pre-impact stress which results in failure upon impact) are shown to correlate directly with the toughness.
6 citations
TL;DR: Impact performance by the ballistic technique was determined for 720 test ophthalmic lenses including non‐treated, heat‐treated and chemical‐treated glass lenses and plastic lenses, finding that all four types lost impact strength after being scratched on the front surface.
Abstract: ABSTRACT Impact performance by the ballistic technique was determined for 720 test ophthalmic lenses including non‐treated, heat‐treated and chemical‐treated glass lenses and plastic lenses. Half of the lenses were abraded on the front surface. Plastic lenses had the greatest impact resistance, while non‐treated glass lenses had the least. Chemical‐treated and heat‐tempered glass lenses offer similar impact protection. All four types lost impact strength after being scratched on the front surface.
5 citations
01 Jan 1974
TL;DR: In this article, the authors present theoretical models for either the static or the shock failure under subsonic impact for the stock removal process, which can be directly applied to the stock-removal process.
Abstract: Analysis of the ceramic stock removal system is a complex process, basically involving the transfer of energy from the grinding wheel to the ceramic workpiece. This involves the various factors generally accompanying the phenomenon of material failure under ballistic impact. However, the shock front normally encountered in ballistic impact is not generated here, since the impact velocities are subsonic. On one hand, this simplifies the matter by avoiding the complications associated with shock front propagation while on the other hand theoretical schemes to analyze the fracture under subsonic impact are not as fully developed as those for the shock front propagated fracture. Furthermore, the existing theoretical models for either the static or the shock failure cannot be directly applied to the stock removal process for at least the following reasons:
1.
Many major phenomena act simultaneously, such as high velocity impact, crack propagation, wear and friction processes.
2.
Experimental parameters: specific conditions and their variations are often extreme. As an example, interfacial pressures may reach levels of 25 kilobars, within one tenth of a microsecond; temperatures of around 1500° Kelvin are experienced.
3.
The process is a continuous dynamic process; that is, there is a very definite time period over which the material continues to be subjected to impact parameters, after the initial impact is made.
3 citations