Investigation of High Velocity Impact Responses of a Glass/Epoxy Composite with a Gas Gun

The single stage gas gun testing methodology was investigated. To provide data for computational model development, quantitative measurements of force and displacement were attempted. The transmitted impact force was measured with four load cells installed behind the target. The out-of-plane deformation was measured with a projection grating profilometry method using a high speed camera. The velocity of the projectile was determined using images from the high speed footage. The force and deflection measurements were successful for tests conducted below the ballistic limit. The improved gas gun experiment was used to investigate the high velocity impact behavior of a S2-glass/SC15 epoxy composite. The ballistic limit was found to be 329 and 381 m/s for the 3.8mm (6-ply) and 6.2mm (10-ply) composite panels, respectively. The failure modes of the composite panels were inspected with backlight. The area of damage and failure was found first to increase and then become localized with increasing velocity. As a result, the panels absorbed the same or even a slightly higher amount of energy beyond the ballistic limit, until damage localization. Finally, a new method to compare the ballistic protection capability of different materials is presented.