An Experimental and Numerical Investigation of Thickness Effect on Cross-Ply GLARE 5 FML Plates Subjected to Ballistic Impact

GLARE 5 fiber-metal laminated (FML) plates of dimensions: 152.4 mm × 101.6 mm with various thicknesses, ranging from 1.12 mm up to 4.37 mm, were impacted by a 0.22 caliber bullet-shaped projectile using a high-speed gas gun. A high-speed camera was used to measure the projectile velocity along its ballistic trajectory. The post-impact damage characteristics were evaluated using both nondestructive ultrasonic and destructive mechanical sectioning techniques. Only the contour of the entire damage area could be obtained using ultrasonic C-scan; whereas more details of the damage were provided through the mechanical cross-sectioning technique. As expected, thicker GLARE 5 offered higher impact resistance. It was found that by increasing the specimen thickness, the damage contour increased. In addition, the results showed that for a given specimen thickness, the damage contour was maximized near its ballistic limit velocity. The 3D dynamic nonlinear finite element (FE) software, LS-DYNA, was used to validate the experimental results. Good agreement between experimental and FE results was obtained.