Damage Mechanism of Glass Composite Armor Subjected to Projectile at High Impact Velocity

The glass laminated composite armor exhibits good light transmission and impact resistance, making it widely used in military and civil protection fields. However, due to the susceptibility of glass to failure and breakage, the experiments and numerical simulations were carried out to investigate the impact damage mechanism of the target plate under high-speed impact of the steel ball projectile. Results show that under the action of breaking cone of first glass layer and stress wave propagation, the volume of breaking cone in the second layer of glass and the overall damage area are significantly larger than those in the first layer. During high-speed impact, many radial and circumferential cracks form in the glass layer. The circumferential cracks, resulting from Rayleigh waves, can prevent the propagation of secondary cracks caused by the radial crack propagation. The glass layer can be divided into the powder region, small fragment region, large fragment region and radial crack region according to different damage degrees. Along the thickness direction, the combined action of stress wave propagation, bending deformation of the target plate and volume expansion of the broken glass result in vertical and oblique cracks along the breaking cone in the glass layer. The PU bonding layer between the glass layer can deflect vertical cracks and hinder the propagation of the cracks along the thickness direction. At the interfaces between the glass/PU/PC layers, shear wave action arises due to the differences in dielectric wave impedance, leading to localized stratification within the adhesive layer. The deformation of PC layer gathers broken glass particles, forming a local high-stress area and complets the continuous obstruction of the projectile. Finally, the deformation of the PU adhesive layer is primarily induced by the shear stress caused from the breaking cone of the glass layer.