WOVEN GLASS EPOXY LAMINATES SUBJECT TO PROJECTILE IMPACT

Impact results of woven E-glass/epoxy composite laminates are presente d in this paper. A gas gun was employed to launch 12.7 mm diameter hem ispherically-tipped projectiles 35.5 g in weight. The developed laser Doppler anemometer (LDA) system was successfully employed to record th e projectile velocity history, whose range was from several m/s to twi ce the ballistic limit of the target, and was converted into the force history by using both the optimization and the polynomial curve-fitti ng methods. It was found that, when the projectile initial velocity wa s lower than the ballistic limit, the delamination area was approximat ely proportional to the initial energy of the projectile, and the rela tionship between the absorbed energy and initial energy of the project ile followed a straight line of unit slope when it was expressed non-d imensionally. Also, the incremental rate of the peak impact force beca me gradually smaller and finally reached a constant value at the balli stic limit, and the impact force history became progessively asymmetri c. Beyond the ballistic limit, the absorbed energy remained approximat ely constant regardless of the increase of the initial striking veloci ty of the projectile. The peak impact force, on the other hand, was su rprisingly found to increase again.