IMPACT ON ALUMINUM PLATES BY TUMBLING PROJECTILES - EXPERIMENTAL-STUDY

An experimental investigation into the effects due to tumbling of 12.7 mm diameter, hard-steel, blunt-faced cylindrical projectiles with an L/D ratio of 3 on the impact response of thin and moderately thick alu minum targets was performed. Projectiles were fired from a powder gun and tumbling motion was induced by a special generator. A high speed c amera was employed to obtain data for the impact phenomena. Deformatio n patterns, failure phenomena and crater lengths of the targets as wel l as the final velocities and trajectories of the projectiles were cor related with initial kinematic information, such as the initial transl ational velocity, impact angle (or yaw angle with a zero oblique angle ), oblique angle of the projectiles, and plate thickness which ranged from 4.8 to 12.7 mm. The range of velocities and impact angles was 300 -600 m/s and 0-50 degrees, respectively. It was found that the impact angle plays a major role in the penetration process. The impact angle can reduce the penetration capability and change the trajectory of the projectile substantially. Impact at an angle above 50 degrees has alm ost the same effect as side-on impact at an impact angle of 90 degrees for the ranges of velocity and target thickness presently investigate d. Predictions from an analytical and a numerical model are presented in a companion paper.