Tayebeh Akbari - University of Applied Science and Technology, Kermanshah, Iran
Gholamhossein Liaghat - Department of Mechanical Engineering, Tarbiat Modares University, Tehran, Iran
Saeid Feli - Department of Mechanical Engineering, Razi University of Kermanshah, Kermanshah, Iran

In this research, the phenomenological model of tumbling perforation presented by Li and Goldsmith has been modified by considering the effect of the frictional force on perforation process of tumbling projectiles. The perforation of blunt–faced cylindrical projectiles in moderately thick aluminum plates – depend on the impact angle in normal or oblique impact – consists of four stages: erosion, plugging, hole enlargement andpetaling. The modeling in the plugging stage consists sequentially of cratering, plug formation, plug separation, plug slipping and post perforationdeformation. The plastic stress waves propagation theory is used to analyze the tumbling perforation. The new analytical results were found to be in good agreement with experimental results

perforation, tumbling, plugging, projectile, oblique impact