We analyze by the finite element method transient deformations of a helmet mounted on a Roma Plastilina #1 clay-filled rigid and stationary headform. The helmet is made of a unidirectional fiber reinforced composite that is modeled as a linear elastic orthotropic material. Hashin's criteria are used to simulate the fiber and the matrix failure. The clay (impactor) is modeled as an elastic-plastic (elastic-viscoplastic), isotropic and homogeneous material. The problem is numerically solved by using the commercial software, ABAQUS, with built-in algorithms to simulate contact between distinct materials (e.g., the clay, the helmet, and the penetrator), and to delete elements whose material has failed. We have verified capabilities of the software for analyzing the penetration problems by solving a few impact problems that have been previously studied by others either experimentally or numerically. The effect of the number of layers in the helmet and the crater formed in the clay due to the impact of the projectile on the helmet has been delineated. It is believed that the crater size in the clay will provide useful information regarding the head injury trauma caused by the impact of a projectile on the helmet. / Master of Science