Dynamic material properties of orthotropic polymer and molybdenum for use in next generation composite armor concept

Abstract

Dyneema HB-25 is an orthotropic polyethylene fiber-epoxy matrix material that is being investigated for use in a next generation layered armor concept. Dyneema was chosen due to its high variation in sound speeds in the through direction and along the fiber direction, thereby making it a good candidate for a wave spreading layer in our proposed armored layer concept. The shock properties in the through fiber direction have been investigated using traditional window experiments and experiments using buffer materials at projectile velocities varying from 0.250 km/s to 1.800 km/s. The shock Hugoniot relationship was found to be non-linear in the low pressure regime that was investigated here and was found to be: 2 Us 1.673u p 4.847u p 0.902 . The shock properties of polycrystalline Molybdenum were also investigated; specifically the sound speed at shock state stress level. The relationship between sound speed and stress can be useful in predicting phase changes within materials. The low pressure regime of these properties was investigated in order to provide anchor data for previous work completed on Molybdenum.