Two-scale modeling of high-velocity fragment GFRP penetration for assessment of ballistic limit

The present paper deals with the ballistic testing and numerical modeling problems of fragment penetration of glass fabric/epoxy-phenolic (GFRP) laminates. Two laminates of different thickness (1.95 and 3.90 mm) were subjected to ballistic impact of 6.35 mm dia steel sphere as a fragment simulator at different velocities to get ballistic curves. There were developed the continuum-based model (CBM) and the microstructural model (MSM) of GFRP laminates in two finite element codes (AUTODYN-3D and LS-DYNA). The CBM is a model of anisotropic body with the fiber-dominated failure mechanics. The advantages of this model include short CPU time and good prediction of ballistic limit velocity with the use of only two free parameters of failure model to be determined from preliminary dynamic experiments. The MSM has geometrically accurate GFRP structure and assumption of isotropy and simple failure criteria of constituents (fiber bundles and matrix) not only to get the ballistic limits, but also to describe in details the damage mechanisms of GFRP laminates. The numerical simulation results showed a good correlation with the experimental data in terms of ballistic curves and internal material damage.