Various impact characteristics as well as fracture energy can be estimated by using an instrumented impact testing technique. The impact characteristics, such as a load versus deflection curve and maximum load, are used only for comparison among materials, but are seldom used for strength assessment in structural design. The analytical procedure which correlates the simple test data with structural strength under complex boundary conditions has not been established. In the present paper, a numerical method for dynamic strength analysis has been proposed and applied to estimate the multiaxial impact strength of aramid/glass hybrid composite plates.
Dynamic fracture simulation based on the maximum stress criterion was carried out by using a finite element method and the numerical results were compared with the experimental data obtained by an instrumented drop-weight impact testing machine. Seven kinds of hybrid laminates were used for the tests, including roving-cloth reinforced composites, glass mat reinforced composite and mat/roving-cloth reinforced composites. The progressive fracture process under impact loading was well simulated and the numerical results showed close agreement with the experimental data which exhibit brittle fracture. The fracture controlling process of mat/roving-cloth reinforced laminates was also discussed quantitatively based on the present analysis.