Abstract: In order to analyze the ballistic characteristics of composite structures, a rate-dependent constitutive model is developed to simulate the response of the uni-directional fiber reinforced composite under high velocity impact based on the assumption that the fiber is linear-elastic and the matrix is visco-elastic. The first-order shear deformation laminate theory is deduced at high strain rate. A finite element model is established to simulate the ballistic response of the stiffened composite panel. In this model, the cohesive elements are used to simulate the delamination of the composite panel and debonding between the composite panel and the stiffener. The Hashin's failure criteria are used to predict the inplane failure of the stiffener and composite panel by replacing quasi-static strength properties with rate-dependent strength properties. By using a degradation constitutive model of the mechanical properties, the damage of a stiffened composite panel under high velocity is simulated. The numerical results agree well with the experimental results. Parametric studies are conducted to study the effect of the stiffener parameters on the damage of the stiffened composite panel. A number of valuable conclusions are obtained.

Key words: composite materials, constitutive models, stiffened panel, impact, damage, numerical analysis