Dynamic delamination in laminated fiber reinforced composites: A continuum damage mechanics approach

Delamination causes a significant reduction in the load carrying capacity of fiber reinforced polymer (FRP) composites, which is a major concern to the aerospace and automotive industries. High performance FRPs are often subjected to dynamic loadings of different energy densities in their service life when strain rate, stress triaxiality, temperature, and mode of fracture can have a significant knock-down effect on the interfacial strength of plies in a laminate. This paper develops a predictive tool, in a continuum damage mechanics (CDM) framework, to assess delamination damage in FRPs under dynamic loading; the model takes into account the effects of dynamic energy density, mixed-mode fractures and temperature. The CDM model is formulated based on the fracture mechanics (FM) of decohesion and an advantage of the proposed model is that nearly all of the material parameters can be obtained directly through calibration to experimental data rather than numerical curve fitting of simulation results. The developed scheme is coded into a commercial FEA package (ABAQUS) through user-defined subroutines and the fidelity of the model is assessed by comparison with existing experimental data in the literature. The validated model is used to investigate delamination damage in a laminated FRP subject to projectile impact loading, where it will be shown that the extent of delamination damage through the thickness of the FRP structure is dependent upon different wave propagation scenarios. The proposed model provides a design platform for damage assessment caused by dynamic delamination and may be a useful tool for designing FRP composites with a greater impact tolerance.

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