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Techniques for Relating Stresses and Strains in Fabrics and Fiber-Reinforced Composites between Various Hierarchical Scales



Fiber-reinforced composites and fabrics in armor systems and other structures subjected to high-rate impacts resist perforation through multiple deformation and failure mechanisms, which individually affect the constitutive stress-strain behavior of these materials. The complex behavior of these materials requires either a complex mesh geometry, as is characteristic of mesoscale models, or a complex material model, as is characteristic of continuum models. However, many purported continuum material models for composites in the literature require separate elements for different unidirectional lamina and only consider the effects of stresses and strains on the material behavior at the lamina scale, i.e. the material model has little knowledge about the fibers or matrix constituents that make up the composite. A full understanding of the average stresses and strains at the element, lamina, and constituent scales requires methods to relate stresses or strains at one scale to those at another scale. Techniques used to bridge these scales are briefly presented here along with initial results comparing results using the modeling approach to ballistic impact data found in the literature. The simulations shown here are of dry fabric layups, which are conceptually and computationally simpler, but some initial discussion of how the techniques apply to full composites is also presented.

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