Polymer matrix composite materials are utilized for a variety of aerospace applications because of their reduced weight, and versatile material properties. Composite structures may undergo a variety of loading conditions during service life. In order to be used as protective structures, composites are required to resist ballistic impact loading. For these types of applications, it is necessary to have a model that accurately simulates not only the ballistic limit and damage patterns in an impact region, but also the effect of barely visible impact damage (BVID). BVID plays an important role in the design process of many composite structures. In an impact event, a projectile may not penetrate through the composite material, but there may still be a significant decrease in the load carrying capacity of the structure. It is important to be able to simulate the breakpoints in energy when BVID starts to occur, when BVID becomes significant, and when BVID should be considered catastrophic for a given structure. These points will depend on the material and the purpose of the structure. The BVID mechanisms are highly dependent on the material constituents, the structure's layup, the textile architecture, and the shape of the projectile. Specifically, in a braided composite, numerous micromechanical phenomena occur contributing to the ballistic limit, the damage patterns, and BVID.
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