Effect of nesting of fiber bundles on micro fracture of laminated woven fabric composite

In laminated woven fabric composites, fiber bundles do not pack tightly because there are resin rich regions caused by crimp of fiber bundles. The fiber bundles in one layer are often fitted into the neighboring layer, which is called nesting. In this study, the effect of nesting by laminating on mechanical properties and micro fracture behavior of composites was investigated. Tensile testing of woven fabric composites with different number of layers and observation using optical microscopy were performed. With the increase of number of layers, nesting is more likely to occur, resulting in a decrease in thickness per layer increase in fiber volume fraction. This also lead to an increase in modulus and strength but a decrease in knee point stress. The locations at which cracks occurred were different in specimens with and without nesting.