Multiscale approach to analysis of composite joints incorporating nanocomposites

This study focuses on the benefits of using nanocomposites in aerospace structural components to prevent or delay the occurrence of unique composite failure modes, such as delamination. A three-scale approach was considered to determine the mechanical properties of the nanocomposites. First, the effective carbon nanotube properties were calculated based on the composite cylinder assemblage method. Second, the effective properties of the carbon nanotube embedded in an epoxy matrix were obtained using the Mori-Tanaka method. Finally, the effective properties of the composite lamina were also acquired using the Mori-Tanaka method assuming that the nanocomposite obtained in stage two was the matrix of that lamina surrounding the fibers. These properties were then used to analyze the structural response of a T-section stringer using detailed finite element models. The stringer was analyzed under different loading conditions and assuming different flaw types in the structure. Initial damage was detected via the virtual crack closure technique implemented in the finite element analysis, and it was assumed to be the characteristic variable to compare the different behaviors. It was found that the use of nanocomposites in the manufacturing process of composite stringers would improve the overall performance against unique composite failure modes.