A methodology to reproduce postbuckling in composite panels to study skin stringer separation

A building block pyramid is designed used to evaluate a composite aircraft structure, combining tests and analyses, using stiffened panels, single-stringer specimens and coupons. Failure in these structures can be caused by postbuckling-induced skin-stringer separation, which is complex, involving matrix cracks, fibre bridges, and delamination...

A perturbation approach for geometrically nonlinear structural analysis using a general purpose finite element code

In this thesis, a finite element based perturbation approach is presented for geometrically nonlinear analysis of thin-walled structures. Geometrically nonlinear static and dynamic analyses are essential for this class of structures. Nowadays nonlinear analysis of thin-walled shell structures is often done using finite element based incremental...

Multilevel design optimization of composite structures with blended laminates

This research work deals with the design and optimization of a large composite structure. In design of large structural systems, it is customary to divide the problem into many smaller independent/semi-independent local design problems. The use of composite necessitates the inclusion of ply angles as design variables. These design variables are...

Thermal and structural performance of tow-placed, variable stiffness panels

The structural response of two variable stiffness composite panels under thermal and mechanical loads are characterized using experiments and analyses. These panels are advanced composite structures where the fiber angle varies continuously within each ply, and are manufactured using an advanced tow placement system. Both variable stiffness...