This work is focused on further development of optimization approaches for improving the design of civil aircraft wingbox structures. Several optimization approaches are proposed in this thesis, suitable for global structural optimization of the wingbox layout, shape optimization of wingbox subcomponents and optimal design of steered-fiber composite parts. The parametric structural model of the wing with internal wingbox structure allows significant changes of the internal components layout and adapts automatically to the given wing outer shape. Combined with structural static and buckling analysis together with simplified aerodynamic simulations, the model allows to use global search methods for preliminary layout of wingbox internal structure. Some attention is also paid to the wing box subcomponents optimization using submodeling. In particular, a special parametrization technique is introduced, which enables topology-like optimization of the planar ribs. In addition, a novel method for parametrization and optimization of steered-fiber composite parts is proposed within this work. Fiber angle at each point of the design space is defined to be tangential to a passing-through iso-contour line of an artificial surface. Using a set of control points distributed over the design space, the shape of the artificial surface can be varied, thus also varying the fiber paths. The method is able to accurately handle maximum curvature constraint for multi-layered fiber-steered composites, where the maximum curvature can differ among the layers.weiterlesen