Stiffeners attached to composite panels and shells may significantly increase the overall buckling load of the resultant stiffened structure. Initially, an extensive literature review was conducted over the past ten years of published work wherein research was conducted on grid stiffened composite structures and stiffened panels, due to their applications in weight sensitive structures. Failure modes identified in the literature had been addressed and divided into a few categories including: buckling of the skin between stiffeners, stiffener crippling and overall buckling. Different methods have been used to predict those failures. These different methods can be divided into two main categories, the smeared stiffener method and the discrete stiffener method. Both of these methods were used and compared in this thesis. First, a buckling analysis was conducted for the case of a grid stiffened composite pressure vessel. Second, a buckling analysis was conducted under the compressive load on the composite stiffened panels for the case of one, two and three longitudinal stiffeners and then, using different parameters, stiffened panels under combined compressive and shear load for the case of one longitudinal centric stiffener and one longitudinal eccentric stiffener, two stiffeners and three stiffeners. / Master of Science

This master´s thesis deals with the issues of electroerosive machining material used in aerospace industry. The master´s thesis is divided into the theoretical and practical part. In the theoretical part is described electroerosive machining with a focus on electrical discharge sinking. One section of the theoretical part is an analysis of materials used in the aerospace industry. The practical part of the master´s thesis is focused on electrical discharge sinking of aerospace material INCO 713LC, here is investigated the influence of machining parameters on the surface of the workpiece and tool.