Experimental investigation of clamped stiffened composite cylindrical shells under end load

Stiffened composite structures have many applications in aerospace industry. One of the common loadings imposed to a grid composite structure is transverse loading. Grid Composite Structure is a kind of composite structures composed from two parts. First part is skin and the second part is Stiffener (Rib). Both of two parts are made of composite material. The grid composite structure in this research is composed from helical stiffeners and cylindrical shell. A grid composite cylindrical shell in this research has been made by filament winding process. In this investigation, the clamped stiffened composite cylindrical shell under end load experimentally has been studied. Hence some electrical strain gauges for measuring the strains have been used. The strain gauges are attached to the shell based on the provided plan. As for the main purpose of this study is stress calculation in stiffened composite cylindrical shell, the stress-strain relations for a lamina of an orthotropic material under plane-stress have been used. The most important conclusion of this investigation is that Stiffening a composite shell with helical ribs causes decrease strains and stresses in the shell. The effect in intersection of two ribs on the shell is more sensible.