Superelements for a computationally efficient structural analysis of elliptical fuselage sections

The paper deals with the computationally efficient linear static analysis of cylindrical frame-stringer stiffened fuselage structures. In this regard a special dedicated finite element is proposed, which is a combination of curved beam elements and shell elements. This element is based on classical beam theory as well as on membrane shell theory. It is derived using approach functions that consider the differential couplings between the approach functions and hence allows for larger element sizes. Therefore an analysis can be carried out with only few degrees of freedom and hence the computational time for structural analyses is significantly reduced. An approximation technique is discussed to enable the analysis of elliptical cross-sections using circular elements. The element aids in a computationally efficient analysis of the entire fuselage, without compromising accuracy compared to other conventional finite element softwares. As an example for illustrating the application of the developed element a numerical analysis of an orthogonally stiffened fuselage structure made of a symmetric orthotropic laminate is presented.