Constructive design models for multidisciplinary optimization of fiber composite structures

The paper presents the basic ideas of so-called "constructive design models" and their special formulation for the ply distribution and the fiber orientations of laminated fiber composite structures. These constructive design models describe the layout of a composite structure in a geometrical way. The corresponding constructive (geometric) parameters are defined as design variables for the optimization process instead of the commonly used finite element properties. Constructive models provide a common basis for determining analysis variables of different analyses models, as necessary in a multidisciplinary optimization process. In particular they facilitate the consideration of manufacturing requirements and limitations for fiber composite structures. The special models for the material layout are formulated with regard to a currently developed tape-laying process. By this process it is possible to apply prepreg-tapes along curved courses on double curved surfaces. The developed models make it possible to describe and optimize these prepreg-courses and also the ply distribution. The curvature of the courses and the shear strains of the tapes as well as the drop-off slopes, which all have to be constrained in the optimization process, can be evaluated from the constructive models.