Variable complexity design of composite fuselage frames by response surface techniques

Curved frame structures are often used as part of the internal skeletal str ucture in aircraft. Laminated composite materials offer potential weight sa vings for such structures, but composite frames have different and more com plex failure mechanisms than metallic frames. In particular, failure mechan isms involving interlaminar stresses are important in composite structures. Interlaminar stresses can be directly computed from three-dimensional fini te element models, but the computational expense of these models is prohibi tive. In this work, two- and three-dimensional (2D and 3D) finite element m odels are combined to reduce the computational expense associated with desi gning composite frames. A response surface design approach is used to appro ximate the failure response of curved composite C-section frames subjected to an axial tensile loading using a minimum number of finite element analys es. Results are presented for two examples with two and five design variabl es, respectively. (C) 1998 Elsevier Science Ltd. All rights reserved.