Author(s)

F. Romano, G. Gatta & M. Pecora

Abstract

In this work a procedure for the structural sizing of a composite sandwich wing is described. The procedure is named MLISS (Multi-Level Integrated Structural Sizing); it foresees three growing levels of detailed design and integrates the features of different analysis tools: in-house codes written in Matlab and Fortran languages, a commercial structural sizing software and a finite element software. The wing skin is devised in composite honeycomb-core sandwich panels while the spar webs and the caps in solid laminate; MLISS sizes the structure using the external loads determined by an in-house code developed for the aeroelastic analyses (AEDC). In the first level, the wing is considered as concentrated elements: the skin is sized by bending and torsion; the spar webs and the caps by torsion and bending respectively. The skin carries only the in-plane and bending loads; no transverse shear effect is considered (the core thickness is zero): the skin panels are simulated in solid laminate of thickness two times the thickness of a single sandwich face. Elementary theories are applied to determine the internal loads acting on the different structural wing components. In the second level, the internal loads are used to update the wing sizing. The contribution of the honeycomb core for the skin panels is now considered and its optimal thickness is evaluated. In the third level the finite element model is built; the internal FEA loads are evaluated to size definitively the structure by an iterative approach. Applied to a high aspect ratio wing, MLISS has produced satisfying results; moreover the structural weight obtained in the first level is not far from that one obtained in the third level: so for a fast preliminary weight estimation of a composite sandwich wing, only the first sizing level can be applied. Keywords: wing, structural sizing, honeycomb-core sandwich panels, multi-level, integrated, composite material.

Keywords

wing, structural sizing, honeycomb-core sandwich panels, multi-level, integrated, composite material.