Analysis and Optimization of a Pressurized Mid-plane Asymmetric Noncircular Sandwich Fuselage

Abstract

For efficient cargo space in a global range transport aircraft, a noncircular cross-section fuselage is investigated. The cross-section investigated is a rectangle with rounded corners. In order to minimize the resulting bending stresses, sandwich construction is investigated, and in particular a mid-plane asymmetric construction is studied to utilize bending stretching coupling to minimize these bending stresses still further in the sandwich construction. Traditionally, in almost all cases of sandwich constructions to date, the construction is mid-plane symmetric, i.e. the faces are of the same material and thickness. There are many needs for sandwich constructions using different faces. For example, for a racing boat, one face is subjected to corrosion, the other face is primarily subjected to an internal environment. On the other hand, considering that many advanced composite materials have different strengths and elastic moduli in tension and compression, even if the two faces are made of the same material, different face thickness can provide a superior structure. The governing equations are obtained by applying the Theorem of Minimum Potential Energy and displacements are assumed. Solutions are derived for a non-circular shell, involving a mid-plane asymmetric sandwich construction that are subjected to a constant internal pressure for the structure with flat sides and rounded corners. The shell is simply supported at both ends. Solutions are obtained through piece-wise matching of plate and shell sections.

Crashworthy Composite Fuselage Section Concept for Next Generation General Aviation

“…To compensate for bending stresses originated in the skins by the non-circular shape under pressurization, additional unidirectional tape plies might need to be added in the fuselage hoop direction. Another compensation factor could be the use asymmetric laminate lay-ups [24]. The proposed energy absorbing floor structure implements the already described NASA concept of foam filled cellular beams construction.…”

Optimum Design of Composite Structures: A Literature Survey (1969–2009)

“…514,982 As in most of the studies, the laminate may be required to be symmetric to avoid bending-extension coupling. In some of the studies, 49,50,61,84,91,132,137,138,141,153,165,181,182,193,215,216,224,297,352,450,500,584,614,654,657,711,784,805,806,811,821,826,849,882,1005 unsymmetrical laminates were considered. In many of the studies, laminates are prescribed to be balanced to prevent shear–extension coupling.…”