Simplified Weight Savings Techniques for Composite Panels

Abstract

This paper presents simple techniques to design unstiffened, strength-controlled composite panels while exploiting the high unidirectional strength composites offer. Ply orientations are rotated until the best orientations are found to produce the lightest weight structure. Strength is then aligned to where, and only where, it is necessary. The techniques presented include provisions for the design of panels where the loads are not constant across the length and width of the panel. An important additional consideration is the selection of ply stacking under multiple loading conditions. In an example panel design, the techniques result in a 13% weight reduction over conventional [0 i /90 j /±45 k ] s laminates.

On Laminate Configurations for Simultaneous Failure

“…Transforming the original coordinates (1-2) into the principal coordinates (x-y) where the shear component NX,, vanishes, the principal normal loads become [3] where the angle, a, between the principal and the original coordinates is defined by The in-plane stress-strain relations of the laminate in the principal coordinates are given by where the laminate is assumed to be symmetric with respect to the mid-plane and then, the bending-extension coupling vanishes. In-plane stiffnesses in Equation (6) are rewritten as follows [5][6][7].…”

“…Thus, it is important to tailor laminate configurations for enhancing the strength of composite structures. Some research works have been made on the failure strength optimization of laminated composites [1][2][3][4]. Chao et al [1] have analyzed the optimal fiber directions of angle-ply laminated cylindrical shells under combined loadings.…”

“…Ikegami et al [2] have obtained the optimal fiber directions of [01/02] laminates under combined loadings. Donaldson [3] and Wurzel [4] have developed the simplified design techniques to optimize the failure strength of laminated composites, although they limit their considerations to a simple class of laminates; they also used the principal coordinate system where the shear component of the applied loads vanishes.…”

Layerwise adaptive topology optimization of laminate structures

“…These design variables then are varied continuously either for a whole structural component or as functions of the considered location. Especially the latter kind of optimization with spatially varying lay-up often EC 16,7 842 leads to laminate designs which are theoretically favorable but which are difficult or expensive to manufacture (Fukunaga and Sekine, 1993;Fukunaga and Vanderplaats, 1991;Donaldson, 1983;Huang and Kro Èplin, 1995).…”