Analysis of Quasi-Unbalanced Structures Exhibiting Intrinsically Smart Behavior

This paper addresses the development of an intrinsically smart composite spar structure whose intelligent mechanical response is derived from the fiber architecture. Although methods of achieving intelligent twist-bend coupled response are understood in the scientific community, the exploitation of this concept has been limited due to traditional manufacturing technologies. Published work in this area relies on hand lay-up of patches of unidirection tape to create the box-beam which results in longitudinal seams and high stress concentrations at the corners of the box-beams. An additional restraint on the exploitation of these materials is that conventional finite-element analysis cannot adequately model internal material discontinuities in anisotropic, inhomogeneous structures. In response to this problem a novel manufacturing approach was explored which eliminated these discontinuities and produced what is termed a “quasi-unbalanced” structure. Quasiunbalanced box-beams one meter in length were fabricated with different fiber orientations and crosssectional aspect ratios.