Structural Tailoring and Active Control Methodologies

3.1 Structural Tailoring Technique As revealed in Chaper 2, the boundary-value problem consists of six differential equations of motion (expressed in terms of the displacements wo ,θy,θx ,uo ,vo and φ ), together with the corresponding BCs. Such a set exhibits a complete coupling between the various modes, i.e., primary and secondary warping, vertical and lateral bending, twist and transverse shear. However, the principal goal of structural tailoring lies in the appropriate selection of fiber orientation so as to produce desired elastic couplings between certain modes. One reason for employing advanced composite materials in flight vehicle design lies in the fact that they permit the use of specific lay-up and fiber orientations so as to induce preferred elastic couplings enhancing the response characteristics. The modified local stiffnesses K12 , K13 , K14 , K24 , K43 defined in Chapter 2 are responsible for producing the elastic couplings. In this sense, there are two well-known configurations, which are shown in Fig. 3.1 and Fig. 3.2 that create unique and special coupling effects. The most general governing equations will be specialized to these structural configurations.