Elastic tailoring effects in anisotropic wing-like structures
MetadataShow full item record
This thesis is devoted to the solution of the buckling, bending and vibration problems of anisotropic wing-like structures. The behavior of isotropic, specially orthotropic and anisotropic wing-like plates under various loadings with various boundary conditions is presented. In particular, plates with all simply-supported, all clamped and wing-like clamped-free-free-free (CFFF) boundary conditions are studied. Problems are solved by using finite element and also eigenfunction expansion approximation methods. The convergence of obtained expansion solutions is studied and it is found that 36 terms in the series of expansion is sufficient for all conditions. We confirm the accuracy of the results by comparing expansion and finite element results for the shear buckling, bending and vibration problems of square and rectangular plates with simply-supported, clamped and CFFF boundary conditions. The influences of the shape of the plate and the anisotropy of the materials on bending and twisting deflection are investigated. For the bending problem of rectangular plates under uniform transverse load, there is no twisting in the plates with 0 and 90 degree fiber orientations while in 45 and -45 degree fiber-oriented plates we can see twisting. The formation and roll-off of vortices is important in flight, so the idea of “feathering” is introduced and defined as the nonlinearity of edge displacements on the edge opposite the root of a CFFF plate. We also show that in the butterfly wing-like plate with 0 degree fiber orientation the deflection reaches its maximum in two opposite points of the edge opposite to the clamped edge, with two ends feathering together. In trapezoidal and butterfly wing-like plates, feathering (one end, two ends together and two ends opposite) is demonstrated by adjusting the fiber orientation direction. In addition, the vibration frequencies and mode shapes were calculated in order to enable investigation of the excitation of selected vibration modes near their resonance.