Application of the flexibility influence function method in the dynamic analysis of composite beams

The flexibility influence function technique is validated as a method for calculating the displacements and the rotations of a laminated beam subjected to a dynamic load, using the first-order shear deformation laminate theory and comparing the results with those obtained by modal analysis and two finite element models (one-dimensional and three-dimensional). The movements (displacements and rotations) were calculated from a single-span beam subjected to a time-variable load with four boundary conditions: clamped-clamped, hinged-hinged, clamped-free, clamped-hinged. A carbon/epoxy crossply laminated beam was selected to avoid bending-torsion coupling. The maximum movements calculated by the flexibility influence function method differs very little from those calculated with the other two models accounted for by the first-order shear deformation laminate theory: modal analysis and the one-dimensional numerical model. The differences in the rotations between the three-dimensional numerical model and the flexibility influence function method are slightly bigger, and could be due to the warping of the cross-section of the beam, which is not included in the first-order shear deformation laminate theory.