BUCKLING OF MULTIPLY DELAMINATED BEAMS

An analytical model is developed for buckling of multiply delaminated composite beams or long plates under cylindrical bending, and their interactive effects are studied. The prebuckling and buckling equations, formulated for one-dimensional cases with an arbitrary configuration of through-the-width cracks, are solved in a closed-form manner. The effects of crack length and location are studied, showing different trends of behavior for global and local mode shapes, including a decrease in the buckling load when cracked zones overlap. In some cases, where inadmissible interlaminar penetration in the first mode is involved, higher eigenvalues and the corresponding eigenmodes are needed to define the buckling state. In other cases, where all eigen modes exhibit penetration, the present model can be used only as indicated for the behavior, and a nonlinear analysis with contact constraints is called for. Considering the scanty work done to-date in the field of multiply delaminated beams, the proposed model-even though restricted to a contactless situation-can also serve as the basis for more general nonlinear analysis. A parametric study of several beam configurations is presented through examples.