Local Delamination Buckling of a Laminated Beam Caused by Bending.

Abstract

Three- and four-point bending of a layered beam with a delamination are analyzed on the basis of classical beam theory. Axial tensile and compressive forces are induced by bending in the parts of the beam above and below the delamination. When one of the constituent beams is thin enough, the axial compression causes local delamination buckling. The problem of determining the critical buckling load is reduced to the solution of a characteristic equation. The critical load and the relation between the magnitude of the applied load and the deflection at the point of load application predicted from the analyses are shown to agree well with experiments. The nonzero energy release rates are also predicted for four-point bending, which implies that the delamination can spread via local buckling.