Bending Of Fiber-Reinforced Composite Plate With Delamination Subjected To Out-of-Plane Loading

For the bending of laminated composite plate with delamination subjected to out of plane loading, most of the studies focused on the the dynamic response using numerical approach. While the literatures presenting close-form solutions regarding the foregoing problems are still unavailable due to the difficulty in determining the contact effect at the interface of the delamination. Based on mechanics of composite materials, theories of shells and plates and nonlinear mechanics, this paper analyzes the bending of fiber-reinforced composite lamina with through-width delamination subjected to transversely distributed load. The main contents areThe delaminated composite plate is modeled as four sub-plates. The strain-displacement relationships in each sub-plate are derived from Kirchhoff's assumptions and Von-Karmon non-linear theory, and the constitutive relationships are established using mechanics of composite materials and theories of shells and plates. Introducing a spring to simulate the contact effect between the interfaces of the delamination, the governing equations of the delaminated composite plate undergoing large deflection are set. Based on the four sub-plate model, the definite conditions are acquired by considering the continuity conditions of forces and displacements at the delamination fronts.The asymptotic approach is applied to solve the governing equations. The nondimensional expressions of stress function, the displacement function, as well as the governing equations and the definite conditions, are educed and are expanded with respect to a small perturbation parameter, which is chosen as the nondimensional maximum deflection of the composite plate. The first and second order governing equations are sorted out and solved using separation of variable and the corresponding definite conditions.A computer program is developed to calculate the deflection of the delaminated composite plate subjected to a uniform compression in the transverse direction and to obtain the load-deflection curve. The analytical solutions are compared with the exact solutions for composite plate with no delamination. Furthermore, parametric studies are performed to analyze the effect of delamination depth and delamination lengh on the mechanical behaviors of the plate, such as load-deflection curve. It is found by examining the deflection modes of the composite plate that the contact effect at the interface of the delamination, such as the size and the location of contact area, is determined by the delamination depth and the delamination lengh. The magnitude of the load and the material properties has no influence on it.