Effects of curvature on the stresses of a curved laminated beams subjected to bending.

摘要

In aircraft structural applications, curved laminated beam structures are often used as part of the internal structure. If the curved composite structure is subjected to bending that tends to flatten or compress the composite structure, interlaminar stresses can be generated in the thickness direction of the composites. These interlaminar stresses are the major factor of delamination failure. Besides these stresses, the in-plane stresses can be also affected by the pre-existence of the beam curvature.;This research has studied the variation of both tangential and radial stresses with respect to the changing in curvature, stacking sequence, and fiber orientation in a curved laminated beam subjected to a bending moment. Three 3-D finite element models of the curved laminated beam have been developed in PATRAN / NASTRAN. These models have been validated for isotropic material, Al-2014-T6, and orthotropic material, T300/977-2 graphite/epoxy, with all 00 plies lay-up. The finite element models of the curved laminated beam provide solutions showing an excellent agreement with the exact solutions for both tangential and radial stresses.;An analytical method to calculate the tangential stress was also developed for a curved laminated beam subjected to a bending moment. The tangential stress results from this method were compared well with the results from the finite element method. The analytical closed-form expressions of axial, coupling and bending stiffness, as well as their characteristics were also investigated.