A new zig-zag theory for accurately predicting interlaminar shear stress of laminated beam structures

Laminated beams are typical bearing members in the aerospace industry. Excessive interlaminar shear stress (transverse shear stress at the interlayer) is the main cause of delamination failure. The existing laminated beam models can not accurately predict the transverse shear stress for the composite laminated beams with large number of layers and sandwich beams with large differences in material properties. In this study, a new zig-zag theoretical model that can accurately predict the transverse shear stress of laminated beams is proposed by constructing a new linear piecewise zig-zag function. Several typical numerical examples show that the new zig-zag theoretical model has higher calculation accuracy for the composite laminated beams with large number of layers and sandwich beams with large differences in material properties, and can predict the delamination of laminated beams. In addition, the model fulfills a priori the interlaminar transverse shear stress continuous condition at the interfaces and can accurately predict the transverse shear stress of laminated beam without the post-processing of three-dimensional equilibrium equation. The number of unknown variables of this model in displacement field is small. Without the first derivatives of transverse displacement in the displacement field, this model is well suited for developing C0 elements. © 2019, Press of Chinese Journal of Aeronautics. All right reserved.