Determination of Interlaminar Stress Components in a Pretwisted Composite Strip by VAM

Abstract

The interlaminar stress components can cause delamination (separation of laminae), resulting in the failure of material before its elastic limit. Thus, the accurate prediction of the stress components in the composite laminates is vital for the prediction of onset and progress of delamination. Our aim is to analytically arrive at a close approximation solution for interlaminar stress components using recovery relations through 1-D analyses. In this study, the development of an efficient analytical approach to obtain the 3-D elasticity solutions by using recovery relations is achieved. In order to get these stress components accurately, a procedure combining VAM-based framework with approximation method is developed. The approximate method is based upon the stress distribution from more appropriate, sophisticated, and simple polynomials on the equilibrium equation of elasticity. The resulting solution satisfies all the boundary conditions and the compatibility. A parametric study is carried out to understand the nature of 3-D stress components along the thickness of various symmetric, quasi-isotropic, and antisymmetric stacking sequences by this approach. The effectiveness of our approach is demonstrated by comparing the results for interlaminar normal and shear stress components along the interface and through the thickness near free edge under axial strain with those of the available in literature and 3-D FEM for the symmetric, antisymmetric, angle-ply, and cross-ply laminates. This newly described approach shows a good agreement and the computational efficiency. This approach effectively predicts the 3-D stress components with great time-saving.