Higher-order semi-layerwise models for doubly curved delaminated composite shells

This work deals w ith the development and extension of higher-order models for delaminated doubly curved composite shells with constant radii of curvatures. The mechanical model is based on the method of four equivalent single layers and the system of exact kinematic conditions. A remarkable addition of this work compared to some previous ones, is a modified and improved continuity condition between the delaminated and undelaminated parts of the shell. Using the principle of virtual work, the equilibrium equations of the shell systems are brought to the stage and solved by using the classical Levy plate formulation under simply supported conditions. Four different scenarios of elliptic and hyperbolic delaminated shells are investigated providing the solutions for the mechanical fields as well as for the J-integral. The analytical results are compared to 3D finite element calculations, and excellent agreement was obtained for the displacement components and normal stresses. On the contrary, it was found that the transverse shear stresses are captured quite differently by the proposed method and the finite element models. Although the role of shear stresses should not be underrated, they seem to be marginal because the distributions of the J-integral components are in very good agreement with the numerically determined energy release rates.

Automated summary

This work focuses on the development and extension of higher-order models for delaminated doubly curved composite shells, with an improved continuity condition and solving equilibrium equations using virtual work principle and Levy plate formulation. Different scenarios of delaminated shells were investigated, showing good agreement with finite element calculations in displacement and normal stresses. However, there were differences in capturing transverse shear stresses between the proposed method and finite element models.