On the modeling and design of composite multilayered structures using solid-shell finite element model

•
• We develop a new free-locking Composite Hex-Shell FE, no stabilization is required.
•
• CPU time savings and better results with the Hex-Shell FE compared to 3D bricks.
•
• 3D material law with failure criteria may be used with the Hex-Shell FE model.
•
• New Strategy to reuse the DOE of previous iterations to reduce the FE simulations.
•
• A new RSM involving Diffuse Approximation model and pattern search optimization.

In this investigation a coupling between a 3D solid-shell element for the analysis of multilayered composite shell structures and a specific response surface method is proposed. The first part of the paper is dedicated to the finite element formulation of a developed composite 8-node solid-shell element called SCH8γ7SCH8γ7, based only on translational degrees of freedom. The basis of the present finite element formulation is the standard 8-node brick element with tri-linear shape functions. A particular attention is given to alleviate shear, trapezoidal and thickness locking, without resorting to the classical plane-stress assumption. Assumed natural strain method and enhanced assumed strain method are used to improve the relative poor element behavior of a standard hexahedral displacement element. The anisotropic material behavior of layered shells is modeled using a fully three dimensional elastic orthotropic material law in each layer, including the thickness stress component. The second part of the paper will focus on an adaptive response surface method for the structural optimization problem. The response surfaces are built using moving least squares approximations and design of experiments by means of a specific method called Diffuse Approximation.Several numerical applications to composite multilayered shell structures are studied to show the applicability and effectiveness of the proposed procedure. Good results of analysis and optimization using the developed SCH8γ7SCH8γ7 solid-shell element have been obtained in comparison with reference analytical solutions and with those obtained using the SC8R   solid-shell finite element available in ABAQUS©ABAQUS© code.