A main challenge in laminated glass design is determining the degree of shear coupling between the glass piles through the interlayer, which leads to behavior somewhere between the monolithic limit (perfect coupling) and the layered limit (free-sliding glass layers). The warping of cross-sections caused by significant transverse shear strains in soft interlayers makes traditional laminated plate theories based on the plane-section assumption unreliable. Many commercial software packages exist to assist with this, but they often have limitations, particularly with geometric nonlinearities. Some of these programs only incorporate second-order theories, which are insufficient for thoroughly analyzing curved structures. Here, we introduce an in-house developed FEM code, which employs a nonlinear theory based on solid-shell models to overcome these limitations.
Our code applies the quasi-elastic approximation, where polymers are linear-elastic materials with a secant shear modulus depending on temperature and time. The geometrically exact solid-shell finite element approach allows us to use one single element per layer (glass or polymer) in the thickness direction but can also accommodate the multiple sheets in multi-material interlayers, used to impart hybrid characteristics to the laminate. Visual programming tools can import any curved geometry into the model, which approximates elements using displacement nodal values on the top and bottom surfaces of each layer with inherent regularity. An alternative solid-shell model with fewer parameters is derived by enforcing equal finite rotation of the rigid layers at each surface point through a local rotation-free re-parametrization of nodal displacements and by imposing plane stress conditions. This approach, which facilitates coupling with a solid discretization for modelling connections, is based on a straightforward strain measure quadratic in the displacement unknowns, suitable for handling finite strains. Comprehensive numerical examples for laminated glass plates and curved shells with large deflections are included to illustrate the code potentiality.