Recent Advancements and Future Perspectives of Refined Zigzag Models for the Analysis of Multilayered Composite and Sandwich Structures
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Multilayered composite and sandwich structures are widely used in many engineering fields, including aerospace, marine, energy, automotive, etc. The combination of different materials along with their mechanical properties, results in a material with enhanced properties, e.g. high strength-to-weight ratio, good fatigue resistance, corrosion resistance, and low thermal conductivity. However, the mechanical properties' differences generally lead to a more complex structural behaviour. Due to their intrinsic anisotropy and a significant transverse shear deformability might cause catastrophic failures, such as debonding, delamination, and core crushing in sandwich panels. In the framework of structural theories, the recently developed Refined Zigzag-based theories represent a valid numerical tool to address the response of multilayered composite and sandwich structures. They generally assume the displacement field as the superposition of two main contributions: a global one able to describe the general laminate behaviour, and a local one characterized by a refined through-the-thickness description of the in-plane displacements. This last contribution is described by an appropriate set of zigzag functions characterized by partial enforcement of the transverse shear stress continuity at the layer interfaces. The enhanced-Refined Zigzag Theory (en-RZT) for beams and plates has shown remarkable accuracy in predicting displacement, strain and stress distributions, frequencies and buckling loads. Higher-order models and mixed-variational formulations, including Reissner’s Mixed Variational Theorem and the Hellinger-Reissner functional, have been implemented to enrich the transverse shear and normal stress predictions of thick multilayered structures. Accurate and computationally efficient finite elements have been formulated and compared with other numerical models, 3D solutions and experimental results. This work aims to present some recent advancements in the framework of the Refined Zigzag models for analysing multilayered composite and sandwich structures, to highlight some numerical comparisons and future perspectives to further enhance the model predictivity of more complex lightweight structures, including multilayered structures with 3D printed components.
