Multifunctional composites offer the ability to increase the efficiency, autonomy and lifespan of a structure by performing functions that would have been considered by designers as mutually exclusive. In the present perspective paper, a subclass of multifunctional composites is considered: metamaterials. In this perspective, a multifunctional composite is defined as ‘made of two or more materials that perform two or more functions in a manner that is constructive to the overall purpose of the structure’ where there is no differentiation between structural or non-structural functions. Equally, we define metamaterials are a class of man-made structures that display properties that are opposite to those typically found in nature. These ‘engineered’ architected materials continue to revisit and extend the boundaries of traditional materials science, opening up a wealth of new opportunities impacting on all aspects of human life. In our work, multifunctional metamaterials are delineated: electrodynamic, acoustic and mechanical. We review the current progress in these types of multifunctional metamaterials in terms of their bandwidth, fabrication techniques and applicability; noting that lattice structures offer considerable potential across all three functionalities. It culminates in the discussion of three key challenges which are seen by the authors as critical in the development of the next generation of lattice-type multifunctional metamaterials; namely, bandwidth, fabrication technique and proof of applicability. Success by the scientific community in these areas will lead to 3D multi-scale and multimedia lattice frameworks capable of influencing all three types of waves instantly; such a system would be a major technological breakthrough and will redefine our concept and understanding of multifunctional metamaterials in the next 10–20 years.

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Tow-steered laminates, those in which the fiber angle varies as a function of in-plane coordinates, represent a substantial numerical modeling problem. In the Continuous Tow Shearing (CTS) process, the tows are deformed by in-plane shearing that generates a non-linear orientation-thickness coupling, which needs to be accounted for when analyzing CTS structures. In this manuscript, an investigation into the Finite Element discretization of CTS structures is conducted to ascertain the most appropriate element choice in terms of computational cost and accuracy. First, natural frequency and buckling eigenvalue analyses are conducted on constant-thickness flat plates and thin-walled cylinders ([±45/0/90] s layup), in order to set a baseline. Next, multiple discretization strategies are implemented to investigate a CTS plate and a thin-walled CTS cylinder by means of two-and three-dimensional shell elements, in linear frequency and buckling analyses. Two CTS stacking sequences are considered, with the first ([±0 0|70 10 ] 2s ) having identical steering across plies, and the second with variable steering across plies ([±0 0|70 10 /±90 0|70 10 ] s ) to increase the discretization difficulty. The use of three-dimensional shell elements allows for greater fidelity in representing the geometry of a CTS structure, as they allow the asymmetric thickness build-ups to be discretized accurately. We show that three-dimensional shell elements enable the use of lower mesh resolutions whilst maintaining solution accuracy, in comparison to two-dimensional shell element meshes of the same geometric in-plane resolution. Moreover, a relation between element type and mesh resolution is presented to appropriately align element centroids and nodal coordinates, for two-and three-dimensional shell elements, respectively, with the maxima of a specific thickness distribution.