If the geometry of a structure could be morphed at will, its efficiency and functionality would be greatly improved. For example, an aircraft wing has different optimal shapes for varying velocities; if one could constantly transform the wing structure to respond to the flying conditions, its efficiency would be significantly improved. The same holds true in other fields of Structural Engineering; indeed, efficiency is not only limited to aerodynamics but could also include incidence of light in adaptive solar panels, deployable surfaces, energy harvesting or light control in buildings.
Despite morphing structures being spreading in some areas of architecture and structural engineering, much remains to be done to properly design and implement these systems. In particular, the current research project focuses on designing and realizing shape-morphing structural elements using shells. Indeed, by exploiting displacement amplifications due to geometrical nonlinearities, suitably designed and actuated shells turn out to be a cheap way to get structural systems capable of considerable shape changes. Specifically we will examine several case studies from the theoretical/modelling phase up to the solution of technological problems related to their actual manufacturing.
The research group has more thant ten years of experience and world-wide scientific collaborations in the fields of shape morphing structures, as well as industrial partnerships interested to develop structural morphing technologies.
Morphing structures find interesting applications in aeronautical engineering (variable sweep wing, landing and take-off flaps, air-inlets, retractable landing gears), civil engineering (adaptive skins, smart ventilation and lighting management systems), electrical engineering (bistable switches), architecture (in the field of responsive architecture, with the aim to enable buildings to adapt their form, shape, color or character according to actual environmental). The present proposal is intended to convey the concept of shape morphing structures into these fields.
While minimal applications of the concept of morphing structures and multistability are already in use, the extension to more complex systems seems usually non trivial, since most of the theoretical problems underlying their design, modelling and control are not completely understood. Within this rapidly emerging area of engineering sciences, the main purpose of the present project is to develop the theoretical models and the numerical tools allowing for a deep scientific understanding and for an efficient engineering design of multistable structural devices.
In particular, the project is focused on: 1) basic modelling aspects, since one of our primary aims is the scientific understanding of the fundamental principles related to morphing structures modelling, actuation and control; 2) the actual realization of the morphing elements. The theoretical and technological issues of fundamental research that we intend to face will presumably find interesting applications also in other fields. Namely, expected applications of shape morphing structures encompass a large variety of engineering products from micro-electro-mechanical systems (system relay switches, micro-pumps and micro-motors), to human-scale systems (general purpose actuators, morphing electronic devices), up to large-scale systems (morphing flight aircraft surfaces, deployable structures and antennas). Tangible products derived by these research activities will be constituted not only by a set of prototypes for the experimental validation of the proposed theoretical and computational models but also by the dedicated numerical codes that will be developed to these purposes.
From the scientific point of view, the design of morphing structures with embedded actuation is a problem theoretically and technologically challenging, demanding that two main difficulties are faced: i) taking into account nonlinear effects in the design and modelling process to obtain a structure with a set of assigned stable equilibrium configurations; ii) conceiving efficient actuation and control techniques to drive the transition from one equilibrium configuration to another. The addressed matter is therefore interdisciplinary and involves competences from nonlinear elasticity, mechanics of plates and shells, smart materials and multi-physics couplings, control and system dynamics, as well as skills in problems of computational mechanics. Expected results are the development of simplified low-dimensional models globally equivalent to the dynamics of morphing structures, of computational models for their refined modelling in a completely nonlinear setting, of large-displacements actuators, of suitable control laws able to avoid snap-through instabilities. The aforementioned problems constitute the theoretical foundations for an efficient design, modelling and control of complex morphing structures. We envisage also the realization of experimental prototypes where these aspects are actually integrated together with demonstrative tools for the possibilities offered by morphing structures, and, as a validation for the models, the numerical schemes and the control laws developed.