SHAPE MEMORY ALLOYS AND POLYMERS: EXPERIMENTAL 1D MECHANICAL CHARACTERIZATION AND APPLICATIONS

Recent advances in materials engineering have given rise to a new class of materials known as active materials. These materials when used appropriately can aid in development of smart structural systems. Smart structural systems are adaptive in nature and can be utilized in applications that are subject to time varying loads such as aircraft wings, structures exposed to earthquakes, electrical interconnections, biomedical applications, and many more. Materials such as piezoelectric crystals, electro-rheological fluids, shape memory alloys (SMAs) and shape memory polymers (SMPs) constitute some of the active materials that have the innate ability to response to a load by either changing phase (e.g., liquid to solid), and recovering deformation. Active materials when combined with conventional materials (passive materials) such as polymers, stainless steel, and aluminum, can result in the development of smart structural systems (SSS). SMAs and SMPs have a unique ability to recover extensive amounts of deformation (up to 8% strain for SMAs and up to 300% strain for SMPs). This Dissertation focuses on a subclass of active materials, namely shape-memory materials; in particular the focus is on the experimental assessment of two one dimensional constitutive models for NiTiNOL, the most commonly used commercially available SMA with application to the development of a new seismic protection device for masonry historical constructions which has been conceived and constructed at the University of Ferrara and on the mechanical characterization of a brand new shape memory polyurethane named DESMOPAN, patented by Bayer Material Science. Experimental tests on NiTiNOL were conducted in the laboratories of the University of Ferrara, the shape memory alloy device has been tested in the laboratories of the University of Florence and experimental tests on DESMOPAN were conducted in the laboratories of the RWTH Aachen University. The interest on these materials is driven by their potential applications in the developing of new anti-seismic dissipation devices for masonry historical buildings.