Papers by Author: Rômulo Pierre Batista Dos Reis

Abstract: The relevant and unique thermomechanical properties of shape memory alloys (SMA) have motivated researches for applications in several fields of engineering. The pseudoelasticity and shape memory effect (SME) are some behaviors displayed by these functional materials. The aim of the current work is the manufacture, physical characterization and investigation of electro-thermomechanical response of a SMA copper-based cylindrical element aiming the development of a smart electrical connector. The cylindrical element was manufactured by plasma melting and injection molding of a CuAlNi based SMA. During thermal activation, the SMA cylindrical element presented satisfactory movement of closure through the recovery of its shape, demonstrating a strong potential to generate normal contact forces useful for electrical connections.

Abstract: The possibility of uniting two or more different materials to obtain structures capable to feel and adapt to environmental alterations and operational conditions, has been leading to the development of active composites with functional properties that makes possible the control of shape, vibration, rigidity and/or structural integrity monitoring. These characteristics are very well accepted in modern technological applications. In this context, active composites were manufactured using pre-impregnated (Pre-Pregs) of carbon fiber reinforced polymer (CFRP) and NiTi shape memory alloy (SMA) thin wires in different conditions. The functional capacity of the obtained CFRP-NiTi smart composites was verified through detection of buckling and thermal contraction/expansion effects by electrical heating of the NiTi wires inside the CFRP matrix. Although the NiTi wires represent a minimum volumetric fraction in the CFRP-NiTi produced systems, its influence was evidenced.

Abstract: Shape memory alloys (SMA) are thermo-responsive materials where deformation can be induced and recovered through temperature changes. Therefore, SMA are considered smart materials. In this work, an epoxy beam reinforced by NiTi SMA wires was developed. This active composite contains five pre-trained NiTi SMA wire actuators, evenly distributed along the neutral plane of the epoxy beam, which can be activated by resistive heating. The results of different ways for electrical activation of the smart composite in a simply clamped mode are discussed. It was possible to demonstrate the viability of this concept for attenuation of mechanical vibrations by controlled electrical heating of the NiTi wire actuators.