Investigations on contact and non-contact based actuation studies of shape memory alloy (SMA) structures and their life cycle behavior

Abstract

In this work different actuation media (contact and non-contact) and its impact on NiTi shape memory alloy (SMA), also called smart material, is presented. The functional properties of a Nitinol (NiTi) component can be augmented by changing the energy source. Thermo-mechanical behavior and morphological analysis have been analyzed. Such approaches are comprehensively investigated for various environments, with the actuation medium (Contact: Electrical and Hot water whereas non-contact: Pulsed laser and continuous fiber laser), as the temperature reaches 50-80ᵒC, SMA gets fully compressed for the first few cycles followed by a loss in actuation. The actuation loss is then studied with different characterization methods such as Thermo Gravimetric Analysis (TGA), Scanning Electron Microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDAX). These studies are required to explain the thermal effect, deterioration, and composition of the impinged surface. Consequently, the present thesis focuses on application point of view and addressed in this thesis for Micro-ElectroMechanical System (MEMS) devices which are Tripod (for Joule Heating), Heat Engine (for Hot water actuation), Array of Micro-valve (for Pulsed laser actuation) and directional control valve (for continuous fiber laser actuation). 1) Life cycle behavior is also investigated for all cases. 2) Precise displacement is measured, and Morphological analysis has been done to verify the outcomes. There is limited published work in the thermomechanical fatigue of SMA, and there is no comprehensive review of this field. A detailed literature review presented in this thesis confirmed the need for significant advancement of the technology. The proposed methodology significantly improves the responsiveness of the complex integrated operations and actuation methodology for decisionmaking. It is concluded that the proposed approach of actuation will serve as the backbone of any next-generation manufacturing sectors.