Energy efficiency of shape memory alloy

• Main Author: Yeo, Kai Yan.
• Other Authors: Liu Yong
• Format: Final Year Project
• Language: English
• Published: 2014
• Subjects: DRNTU::Engineering::Mechanical engineering
• Online Access: http://hdl.handle.net/10356/55258
• Institution: Nanyang Technological University

This project is to investigate the energy efficiency of shape memory alloys (SMA) and the factors influencing the efficiency. In order to determine the energy efficiency, mechanical testing and thermal analysis are done to do so. The material used in this project will be the Nickel Titanium (NiTi) wires. The energy efficiency is calculated by determining the amount of work output by the NiTi wire divided by the amount of heat input into the NiTi wire. The method used in the project is joule heating where current and voltage is passed through the wire to generate heat so as to cause phase transformation. SMA are special kind of alloys that can change in shape or length during heating and cooling. This is because of the shape memory effect (SME) it has. SMA are used in applications in real life that can be easily converted between mechanical, heat and electrical energy. However, SMA has major limitations in which it has poor energy efficiency and poor fatigue properties, in which energy efficiency is being investigated in the project. The properties that will be taking into consideration as the energy efficiency influencing factors would be the transformation temperatures, recovery strain and stress. The energy efficiency of NiTi wires is studied by varying the prestrain values, stress and power input conditions. Efficiency values of 1% to 4% are reached for the NiTi wire of diameter of 0.5mm.