Designing an interactive hinge with shape memory alloys and polymers

Abstract

This research aims to design and simulate a hinge consisting of shape-memory alloys and polymers, which can be actuated along two axes. The hinge consists of a shape-memory body that is actuated externally by shape-memory alloy springs. To achieve maximum deformation, two small single hinges are made, of which the body has the shape of a plate and which are actuated externally by two springs. The two hinges are then stacked, where the second hinge is twisted 90 degrees, so it can move in two directions. Tensile tests of Nitinol wires were carried out to investigate the behavior. Shape-memory springs were manufactured with this Nitinol wire. Then, the springs were deformed, the temperature of the springs was increased in steps of 10 degrees C, and the force was measured at each temperature step. Simulations were also carried out and compared to the force tests. The best type of Nitinol was chosen for the shape of memory wires. A prototype of the hinge was built and tested. First, the small single hinges were tested, where the displacement was documented. The hinge was not deemed energy efficient. Finally, simulations were carried out for the single and stacked hinges, which showed that the results were similar to reality. Hereafter, the range of motion of the stacked hinge is determined.