Design and development of 4D printing technique with multi material and multi functionality

Abstract

Additive Manufacturing (AM) technique is employed to build 3D complex objects layer by layer from 3D CAD data (ASTM F2915 2015). In various fields, AM is disruptive, creating prototypes and functional parts. Integrating Smart Materials (SMs) within structures paves the way to develop dynamic, multi-material, and multi-functional structures (4D printed ) that transmute the shape to external triggers, adding another feature. Applications of these products include two-way switches, circuit breakers, Stewart platforms, self-assembly cubes, wing morphing devices, metastructures, actuators, and sensors, with demand spanning industries such as automobiles, electronics, biomedical, and aerospace etc. newline newlineIn the current scenario, demand for Shape Memory Alloy (SMA) based dynamic structures that are cost-effective, more reliable, high force-to-weight ratio, multi-functional, and more durable actuators/sensors is rapidly increasing, and developing such actuators is challenging. Thus, the present study first focuses on building an innovative 4D printer setup capable of printing/building reprogrammable, dynamic, multi-functional structures. Secondly, a built 4D printer setup is employed to develop SMA-based 4D printed bending actuators by integrating various SMA wires with varied compositions (NiTi, NiTiCu, NiTiFe), diameters (Ø1 and Ø0.5 mm), and quantities of SMA wires (1, 2, and 4 Nos.) as hinges with the aid of in-house built novel 4D printing technique. newline newlineSubsequently, research work focuses on assessing the debonding strength of the SMA-matrix interface and evaluating the functional capabilities of the built 4D printed actuators, including the force of actuation, time response, residual strain recovery, and the percentage of displacement of reduction (deformation). The debonding strength results reveal that it can be improved by incorporating multiple SMA wires, changing the end shape, and increasing the surface roughness via chemical etching of the incorporated SMA wires. newline