Construct3D 2018

4D printing is a novel concept that emerges in recent years, benefiting from the rapid development of advanced 3D printing technologies and active materials. In 4D printing, upon external stimuli on demand, a 3D printed part can change its shapes as a function of time, which becomes the 4th dimension of the shape forming process. 4D printing offers the advantages of forming complicated 3D shapes from low dimensional structures, saving printing materials and printing times, etc. These make it suitable for applications including morphing structures, sensors, actuators, and soft robots. In this talk, we start with the concept of 4D printing. We will then illustrate a few methods of how we use the mechanics in photopolymerization to general shape shifting structures. These include a direct 4D printing where we use the residual stress generated during inkjet 3D printing, a digital light printing method where we use the grayscale in digital light processing to control the photocuring-induced residual stress for 2D and 3D structures.  Finally, we discuss the challenge and future directions for 4D printing