4D-printed structures with tunable mechanical properties
Smart Materials in Additive Manufacturing, volume 2: 4D Printing Mechanics, Modeling, and Advanced Engineering Applications
Three-dimensional (3D) printing allows for significant simplifications in the design cycle through the obvious ease with which complex geometries can be manufactured. However, the resulting components have a fixed set of properties that depend on the geometric design and inherent material properties of the printing material. Four-dimensional (4D) printing relaxes this rigidity in geometry and structural characteristics and provides means to alter and tune the resulting response. The tunability in properties can be achieved through various routes. This chapter is focused on 4D printing structures with programmable properties through the use of shape memory polymers. The chapter provides a comprehensive assessment of the challenges associated with the use of this smart material including dimensional stability issues and incomplete local recovery. The complex interactions between material deposition direction and dimensional changes and shape recovery are also highlighted and discussed. In addition, both simple structure and complex metastructure (two-dimensional (2D) auxetic cellular solid) cases with tunable mechanical properties, structural stiffness, and Poisson’s ratio are presented and thoroughly discussed. This chapter also sheds insight into the functional fatigue properties of the 4D-printed structures following multiple programming (tuning) and recovery cycles. Overall, the detailed experimental results and analyses presented in this chapter provide a deep insight into the properties, challenges, and future research and optimization need to further improve the mechanical properties of thermoplastic 4D-printed structures.
Open Access Status
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