Active Composites by 4D Printing
H. Jerry Qi, Associate Professor
George W. Woodruff School of Mechanical Engineering
Georgia Institute of Technology, Atlanta, GA 30332 

Abstract: Recent advances in additive manufacturing allow the precise placement of multiple materials at micrometer resolution with essentially no restrictions on the geometric complexity of the spatial arrangement. Complex 3D solids thus can be created with highly non-regular material distributions in an optimal fashion, enabling the fabrication of devices with unprecedented multifunctional performance. In this work, we exploit these advances and introduce a paradigm of active composites by 4D printing where the shape of printed 3D object can change upon external stimuli, thus offering one additional dimension, time, for shape forming and control. In this talk, we demonstrate this concept by printing shape memory fibers (SMF) composites. We directly print a composite in its initial 3D configuration from a CAD file that specifies the shape memory fiber (SMF) architecture at the lamina and laminate level.  Later, the programmed action of the SMFs creates time dependence of the composite configuration change. This process has considerable design freedom to enable creation of composites with complex and controllable anisotropic thermomechanical behavior via the prescribed fiber architecture, shape, size, orientation and even spatial variation of these parameters. We design and print laminates in thin plate form that can be programmed to assume complex three-dimensional configurations including bent, coiled, and twisted strips, folded shapes (origami), and complex contoured shapes with non-uniform, spatially-varying curvature.

Bio: Dr. Qi received his bachelor and graduate degrees in Engineering Mechanics from Tsinghua University, Beijing, China, and received his doctor degree in Mechanical Engineering from Massachusetts Institute of Technology (MIT) in 2003. After a one year postdoc at MIT, he joined University of Colorado Boulder in 2004 as an assistant professor and was promoted to associate professor with tenure in 2010. In 2014, he started at Georgia Tech as an associate professor with tenure. His current research is in the area of mechanics of soft materials, with a focus on soft active materials, including theoretical and experimental investigation of structure-function relationships of shape memory polymers and elastomers, and arterial tissues. In 2005, he received the Junior Faculty Development Award from University of Colorado at Boulder. In 2007, he received the CAREER award from NSF.