Woodruff School of Mechanical Engineering

Faculty Candidate Seminar


Exploring programmability of architected soft materials


Dr. Tian (Tim) Chen


Ecole polytechnique federale de Lausanne in Switzerland


Monday, February 15, 2021 at 11:00:00 AM



Dr. Ting Zhu


Metamaterials are designed to realize exotic physical properties through the geometric arrangement of their underlying structural layout. Traditional mechanical metamaterials achieve functionalities such as a target Poisson's ratio or shape transformation through unit-cell optimization, often with spatial heterogeneity. These functionalities are programmed into the layout of the metamaterial in a way that cannot be altered. Mechanical reprogrammability analogous to that of digital devices, such as hard disk drives, in which each unit can be written to or read from on-the-fly remains elusive. Here, we discuss different forms of mechanical reprogrammability. First, we cast programmability in the material science domain. Namely, we demonstrate autonomous systems through 3D printed shape memory polymers. Second, we interpret geometrical programming as a means to achieve structural deployment to pre-defined shapes. Lastly, we address the core concept of mechanical memory as analogous to digital memory. Specifically, we propose a tileable mechanical metamaterial with stable memory at the unit-cell level. Our design comprises an array of physical binary elements, m-bits, analogous to digital bits, with clearly delineated writing and reading phases. Each m-bit can be independently and reversibly switched between two stable states ,that is, memory, using magnetic actuation. Under deformation, each state is associated with a distinctly different mechanical response that is fully elastic and can be reversibly cycled until the system is reprogrammed. Encoding a set of binary instructions onto the tiled array yields markedly different mechanical properties. We expect this design paradigm to facilitate the development of novel forms of metamaterials.


Tian Chen is currently a post-doctoral scientist at the École polytechnique fédérale de Lausanne in Switzerland. He is co-advised by Pedro Reis from mechanical engineering and Mark Pauly from computer science. His research is at the intersection of computational design, material science, solid mechanics and advanced manufacturing. In particular, he is interested in the design of architected matter and transformable matter. His studied Engineering Science as an undergraduate from the University of Toronto in Canada, M.Sc. in civil engineering from Delft University of Technology in the Netherlands, and PhD in mechanical engineering from ETH Zurich in Switzerland where he received the ETH Medal in 2018.


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