The research group of Jaehyung Ju, a teacher at JI at Shanghai Jiaotong University, proposed the design of magneto-thermal reprogrammable mechanical metamaterials

Recently, the team of Jaehyung Ju, a teacher at JI Shanghai Jiao Tong University, published a scientific paper
entitled "Magneto-Thermomechanically Reprogrammable Mechanical Metamaterials" in Advanced Materials (impact factor 32.
086), a top journal in the field of materials engineering 。 The research team constructed and demonstrated a magneto-thermal drive mechanism that enables unbound, reversible, low-power, reprogrammable and shape-locked deformation
of single material systems by applying structural instability caused by prestress and asymmetric magnetic torque triggered by magneto-thermal coupling on Shape Memory Polymer (SMP).

Magneto-thermodynamic driving mechanism of mechanical metamaterials

Reprogrammable design principles

In order to meet the application needs of future reconfigurable structural materials, smart materials should have the characteristics
of fast response, reversible deformation, shape locking, reprogramming, and interaction.
SMP is commonly used to build smart materials and has great potential
for applications in lightweight but rigid programmable microstructures due to their temperature-dependent reverse stiffness effect compared to other programmable materials such as hydrogels and liquid crystal elastomers.
However, the irreversible disadvantage of traditional SMP deformation severely limits their reconfigurability
as smart materials.
Magnetron deformation, on the other hand, has the advantage of being untethered and responding quickly, but one of its drawbacks is that it requires additional energy input to maintain the deformation
.
Therefore, how to make smart materials have the above characteristics at the same time through structural design and multiphysics coupling drive is an urgent problem
to be solved in the field.

Jaehyung Ju's research team combined magnetic control with the thermomechanical behavior of SMP without synthesizing new materials, so that the two complement each other
.
The research team proposes to couple the local magnetic torque with the prestress of the SMP lattice structure by non-contact drive, and finally show the shape-locked, unbound and reversible deformation
of the SMP lattice structure.
In addition, they propose a new implementation idea for the reprogrammable of intelligent structural materials - combining the asymmetric arrangement of magnetic moments and structural instability, solving the problem of
high power consumption and long time required for reprogramming.
Therefore, this work opens up a new design path
for intelligent metamaterials, soft robots with variable stiffness, multimodal deformation structures, and mechanical computing devices.

Associate Professor Jaehyung Ju is the corresponding author
of the paper.
The first author is Zou Bihui, a doctoral student of JI, and the co-authors are Liang Zihe, Zhong Dijia, Cui Zhiming, Xiao Kai, graduate students of JI, and Shao Shuang
, a graduate of JI College.
This research work was supported
by the National Natural Science Foundation of China, the Shanghai Municipal Natural Science Foundation and the "Scientific Research Incentive Program for Overseas Introduction of Non-Chinese Foreign Teachers" of Shanghai Jiao Tong University.

Background

Jaehyung Ju is an associate professor and doctoral supervisor
at JI at Shanghai Jiao Tong University.
He received his Ph.
D.
from Texas A&M University in 2005 and did postdoctoral research
at Texas A&M University and Clemson University from 2006 to 2011.
From 2011 to 2016, he was an assistant professor
at the University of North Texas.
He joined JI in 2016 and mainly engaged in mechanical metamaterials, 4D printing, non-pneumatic tire design and mechanical theory research
.
He has published as a corresponding author in top journals Nature Communications, Advanced Materials, Advanced Functional Materials and Journal of the Mechanics and Physics of Solids
.
He presided over the National
Natural Science Foundation of China.