posted on 2020-12-28, 15:34authored byHongzhi Wu, Ouyangxu Wang, Yujia Tian, Mingzhe Wang, Bin Su, Chunze Yan, Kun Zhou, Yusheng Shi
Components fabricated by four-dimensional
(4D) printing hold the
potential for applications in soft robotics because of their characteristics
of responding to external stimuli. Grippers, being the common structures
used in robotics, were fabricated by the selective laser sintering
(SLS)-based 4D printing of magnetism-responsive materials and tested
for remote-controllable deformation in an external magnetic field.
A composite material consisting of magnetic Nd2Fe14B powder and thermoplastic
polyurethane powder was selected as the raw material for the SLS;
the magnetic particle acquired permanent magnetism by magnetization
after the SLS process. Microscopic characterization showed the homogeneous
dispersion of magnetic particles inside the polymer matrix. The magnetic
induction intensity distribution was systematically investigated by
both experiments and numerical simulations. The reliability of the
numerical model proposed was justified by the excellent consistency
between them. The deformation of the grippers could be regulated by
tuning the magnetic particle content and the distance from the external
magnet; the deformation mechanism is investigated numerically. The
magnetic driving force and the corresponding horizontal displacement
are calculated, thus having high accuracy compared with the existing
research that obtained the deformation amount by only visual inspection.
Mechanical properties of the SLS-fabricated magnetic polymer composite
specimens were also studied because of their close relationship with
the deformation behaviors. These findings provide guidance for future
research on controllable deformation and driving force calculation
for 4D printing.