Design And 3D Printing Of Magnetoactive Smart Metamaterials And Their Magneto-mechanical Coupling Behaviors

The magnetoactive smart materials and metamaterials,based on magnetic micro-nano particle-polymer soft matrix,have shown great advantages and application potentials in many engineering fields,such as software robots,bionic science,biomedical and modern national defense.It is because they not only have the diversified and superior mechanical properties as traditional mechanical metamaterials,but also can implement remote control,fast reversible,multi-modal,complex large deformation and motion driven under applied magnetic fields.And they even have supernormal controllable mechanical properties(such as negative Poisson's ratio,negative modulus,negative stiffness,etc.)as well as shape reconfigurations and locking properties.The new design philosophy of programmable provides a broader development and application prospect for the diversification of functions,performance specificity and structural integration of this type of smart materials,which makes it possible to implement intelligent deformation and motion,environmental adaptability and complex configuration reconstruction driven by applied magnetic fields.In this work,we implemented the laboratory design and fabrication of the cuboctahedron magnetoactive smart metamaterial and the polygon topological metamaterial by design of metamaterial and self-developed "magnetic-domain microelement" programmable preparation technology of magneto-active composite materials based on 3D printing technology.The corresponding experimental tests and magnetic drive performance characterizations were carried out.In order to effectively interpret and characterize the magnetomechanical coupling characteristics and the behavior of the magnetoactive smart metamaterials,the finite element numerical model was further established.The effects of macroscopic geometric characteristics and magnetic domain distribution characteristics on the magneto-induced deformation and magneto-mechanical coupling behaviors of the magnetoactive smart metamaterial were analyzed in depth,and the excellent magnetically controlling magneto-mechanical characteristics and coupling behavior laws were revealed.Firstly,for the soft magnetic particles-rubber soft matrix and isotropic magnetoactive composite material,a cuboctahedron magnetoactive smart metamaterial with remote control,fast reversible,multi-modal large deformation was designed and successfully fabricated,by the means of a simple and efficient fused deposition modeling 3D printing and casting molding technology.Further,for hard magnetic composite soft materials with anisotropy,the programmable and direct writing 3D printing forming technology was implemented,which was based on the self-designed and modified the 3D printing function of the existing polymer soft medium.On this basis,the polygon topological metamaterials with adjustable mechanical properties and programmed of magnetic domain distribution were successfully prepared by the programming design of the macroscopic geometric structure,microscopic "magnetic-domain microelement" distribution and printing path of the magnetoactive composite soft material.Secondly,we experimentally investigated the magneto-induced deformation characteristics of the prepared cuboctahedron magnetoactive smart metamaterial under different magnetic fields.The effects of structural geometric characteristics,material parameters and topological configurations on their magneto-mechanical properties as well as obtained different magneto-induced deformation modes under uniform and gradient magnetic fields and characterized the magnetomechanical behavior of the magnetoactive smart metamaterial under different magnetic fields were discussed in detail.To further analyze the magnetomechanical behavior of the cuboctahedron magnetoactive smart metamaterial,the finite element model of large deformation of magnetoactive soft materials was established,and the numerical simulation results were in good agreement with the experimental data.The experimental and simulation results show that the smart metamaterial exhibited the characteristics of rapid and excellent two-way magneto-induced deformation with a quite remarkable deformation up to 85%,and it could quickly return to the original shape when the magnetic field was removed.The functional application concept of particles transport in a narrow pipe under the coordinated control of a combined uniform and gradient magnetic field was further proposed based on the magneto-induced deformation characteristics of different magnetic fields.The demonstration experiments of the magnetic navigation and magneto-induced multimodal shape change of cuboctahedron magnetoactive smart metamaterial were presented.The related research can provide theoretical guidance for the design,performance improvement and application expansion of magnetoactive smart metamaterial.Finally,the experiment characterization and numerical simulation of the designed and prepared programmable magnetoactive smart metamaterial polygon topology structure were carried out.The rationality and accuracy of the programming design of "magnetic-domain microelement" and the printing path design were verified by the simple structure of extruded magnetoactive wires.Further,the magneto-induced deformation and the negative Poisson's ratio effect of star-shaped and arrow-shaped magnetoactive polygonal topology metamaterials with pre-micro magnetic domain design distribution were studied,and the rich deformation modes and excellent magnetomechanical coupling performance were obtained.The dependency of magneto-mechanical coupling deformation behavior on the geometric parameters and magnetic domain distribution characteristics of the magnetoactive polygonal metamaterials was simulated.In this paper,the magnetoactive smart metamaterials with remote control,fast reversible,programmable,supernormal controllable mechanical properties,multi-modal complex and large deformation properties have been successfully prepared by designing the macroscopic and microstructure of magnetoactive smart soft materials and using new technology.This study may expand the magneto-induced deformation mode,properties and application range of traditional magnetoactive smart composite soft materials,and provides an effective approach and method for the design and analysis of smart metamaterials with multi-function and structural integrated design.