Edinburgh Napier University

  The last decade has witnessed the emergence of magneto-active polymers (MAPs) as one of the most advanced multi-functional soft composites. An MAP consists of a soft elastomeric matrix filled with micron- or nano-sized magnetisable rigid particles. These magneto-responsive particles are generally classified into two main groups: soft-magnetic particles and hard-magnetic particles. When soft-magnetic particles are used in an MAP, these can be magnetised by an external field. However, such a magnetisation will disappear as soon as the external magnetic field is switched off. In the case of hard-magnetic particles, their magnetisations will largely retain even after the removal of the applied magnetic field. When designing such responsive materials, the choice of both (soft matrix and rigid particles) phases is crucial. In this regard, the stiffness of the polymeric matrix determines the composite resistance to deform under an external magnetic field, i.e., the softer the matrix, the stronger the magnetostriction response. Polymeric materials are widely treated as fully incompressible solids that require special numerical treatment to solve the associated boundary value problem. Furthermore, both soft and hard magnetic particles-filled soft polymers are inherently viscoelastic. In this talk, we will at first present a wide range of experimental studies conducted on soft-and hard-magnetic polymers. Afterwards, we propose a unified simulation framework for magneto-mechanically coupled problems that can model hard and soft MAPs made of compressible and fully incompressible polymers, including the effects of the time-dependent viscoelastic behaviour of the underlying matrix. Finally, using a series of experimentally-driven examples consisting of beam and robotic gripper models under magneto mechanically coupled loading, the versatility and benefits of the proposed framework are demonstrated. The effect of viscoelastic material parameters on the response characteristics of MAPs under coupled magneto-mechanical loading is also studied.