Fabrication and property research of a new 3D-Printable magnetorheological elastomer (MRE)

In order to meet the growing design demands for shape and structure of magnetic functional materials, particularly Magnetorheological Elastomers (MREs), additive manufacturing technology has been introduced into MRE production. Reported works of printable MRE ( p-MRE) have successfully obtained high relative magnetorheological (MR) performance comparable to traditional MRE. However, there are still few studies on p-MRE with both high relative and absolute MR effects that is required for some applications such as intelligent dampers in automotive industry. In this study, polyurethane (TPU) and carbonyl iron powder (CIP) were utilized as raw materials to formulate p-MRE with high printability and high comprehensive MR performance. Based on the fused deposition modeling (FDM) process, a printing strategy suitable for this p-MRE material was determined through experimental design (DOE). The test result showed that the comprehensive MR performance of the p-MRE sheet samples obtained through linear printing path exceeded the majority of previously reported p-MRE materials. In addition, based on the analysis of the correlation between magnetic hysteresis like effect and MR effects, a circular printing path that may be beneficial for improving MR performance was proposed and corresponding p-MRE sheet sample was printed. The test results showed that compared with the linear printing path, the circular printing path further increases the comprehensive MR effect of the sheet sample to a maximum absolute MR effect of 4.2 MPa and a maximum relative MR effect of 620 %, which is comparable to most conventional MRE materials. Additionally, a theoretical framework associating magnetic field strength and filling density was proposed to explain peculiar phenomena observed in the experiments. On the basis of previous research on MREs and filler modified elastomers, a hypothesis was proposed to link magnetic field intensity with filler density, allowing the existing theory of filler modified elastomers to be used to explain the special phenomena observed in our experiments.