Experimental study and mechanism analysis on the effect of pre-curing time on the microstructure and mechanical properties of magnetorheological elastomers under compression

•The revolution of the rheological properties of CIPs/PDMS MRE mixture with respect to the curing time was tested.•The effect of pre-curing time on the microstructures and MR effects of the anisotropic MREs were analyzed.•Three-dimensional particle dynamics model was developed to simulate the particle structure evolution in MRE mixtures.•The effect of particle arrangement on the MR effect of the anisotropic MREs in compression was interpreted by RVE models.•This work demonstrates the possibility to tailoring the microstructure of the anisotropic MREs to improve their MR effect. The effects of the pre-curing time before exposing the carbonyl iron particles (CIPs) filled liquid polydimethylsiloxane (PDMS) mixture to a preparatory magnetic field on the magnetorheological (MR) effects of the magnetorheological elastomers (MREs) were experimentally and theoretically investigated. The anisotropic MRE samples with different pre-curing time were firstly fabricated and their compressive MR effects were tested. The results showed that the longer pre-curing time induces the shorter and more irregular particle chains formed in the MREs, and the sample pre-cured for 20 min showed the maximum MR effect. Then based on the rheological characterization, a rheological model was proposed to predict the rheological property evolution of CIPs/PDMS mixture with respect to the pre-curing time, and a modified three-dimensional (3D) particle dynamics (PD) model was developed to simulate the particle structure evolution in the MRE mixtures under a preparatory magnetic field. The simulation results showed that short chains were first formed owing to the magnetic attraction between the adjacent particles. Then these short chains approached each other to form long chains and even thick chain-like clusters. The later process can be restrained by increasing the pre-curing time, thus more short and incompact particle chains are formed in the MREs. Lastly, simplified microstructure models representing the wavy chains were used to explore the effect of particle arrangement on the MR effect of the MREs under compression. It is found that the wavy chains with incompactly packed particles are beneficial for improving the MR effect owing to the strong transverse magnetic attraction between the neighboring particles. This work demonstrates that PD simulation is an efficiency method to predict the particle arrangement evolution in the MRE mixture, and the possibility to tailoring the microstruct