Enhancing magnetorheology with precession magnetic fields

We demonstrate a new route to enhance magnetorheology using precession-like magnetic fields. This field configuration is generated by the superposition of a 2D rotational field applied orthogonal to a uniaxial DC field. Maintaining a columnar linear chain structure when applying a precession field was determined to be integral in increasing the average cluster size of the aggregates for low precession angles and a low Mason number. A yield stress increase was experimentally observed when reapplying a uniaxial DC field following the application of a controlled low-angle precession field indicating a favorable structural evolution had taken place under the unsteady field configuration. Experimental results of small-amplitude oscillatory shear tests and shear rheograms are supported by particle-level simulation 3D models and start-up tests. (c) 2021 The Society of Rheology. https://doi.org/10.1122/8.0000356