Abstract The shear yield stress of magnetorheological fluids is a key parameter for evaluating their rheological performance. In the commonly used cone-plate shear model, the geometric parameter of cone angle significantly affects measurement accuracy. This study combines experiments and numerical simulations to examine how cone angles affect shear yield stress measurement in magnetorheological fluids. A testing device is built using cone-plate with different angles (1–10°). Under a constant magnetic field intensity, the shear yield stress curves of commercial magnetorheological fluids are measured. Finite element analysis is applied to simulate the distribution of magnetic flux density in the cone-plate gap. The results show that a large cone angle causes a nonlinear increase in shear rate at the edge region, leading to local shear-thinning effects that overestimate the yield stress. Additionally, the uniformity of magnetic flux density in the shear gap decreases with larger cone angles. In contrast, smaller cone angles provide better shear field uniformity, and the test results match theoretical models more closely. Finally, a critical threshold for cone angle optimization (1°–2°) is proposed, providing a theoretical basis for the geometric design of magnetorheological fluids testing instruments and data correction.
Liu et al. (Wed,) studied this question.