Magnetorheological dampers (MRD) used in automobiles are usually of small size, and the traditional MRD damping channel features short effective working length and small output damping force, which results in its limited engineering application. To solve this problem, a novel full-length effective MRD with magnetically conductive ring of trapezoidal cross section was proposed to increase the effective working length of the damping channel and slow down magnetic saturation. Based on the rheological properties of magnetorheological fluid and fluid dynamics theory, the design and calculation method of specific structure and magnetic circuit were given. Five MRDs with different structures were compared by finite element simulation. The results showed that: the proposed novel full-channel effective MRD can significantly increase the effective working length of the damping channel, reaching over 99% of the full length; it can also improve the magnetic saturation problem for a small-size MRD; in addition, under the same current excitation and size constraint, the magnetic field intensity distribution of the damping channel is more uniform, the average magnetic field intensity is larger, and the output damping force is larger; the damping characteristics of the new MRD were analyzed and compared with those of the common MRD and the full-length effective MRD with bending magnetic circuit, indicating that the new full-length effective MRD has a larger output damping force while the structure size is smaller. Finally, the LQG controller was used to analyze the vibration reduction performance, showing that the new full-length effective MRD has better vibration reduction performance than the common MRD, and can further reduce the sprung mass acceleration and tire dynamic deformation by 21.51% and 1.43%. This study can effectively expand the practical application range of small-size MRDs and has certain engineering application significance.
