Numerical Evaluation Method for Semi-Active Damping Characteristics of a Passive-Type MR Damper with Functional Damping Force

An evaluation method for the damping force characteristics of a passive-type MR damper with functional damping characteristics equivalent to a semi-active damper is developed. Although the MR damper is a fully passive device without any electrical components such as sensors, power supplies, or power controllers, it exhibits a functional variable damping characteristic analogous to that of a semi-active damper. The developed evaluation method consists of static magnetic field analysis and algebraic equations representing the simplified fluid flow, and is executable with a low computational cost. The developed method was applied to the characteristic evaluation of a prototype passive-type MR damper. The obtained analytical results agree well with the measured damping force and the response characteristics of a single-degree-of-freedom system with the damper obtained in a shaking table test. These results indicate that the evaluation method can be effectively used when designing passive-type MR dampers.