Design and testing of a MRF rotational damper for vehicle applications

Abstract

Adaptive dampers are an interesting solution for conjugating the necessity of controllable devices and low power consumption. Magneto-rheological fluids (MRF) can be profitably employed in adaptive dampers because of the significant variation of fluid parameters with magnetic field properties. This paper focuses on the design process of an innovative rotational MR damper specifically created to be placed in the front-wheel suspension of a compact car. The advantages of the rotational damper and the definition of the optimal design are described. The proposed damper significantly reduces several key problems associated with MR devices: the quantity of fluid required, the sedimentation of ferromagnetic particles in the suspension and the abrasion of the seals. In fact, with this solution, low average working pressure, low flow velocity through valves, a wide range of variable damping characteristics, and high durability of the damper can be achieved. Thanks to this innovative component, different new architectures for adaptive suspension systems can be developed to have a planar distribution of the suspension components with a consequent space optimization and size reduction in the vertical direction.

Development, Test, and Mechanical Model of the Leak-Proof Magnetorheological Damper

“…The magnetic field generated by the permanent magnet is used to make the MRF form a strong liquid film, which avoids the wear and liquid leakage of the MR damper. Giorgetti et al (2010) have designed a rotary MR damper, remarkably decreasing MR fluid sedimentation and wear of the seal device, and improving the damper durability. Tu et al (2011) have sprayed a hard alloy coat onto the damper piston rod to improve its rigidity and delay its nicking damage, which can effectively lengthen the damper service life.…”

Design of a Motorcycle Steering Damper for a Safer Ride

“…where τ y is the yield stress, the signum function (sgn) is +1 for a positive argument and −1 for a negative one and η is the apparent viscosity [45]. where A is the area of each blade that separates two adjacent chambers, b is the torque arm of the damper, and rma is the average radius of the shaft blades.…”

“…where τy is the yield stress, the signum function (sgn) is +1 for a positive argument and −1 for a negative one and η is the apparent viscosity [45]. Using the Bingham fluid theory and considering the two flow zones active in this type of fluid ( Figure 5), each flow is expressed as a function of the pressure gradient Δp through the duct.…”

“…The researchers tried also to As a result of its predominantly axial design and a limited radial size, the conceptual steering damper solution was fully integrated into the motorcycle steering tube. The researchers tried also to solve the contact related problems between seals and MRF avoiding the direct interaction between the two: literature showed an increase in the seal wear by the use of this type of fluids [42][43][44][45]. The damper was designed for an endless life when subjected to the time-varying operational loads.…”

“…Previous studies have also noted the problem of wear of the sealing components (e.g., excessive swelling or loss of strength) due to contact between seal and the MRF when the fluid is subjected to the magnetic field. For example, natural rubber or EPDM seem to have poor compatibility with this type of fluid [42][43][44][45].…”