A novel passive adaptive magnetorheological energy absorber

Abstract

For traditional magnetorheological (MR) shock absorbers, the damping force is proportional to the square of the impact velocity. The instantaneous peak value of the damping force can easily cause damage to the load structure or human body, which will reduce the buffering efficiency. The viscous damping force is significantly affected by the size of the gap. Therefore, by changing the flow gap under different buffer strokes by presetting, the damping force can be maintained at a constant output in the full piston stroke, thereby improving the buffer efficiency. That is, a large gap is used at high speed and a small gap is used at low speed. The increase of the magnetic damping force at a small gap is applied to compensate for the decrease of the viscous force at low speed. Only constant current needs to be applied during buffering, which can greatly reduce costs. Based on this idea, a novel MR damper based on axial variable damping gap (MRD-VDG) is proposed. The MRD-VDG design method for the constant value output of the damping force in the full piston stroke is discussed and applied. According to the different requirements of the damping force under different piston displacements, the damping gap of different axial position are preset to realize the constant value output of the damping force during the stroke. The damping force under different damping gaps is analytically derived according to the Bingham-plastic nonlinear flow model with minor losses. Combining with the finite element analysis to obtain magnetic fields at different damping gaps between piston and cylinder. To validate the performance of the proposed design method, the prototype of MRD-VDG is fabricated. Damping characteristic test and impact test are performed to measure the damping characteristics of the MRD-VDG under different excited conditions. The results show that the piston displacement history of the damping force in the experiment is agreed well with the displacement history of the desired F-S curve under the assumed speed. The buffer efficiency of the prototype under designed conditions (the ratio of the corrected theoretical constant damping force to the actual peak damping force) exceeds 90%. This demonstrates the effectiveness of the MRD-VDG design. This design method has significant application prospects under impact condition without complex control (such as gun buffer, landing buffer, etc.)

Design and experimental research of stepped bypass magnetorheological damper

“…It was derived that a much higher range of controllable damping force than the conventional one can be provided at low damping force level (Lee et al, 2021). Based on the idea of using a large gap at high speed and a small gap at low speed, a new MR damper based on axial variable damping gap (MRD-VDG) was proposed, and a prototype damper was designed and fabricated to verify the effectiveness of the damper design (Xi et al, 2021).…”

Development of a new magnetorheological impact damper with low velocity sensitivity

“…Bai et al [22] developed an MR damper comprising an inner bypass structure, which can minimise the field-off stroking load and increase the dynamic range. Xi et al [23] designed a passive adaptive MR energy absorber with a varying gap to maintain a constant force in the whole stroke range. The control strategy to improve the impact protection performance of MR dampers has also been investigated by scholars.…”

Vibration control of vehicle suspension with magneto-rheological variable damping and inertia

“…In view of the fact that variable stiffness control is more difficult to be applied to semi-active suspension than the variable damping control, the research of semi-active suspension is basically limited to the research of variable damping control currently (EIMadany, 2007;Goodall and Kortam, 1983;Nagai, 1993). As an important member of semi-active vehicle suspension, the magnetorheological (MR) suspension has attracted wide attention due to its advantages such as rapid response, reversible control, wide dynamic range and low energy requirement (Xi et al, 2021). At present, the MR suspension technology has been primarily and successfully applied in some commercial automobile.…”