As the operation speed of high-speed train increases, trains with fixed suspension stiffness will encounter dramatical vibrations, especially when its lateral resonance occurs. This greatly affects the ride comfort and safety of the trains. Based on this motivation, a novel stiffness variable suspension system using magnetorheological elastomer (MRE) isolator with negative stiffness is proposed. The controllable stiffness can make the train avoid lateral resonance while the negative stiffness characteristics can provide an actuating force similar to the active control, which further improve the vibration attenuation performance of the suspension. The new MRE isolator was firstly fabricated and tested to verify its stiffness variability, especially negative stiffness characteristics. Four different suspension systems were then tested on a 6-DOF vibration platform for the performance comparison. The experimental results show that this new semi-active lateral suspension system has improve
This paper proposed and prototyped a metamaterial isolator with periodic structure based on magnetorheological elastomer (MRE) and magnet spring. With acoustic metamaterial structure, the proposed metamaterial isolator can generate a stop-band, which means the vibration over specific frequency can't be transferred and will be isolated effectively. Then, with the control of MRE stiffness, the cut-off frequency of the stop-band is tunable, which makes the isolator potential to be adapted to different working situations. The negative stiffness generated by the magnet spring can help to lower the start frequency of the stop-band and enhance the bearing capacity of the metamaterial isolator in vertical direction in the meantime. To verify the feasibility of the proposed device, the magnetic field simulation was first conducted and discussed, and the negative stiffness property of the magnet spring was numerically measured and demonstrated. Then, the mass-spring model of the metamateria
Inspired by the strong nonlinearity of origami cartons, a novel origami-inspired constant-force mechanism (OriCFM) is systematically studied for obtaining a stable quasi-static constant force output. The proposed OriCFM is evolved by adding equivalent springs at horizontal and oblique creases of the rigid origami mechanism. Based on the geometry relationship, the mechanical model of the origami carton is established and its zero-stiffness is obtained. The influence of structural parameters and spring stiffness on the constant force characteristic of the OriCFM is analyzed in detail. By configuring different numbers of horizontal springs, various output characteristics could be observed in the prototype experiment. The case of 4 oblique springs and 2 horizontal springs exhibited partial constant-force output, and the constant-force range accounted for 48.54% of the total experimental stroke. Comparisons of theoretical results with experimental data were carried out to demonstrate the fe
The group of active suspensions with controllable actuating force is noted with their excellent performance in reducing vibrations, however, their demanding requirements for high power consumption and high cost as well as the highly potential instability issue have hindered their practical usage. Semi-active suspensions with controllable stiffness or damping are simple, stable and cost-efficient, but they cannot provide equivalent performance with active suspensions. By incorporating the negative stiffness mechanism into the semi-active suspension using a magnetorheological (MR) damper, this paper provides a solution to improving the vibration-reduction performance of the semi-active suspensions to the level achievable by active suspensions while avoiding the disadvantages of active control. The experimental results demonstrated that the new suspension has brought better vibration-reduction performance than the passive suspension and the conventional MR suspension, and that the vibrati