To provide sufficient damping torque performance for heavy tracked vehicle's suspensions, the design of a novel high-torque rotary magnetorheological (MR) damper with a parallel plate channel, referred to as PPCRMRD, is presented and the prototype of the PPCRMRD is manufactured. The theoretical model of the PPCRMRD considering the Hybrid magnetic fields effect and leakage effects is proposed. The max damping torque and controllable damping torque of the PPCRMRD are tested on the established experimental setup based on MTS rotary test system and compared with the theoretical results based on the proposed theoretical model, the theoretical model ignoring leakage effect and Bingham plastic model respectively. Under the sinusoidal excitation of 0.05 Hz and amplitude of 35°, compared with the theroetical model without considering the leakage gap and the Bingham plastic model, the maximum error of the proposed model is reduced by 11.08% and 40.66%. The tested max damping torque and controllable damping torque of the PPCRMRD under sinusoidal excitation with an amplitude of 35°and frequencies of 0.1 Hz are as high as 2677 and 1711 N m. The research results show that the principle of the PPCRMRD can provide sufficient damping torque as well as a wide range of controllable damping torque and the proposed theoretical model of the PPCRMRD can describe and predict its damping torque performance precisely.
The aim of the present work is to develop an magnetorheological (MR) seat suspension for military vehicles to mitigate dynamic responses of seated occupant in both shock and vibration occasions. The main components of the MR seat suspension are tested and modelled. Subsequently, a mathematical model incorporating the MR seat and a seated occupant is established. The vibration and shock simulations based on the established model are carried out, and the results indicate that the proposed MR seat suspension can significantly alleviate the acceleration responses of the seated occupant under vibration input, and simultaneously possess the ability of reducing the spinal injury risk in the presence of severe impact. The systematic experiments of the MR seat prototype with a 50th percentile male hybrid III dummy are conducted, it is found out that the experimental results are in good agreement with the theoretical simulation results, which demonstrates that the developed MR seat suspension is provided with favourable vibration reduction performance and impact resistance.
Aiming at the problem that the damping coefficient of the traditional hydropneumatic spring cannot be adjusted in real-time, the magnetorheological (MR) damping technology was introduced into the traditional hydro-pneumatic spring with single gas chamber. A new shear-valve mode MR hydro-pneumatic spring was proposed. And its dynamic performance was analyzed based on multi-physical coupling simulation and mechanical property test. Firstly, a structural scheme of MR hydropneumatic suspension was proposed to ensure the original height adjustment function based on the working principle of traditional hydro-pneumatic suspension with single gas chamber. Secondly, based on the design requirements, the parameter of MR hydropneumatic spring damping structure was designed by using MR damper design method. Thirdly, the multi-physical coupling dynamic performance of the MR hydro-pneumatic spring damping structure was analyzed based on the electromagnetic field analysis theory, flow field analysis theory and thermal field analysis theory. The analysis results showed that the designed MR hydro-pneumatic spring has reasonable magnetic circuit structure and excellent working performance. Then, the mechanical properties of MR hydro-pneumatic spring were tested. The results showed that the maximum damping force can reach 20kN, and the dynamic adjustable multiple can reach 6.4 times. It has good controllability and meets the design requirements. Finally, a nonlinear model of MR hydro-pneumatic spring was established based on the elastic force calculation model of the gas and the Bouc-Wen model. The simulation results of the established model agree well with the experimental results, which can accurately describe the dynamic properties of the hydro-pneumatic spring. The proposed design and modeling method of the MR hydro-pneumatic spring can provide a theoretical basis for the related vibration damping devices.
Combining the scientific research project- the study on cable-stayed suspension bridges, with the engineering background of Dalian Gulf Bridge to be built, this paper focuses on the seismic effect of non-linear viscous dampers on Self-anchored Cable-stayed Suspension Bridge. Based on the non-linear dynamic time-history analysis, the parameter sensitivity of damping coefficient and velocity exponent is analyzed. Through the analysis results, the proper dampers are decided. The seismic response result of before setting dampers is compared with that of after setting dampers. The results show that viscous dampers not only can greatly reduce the relative displacement and inner force under seismic effect of key positions of Self-anchored Cable-stayed Suspension Bridge, but can efficiently minimize the damage caused by earthquakes on bridge structure without changing static force behavior, which can provide evidence of seismic design for similar bridges.
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