磁流变液阻尼器响应时间的试验研究及其动态磁场有限元分析

摘 要：首先，试验测试了不同速度和电流变化下，大吨位磁流变液阻尼器的响应时间；然后，对激励电流变化时阻尼器的磁场变化进行了有限元模拟，基于阻尼器间隙内磁流变液剪切屈服强度的变化考察了阻尼器的响应时间，并与试验数据做了比较。最后，研究了涡流和阻尼器电磁回路中电流响应时间对阻尼力响应时间的影响。结果表明，可以用有限元模拟得到的间隙内磁流变液的平均有效剪切屈服强度的时程曲线来研究磁流变液阻尼器的响应时间；电磁响应时间是阻尼力响应时间的决定因素，减小阻尼器中的涡流是缩短磁流变液阻尼器响应时间的重要途径；电流下降时涡流对阻尼器磁路的影响要大于电流上升的情况；无论是上升还是下降，电流初值越小，涡流对阻尼器磁路的影响越大，阻尼力响应时间也越长。研究还表明，缩短电流的响应时间，会带来更大的涡流，并不一定能缩短阻尼力的响应时间。

Experimental study and dynamic magnetic finite element analysis on the response time of magnetorheological fluid dampers

Firstly, the response time of a large-scale magnetorheological fluid damper (MRF damper) under different velocities and currents was tested. Then, the changing dynamic magnetic field inducted by changing electric current was simulated by finite element analysis (FEA). Based on variation of shear yield strength of MR fluid at gap between cylinder and piston, the response time of MRF damper was calculated. The response time between tested and calculated was also compared. Finally, the effects of eddy current and electric current response time on the damper’s response were also investigated. The researches show that, it is effective that using history curve of average effective shear yield strength of MR fluid at gap which calculated by FEA to study response time of MRF damper. The results also show that, electromagnetic response time is the most important factor which influence the response time of MRF dampers, and reducing eddy current is the key method to reduce response time of MRF damper. Moreover, the influence of eddy current is much higher at condition of current decreasing, and with the same skip of current, whether current increase or decrease, the smaller the initial current is, the greater eddy current affect the damper’s magnetic circuit and the longer damping force response time is. Shorten response of electric current, may induce higher eddy current, and not always reduce response time of damping force.