# Research on Semi-Active Vibration Control of Pipeline Based on Magneto-Rheological Damper
## 6 Conclusions  
In this paper, the key technology of semi-active control of pipeline vibration based on MR damper was studied. The prototype of MR damper was developed, the dynamic loading test of the prototype was carried out and the dynamic model of MR damper was established. The mechanism of pipeline vibration and the pipeline vibration control algorithm based on MR damper were discussed. The semi-active vibration measurement and control platform based on MR damper was built. The vibration control performances of different pipeline vibration control algorithms were studied experimentally. The conclusions are as follows:  
Figure 18: Vibration characteristics of the different pipeline vibration control modes: (**a**) Vibration level difference of displacement; (**b**) Vibration level difference of acceleration; (**c**) Attenuation rate of displacement; (**d**) Attenuation rate of acceleration.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Method** & \(\mathbf{L_{x}}\) **(dB)** & \(\mathbf{L_{a}}\) **(dB)** & \(\mathbf{J_{x}}\) & \(\mathbf{J_{a}}\) & \(\mathbf{J_{e}}\) \\ \hline Two-state & 15.27 dB & 8.34 dB & 82.27\% & 54.59\% & 91.77\% \\ PID & 18.04 dB & 9.86 dB & 87.01\% & 65.93\% & 95.28\% \\ SMVS & 18.57 dB & 10.77 dB & 87.29\% & 68.15\% & 95.43\% \\ \hline \hline \end{tabular}
\end{table}
Table 5: Vibration level difference of the three control methods.  
1. The transient response of the pipeline system with two-state control has a higher amplitude than the uncontrolled piping system. When the vibration amplitude of the pipeline is equal to the minimum limit of the two-state vibration control, the system exhibits a brief chattering, and the transient process time of the controlled pipeline system is basically the same as that of the uncontrolled system.
2. PID vibration control can effectively control the pipeline vibration during transient phase without system instability and amplitude overshoot. However, when PID vibration control is adopted, the MR damper damping force output has strong pulse characteristics, which will cause a large impact on the MR damper drive control system.
3. In the transient stage, the vibration amplitude of SMVS vibration control system is larger than that of PID vibration control system. In the steady-state stage, SMVS vibration control effect is better than that of PID control, and the continuity of SMVS vibration control force is better than that of PID control and two-state control.
4. The experimental results show that the SMVS vibration control method has the best control effect on the pipeline amplitude and acceleration. The average drop of pipeline displacement is 18.60 dB, the average deviation of acceleration is 13.10 dB, the average attenuation rate of displacement is 87.89%, the average attenuation rate of acceleration is 71.68%, and the average vibration isolation rate is 96.58%.  
Conceptualization, H.J., S.N. and Z.D.; data curation, Y.H. and F.Y.; formal analysis, F.Y.; investigation, H.J., Y.H. and F.Y.; methodology, Z.D.; project administration, S.N.; supervision, S.N.; validation, Y.H. and F.Y.; writing--original draft, H.J.; writing--review and editing, S.N. and Z.D. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the Beijing Natural Science Foundation (Grant No. 3182003), National Natural Science Foundation of China (Grant Nos. 51905011 and 51975010), Beijing Municipal Science and Technology Project (Grant Nos. KM201810005014 and KM201910005033), and CSIC Key Laboratory of Thermal Power Technology Open Foundation (Grant No. TPL2017 BB010).  
Thanks are given to [PERSON] and [PERSON] for their help in prototype design, simulation, experiment and polishing of the manuscript.  
The authors declare no conflict of interest.