# Shunt Damping Vibration Control Technology: A Review
## 8 Conclusions  
Shunt damping technology has been widely studied and it has shown a good potential in vibration control engineering. The major efforts and findings of the recent literature in the field have been focused mainly on piezoelectric shunt damping and electromagnetic shunt damping. When designing the shunt circuit, the electrical feature of the electrical loop changes and this can produce vibration control effectiveness of the mechanical structure. We summarized shunt damping control by combing PSD and EMSD together to obtain some common characteristics of passive and active shunts. A common control principle and the analytical framework of the shunt circuit were established and provide a feasible way to deal with the coupled PSD and EMSD problem.  
As the environment becomes more complicated, the traditional passive and active shunts may not meet the requirements of a system. Consequently, the adaptive shunt may have a great potential in future research. The adaptive negative resistance shunt can be used to change the stiffness of an electromagnetic transducer, therefore it is worthy of further discussions for the variable stiffness structures and absorption application. To date, research on PSD and EMSD has been carried out in depth. Few literature references have been concerned with shunted magnetostrictive transducers. Hence, extending shunt damping technology into other smart structures and investigating the corresponding characteristics is also worthy of discussion.  
Furthermore, a series of design and optimization methods have been developed to establish the relationship between the electrical and mechanical impedance of passive shunts. If a system is equivalent to an impedance, such as mechanical impedance, electrical impedance, and air and liquid impedance, etc. by matching the impedances to a magneto-mechanic transducer, vibrations can be reduced [150]. This technology may provide a novel method for structural vibration control engineering. After years of research, structural vibration control using shunt damping technology has been thoroughly developed. Active shunts can provide a suitable choice for reducing broadband noise response. The combination of energy harvesting technology and vibration control of a shunt circuit,development of the corresponding theory, optimization and experimental method, and discussion of the dual-functional characteristics of shunt damping technology may be future hotspots of this field.  
This work is national natural science foundation of China under grant Nos. 11602223 and 51675488, State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi'an Jiaotong University under grant Nos. SV2016-KF-14 and SV2016-KF-07, Key Laboratory of Space Utilization, Chinese Academy of Sciences under grant No. LSU-2016-01-01, and Science Foundation of Zhejiang Sci-Tech University (ZSTU) under grant No. 16022060-Y.  
[PERSON] and [PERSON] wrote the manuscript; [PERSON] organized the passive shunt circuit section; [PERSON] concluded the active shunts section; [PERSON], [PERSON] provided the figures of the manuscript.  
The authors declare no conflict of interest.