Viscous Fluid Damper (abbreviated as VFD or FVD)

The viscous fluid damper (abbreviated as VFD or FVD) was originally developed in the 1960s, with its initial focus mainly on the aerospace and military fields. At that time, it shouldered important missions such as protecting missiles from nuclear attacks, safeguarding submarines from underwater explosion attacks, and stabilizing the launch platforms of spacecraft. After years of accumulation and technological evolution, nowadays the viscous fluid damper has successfully crossed over to the field of civil engineering and has become a powerful safeguard to protect buildings, bridges and numerous other structures all over the world from destructive impacts and vibrations. Essentially, it is a hydraulic device. Once subjected to external impacts, it can efficiently dissipate the vibration energy exerted on structures by earthquakes, typhoons or others. Its principle is based on the fundamental physical law of conservation of energy. That is to say, the viscous fluid damper ingeniously converts the kinetic energy contained in the structural movement into heat and then gradually dissipates this energy into the surrounding air. VFD has a similar structure to that of a syringe. When relative motion occurs inside the viscous damper, the fluid (damping fluid) therein will start to flow. Especially when the fluid passes through the piston gap, the fluid will accumulate, which will in turn lead to a sharp increase in the internal pressure. Under such circumstances, the piston will correspondingly generate a resistance force, and the kinetic energy of motion will be smoothly converted into thermal energy and finally dissipated into the environment. This resistance force generated by the piston is defined as the damping force. It is worth mentioning that the smaller the diameter of the piston gap and the faster the compression speed are, the greater the damping force will be. Therefore, it is also called a velocity-dependent damper. VFD have significant advantages: They are applicable to various situations such as wind-induced vibrations, minor earthquakes and major earthquakes; They are small in size and can be placed inside decorative walls and integrated with the surrounding environment; They can effectively dissipate energy and reduce vibrations during long-period earthquakes; The influence on the damping force is minimal within the temperature range from -20 °C to 80 °C; They can undergo 100% inspection and can still be put into normal use after inspection; Their performance is usually slightly affected after an earthquake and often there is no need for replacement.