September 20, 2011 § Leave a comment

Some great stuff about vibration damping –

Viscous Damper Control

September 7, 2011 Comments Off on Viscous Damper Control

The improvement of the so called intelligent liquids and viscous dampers based on them has enabled a lot more powerful and versatile shake damping prospects than ever. This kind of semi-active dampers are already utilised in numerous industrial sectors: automobiles, washing machines, bridges, constructing structures to name a few. This is because of the small size and especially to the quick regulation ability they provide: they can be managed in accordance with the precise demands of your shaking system.

This article presents the primary theoretical formula associated with my viscous damper and some considerations in regards to the study of the vibrations. There are various other choices to control the actuator, but I have learned this particular one quick and valuable enough. The technique is not my design and it is applicable to any kind of viscous damper. I give credit to Jeong-Hoi Koo, whose “Groundhook” algorithm or “velocity-based on-off groundhook control” (On-Off VBG) introduced in his dissertation I employed.

Groundhook Rule on Two-Degree-of-Freedom System

The context in which the control law is shown is a two-degree-of-freedom mass-spring-damper system.
The principle of a groundhook control is that the weight whose vibration is attenuated, is hooked to the floor using a damping component. The semi-active component is the controllable, viscous damper that is placed between the shaking wights.
The control law is uncomplicated: when upper shaking mass is shifting up and the lower mass downwards, tension is used to the viscous damper. This brings about a drawing force to the structure weight in direction of the equilibrium position of the system.

Groundhook Law Made simple on Single-Degree-of-Freedom System

However, as a result of a presumption or an approximation, this law is usually made simple. In case the speed of the lower mass is approximated to be very small and at the same phase with the shaking mass constantly, the system might be modelled through a single-degree-of-freedom vibration system. If the higher moving weight is heading upwards and the lower mass stays still, stress is employed to the viscous damper. That triggers once again a pulling force to the structure mass towards the balance position of the system.

Significance of Comprehending Your Shake

To be able to acquire essentially the most out of the damping potential of a viscous damper, you have to thoroughly know your moving system. To put it differently, you will need to take measurments of the vibration of the object accurately to find out the distressing frequencies, their magnitudes and the time prompt when the wavelengths come about (for example three seconds from startup).

Solely once measuring those, you are able to start designing how a semi-active viscous damper would fix the issue. Or perhaps you will determine that a common passive damper is a more viable option. Nevertheless, when integrating smart control algorithms on your solution, you needs to always review the shake system to the bottom.

If you would want to learn more about viscous dampers, take a look at Magnetorheological Damper Laboratory is specialized in demonstrate the highlights of managing a viscous damper.