Having used particle damping in the column of the milling machine and on the workpiece of the cnc it was time to look at it in detail.
Particle damping works based on impact and friction, depending on the size of the particles this can be one or millions. Studies show that most of the energy is dissipated as heat from shear friction between the particles. Thus absorbing the vibration energy. Hence a bag of sand contains thousands if not millions of particles that interact, friction equals heat and hence damp the vibration.
Particle dampers can be solid, liquid or gas based. An advantage of the particle damper is they can be used in very harsh environments.
When locating a particle damper on a structure it needs to be positioned at the maximum amplitude response.
A sand bag laying on the plate being machined is a very direct application of a particle damper.
Located close to the position of maximum amplitude.
The sand bags in the base of the column may add damping to the vibration generated at the tool face. However, they might be better located at the top of the column where we are likely to see maximum amplitude.
Particle Damping is also known as: acceleration damping, multiple impact damping, multi-particle damping, granular damping, granular-fill damping, and shot damping.
Conclusions
- Energy dissipated through shear friction
- Broadband frequency damper
- Position at the maximum amplitude response
- Can be used in harsh environments
- Solid, liquid or gas based design
- Simple as a bag of dried sand
- Possible to increase the damping of a structure with only a small weight gain
References
- Louis Gagnona, Marco Morandini, Gian LucaGhiringhelli, “A review of particle damping modeling and testing“, Journal of Sound and Vibration, Volume 459, 27 October 2019, 114865
- Zhiwei Xu, Michael Yu Wang, Tianning Chenc, “Particle damping for passive vibration suppression: numerical modelling and experimental investigation”, Journal of Sound and Vibration, Volume 279, Issues 3–5, 21 January 2005, Pages 1097-1120
- Oltmann, J., Hartwich, T., & Krause, D. (2020). “Optimizing lightweight structures with particle damping using frequency based substructuring”, Design Science, 6, E17. doi:10.1017/dsj.2020.13