Investigation of a multi-ball, automatic dynamic balancing mechanism for eccentric rotors
K Green1, A R Champneys, M I Friswell
1Bristol Laboratory for Advanced Dynamics Engineering, University of Bristol, Queen's Building, University Walk, Bristol BS8 1TR, UK. k.green@few.vu.nl
Summary
Automatic dynamic balancers (ADB) with multiple balls do not eliminate rotor vibration at low speeds. Practical modifications showed close agreement with theory, but the ADB can worsen imbalance.
Area of Science:
- Mechanical Engineering
- Vibration Analysis
- Nonlinear Dynamics
Background:
- Eccentric rotors often experience vibrations due to imbalance.
- Automatic dynamic balancers (ADB) are used to mitigate these vibrations.
- Previous studies focused on ADBs with two balls; this extends the analysis to multiple balls.
Purpose of the Study:
- To investigate the dynamics of an automatic dynamic balancer (ADB) with an arbitrary number of balls.
- To determine if increasing the number of balls improves balancing performance.
- To analyze a modified partitioned ADB design.
Main Methods:
- Analytical investigation using bifurcation analysis.
- Numerical simulation of a fully nonlinear ADB model.
- Experimental validation using a physical test rig.
Main Results:
- Perfect balancing is not achievable at rotation speeds near or below the rotor's first natural bending frequency.
- A partitioned ADB design showed close correlation between simulation and experimental results.
- The ADB can worsen rotor imbalance at sub-resonant speeds.
Conclusions:
- Increasing the number of balls in an ADB does not guarantee improved performance, especially at lower speeds.
- The partitioned ADB design offers a viable approach for practical implementation.
- Further research into related ADB configurations is warranted.
