This study presents a novel coupling design with adjustable torsional stiffness. Since the torsional stiffness of the coupling can be adjusted, it can potentially be applied to tune the torsional natural frequencies of rotating systems. The presented coupling design provides clear benefits compared to typical flexible element couplings. For applications with typical flexible element couplings with elastomeric inserts, the torsional stiffness can be adjusted by changing the elastomers. However, this often requires disassembly of the coupling, and the torsional stiffness adjustment has to be performed in large increments. In the presented coupling design, the torsional stiffness can be adjusted without disassembly. The torsional stiffness can be tuned to a wide range of stiffnesses and with arbitrarily small increments. The torsional stiffness of the coupling was determined by analytical calculations, FEM simulations and experimentally. In the experimental tests, the torsional stiffness range of the coupling was measured to be between 8–126 kNm/rad. Experimental measurements agree with the calculated and simulated stiffness values. The coupling design was considered to be successful, since the study confirmed that the torsional stiffness of the coupling can be adjusted to a wide range of different values.
1. Eshleman, R. Torsional vibration of machine systems. In Proceedings of the 6th Turbomachinery Symposium, Texas A&M University, Texas. 1977, 13–22.
2. Corbo, M. and Malanoski, S. Practical design against torsional vibration. In Proceedings of the 25th Turbomachinery Symposium, Texas A&M, Texas. 1996, 189–222.
3. Urbanský, M., Kaššay, P. and Vojtková, J. New design solutions of tangential pneumatic torsional vibration tuners. Sci. J. Sil. Univ. Technol. Series Transp., 2019, 103, 183–191.
https://doi.org/10.20858/sjsutst.2019.103.14
4. Lee, K.-H., Park, J.-E. and Kim, Y.-K. Design of a stiffness variable flexible coupling using magnetorheological elastomer for torsional vibration reduction. J. Intell. Mater. Syst. Struct., 2019, 30(15), 2212–2221.
https://doi.org/10.1177/1045389X19862378
5. Wolf, S. and Hirzinger, G. A new variable stiffness design: Matching requirements of the next robot generation. In Proceedings of the 2008 IEEE Internationl Conference on Robotics and Automation, Pasadena, CA, USA, May 19–23, 2008. IEEE, 1741–1746.
https://doi.org/10.1109/ROBOT.2008.4543452
6. Zheng, Y., Zhang, X., Luo, Y., Zhang, Y. and Xie, S. Analytical study of a quasi-zero stiffness coupling using a torsion magnetic spring with negative stiffness. Mech. Syst. Signal Process., 2018, 100, 135–151.
https://doi.org/10.1016/j.ymssp.2017.07.028
7. Choi, J., Hong, S., Lee, W., Kang, S. and Kim, M. A robot joint with variable stiffness using leaf springs. IEEE Trans. Rob., 2011, 27(2), 229–238.
https://doi.org/10.1109/TRO.2010.2100450
8. Li, Z., Chen, W. and Bai, S. A novel reconfigurable revolute joint with adjustable stiffness. In Proceedings of the 2019 International Conference on Robotics and Automation (ICRA), Montreal, QC, Canada, May 20–24, 2019. IEEE, 8388–8393.
https://doi.org/10.1109/ICRA.2019.8793906
9. Gradu, M. and Schlernitzauer, T. L. Stabilizer bar with variable torsional stiffness. Patent US7207574B2, 24 April 2007.
10. Post, R. F. Magnetic bearing element with adjustable stiffness. Patent US8581463B2, 12 November 2013.
11. Ugural, A. C. and Fenster, S. K. Advanced Strength and Applied Elasticity. Pearson Education, London, 2003.
