1. Department of Mechanical Engineering, University of California, Santa Barbara, CA 93106, USA
2. Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109, USA
3. Department of Engineering Mathematics, University of Bristol, Bristol BS8 1TR, UK
4. Department of Applied Mechanics, Budapest University of Technology and Economics, Budapest 1521, Hungary
5. Research Group on Dynamics of Vehicles and Machines, Hungarian Academy of Sciences, Budapest 1521, Hungary