Identification techniques applied to a passive elasto-magnetic suspension

• Published in: Mechanical systems and signal processing 2007-04, Vol.21 (3), p.1479-1488
• Main Authors: Bonisoli, E., Vigliani, A.
• Format: Article
• Language: English
• Subjects: Applied sciences; Direct parametric estimation method; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Inelasticity (thermoplasticity, viscoplasticity...); Machine components; Mechanical engineering. Machine design; Nonlinear identification; Passive magnetic suspensions; Physics; Restoring force method; Solid mechanics; Springs and dampers; Static elasticity (thermoelasticity...); Structural and continuum mechanics; Vibration, mechanical wave, dynamic stability (aeroelasticity, vibration control...)
• ISSN: 0888-3270; 1096-1216
• DOI: 10.1016/j.ymssp.2006.05.009

The paper presents an experimental passive elasto-magnetic suspension based on rare-earth permanent magnets, characterized by negligible dependence on mass of its natural frequency. The nonlinear behaviour of this system, equipped with a traditional linear elastic spring coupled to a magnetic spring, is analysed in time domain, for non-zero initial conditions, and in frequency domain, by applying sweep excitations to the test rig base. The dynamics of the system is very complex in dependence of the magnetic contribution, showing both hardening behaviour in the elasto-magnetic setup, and softening motion amplitude dependent behaviour in the purely magnetic case. Hence it is necessary to adopt nonlinear identification techniques, such as non-parametric restoring force mapping method and direct parametric estimation technique, in order to identify the system parameters in the different configurations. Finally, it is discussed the ability of identified versus analytical models in reproducing the nonlinear dependency of frequency on motion amplitude and the presence of jump phenomena.