Frequency-domain subspace identification for nonlinear mechanical systems

• A new method for the identification of nonlinear mechanical systems is introduced.
• This subspace-based method exploits frequency-domain data.
• Nonlinearities are seen as feedback forces exciting the underlying linear system.
• The technique is first demonstrated using two academic examples.
• The experimental identification of a nonlinear beam is then addressed.

This paper introduces a new frequency-domain subspace-based method for the identification of nonlinear mechanical systems. The technique exploits frequency-domain data and interprets nonlinearities as feedback forces exciting the underlying linear system. It is first demonstrated using two academic examples, namely a Duffing oscillator and a five-degree-of-freedom system comprising two nonlinearities. The identification of an experimental beam exhibiting geometrically nonlinear behaviour is then addressed.