Parameter identification of nonlinear bistable piezoelectric structures by two-stage subspace method

System parameters identification of nonlinear bistable structures has attracted considerable interest because the performance enhancement of energy harvesting and vibration control is significantly dependent on the model parameter of nonlinear systems. Therefore, a two-stage subspace method is proposed to identify the critical parameters in the system equation of nonlinear bistable piezoelectric structures. The dynamic equation of nonlinear bistable piezoelectric structures is separated into an underlying linear electromechanical coupling equation and a nonlinear mechanical equation. At first, for the underlying linear electromechanical coupling equation, a force–displacement subspace is constructed to identify the linear mass, damping and stiffness. Meanwhile, a velocity–voltage subspace is created for the identification of the electromechanical coupling coefficient. Next, for the nonlinear mechanical equation, the nonlinear restoring force in bistable structures can be estimated by the extended nonlinear frequency response function. Numerical simulation on a magnetic coupled bistable piezoelectric structure is performed to investigate the influence of frequency-swept responses, the noise intensity and polynomial order on identification accuracy. Experimental measurement of a magnetic coupled asymmetric bistable piezoelectric beam is conducted under different excitation conditions. Experimental results demonstrate the effectiveness of the proposed identification method.