Parameter Identification of Local Nonlinear Components by Optimal Tracking Technique

Engineering structures which are connected by joints often exhibit local nonlinearities, and such structures can be decomposed into a large linear substructure and one or more nonlinear components. It is difficult to model the nonlinear components because of the complexity of configuration and operating mode. Therefore, parameter identification technique is usually used to model the local nonlinear components. Based on the concept of optimal control solution of system identification problem, a method for the modeling and identification of local nonlinear components is introduced in this chapter. The force transmitted by a nonlinear component is expressed as a function of its state firstly. Then, the technique of optimal tracking is used to identify the force and the states of the nonlinear component. To solve the optimal tracking problem numerically, the precise integration method is employed and introduced briefly in this chapter. After this, parameters of the component can be identified by the least squares parameter estimation method. The precondition of the proposed method is that the model of large linear substructure is known, and actually, it is not very difficult to obtain this model by finite element method. Numerical simulation examples are also given to validate the effectiveness of the proposed method.