A method to identify nonlinear element position and its type of a nonlinear system is presented. Nonlinear element position and its type can be identified by an equivalent damping and stiffness matrices which are based on the equivalent linearization technique. The procedures of this technique are: (1) obtain input force and system response signal. (2) define error between the actual and linearized restoring forces. (3) calculate linearized damping and stiffness coefficients to minimize the square error sum.
For the effective identification of nonlinear element position, error matrix method and error vector method are suggested. Several examples show these methods are very effective not only to locate the nonlinear element positions but also to identify the degree of nonlinearity qualitatively.
Nonlinear type can be identified by examining the plots of restoring force vs equivalent state values. Some examples are given to demonstrate the validity of this method.
