Non-linear joint parameter identification by applying the force-state mapping technique in the frequency domain

In this work, a method is suggested to identify non-linear joint properties from measured frequency response functions (FRFs) at the non-linear joint connection points of the structure. Nowadays, the force-state mapping approach is frequently used to identify non-linear parameters within a structure. The method fits the time domain joint forces directly to the joint force model. But the method has some limitations in application to complex real structures because it uses a time domain lumped parameter model. In this study, a frequency domain approach is employed in order to overcome the limitations. The proposed method is easily applicable to a complex structure having non-linear joints since it uses each substructure's FRF in the frequency domain. The validity of the proposed method was tested numerically with a 3 dof system having non-linear joints.