Nonlinear Modeling and Identification of Structural Joint by Response Control Vibration Test

Components of mechanical product are assembled by structural joints, such as bolting, riveting, welding, etc. Structural joints introduce nonlinearity to some engineering structures, and the nonlinearity need to be modeled precisely. To meet serious quality requirements, it is necessary to detect and identify nonlinearity of mechanical products for structural optimization. Modal test to acquire a dynamic response has been applied for decades, which provides reliable results for finite element (FE) model updating. Here response control vibration test for identification of nonlinearity is presented. A nonlinear system can be regarded as linearity for particular steady state response, and classical linear analysis tool is applicable to extract modal data for particular response. First, its applicability is illustrated by some numerical simulations. Subsequently, it is implemented on experimental setup with structural joints by shaking table. The stiffness and damping function dependent of relative displacement are fitted to describe its inherent nonlinearity. The spring and damping forces are identified by harmonic balance method (HBM) to predict output response. Based on the identified results, the procedure is recommended that it allows a reliable measurement of nonlinearity with a certain accuracy.