Non linear finite element model validation of a lap-joint

It is commonly accepted that bolted structures can present nonlinearities caused by contact conditions, and that these are severely exercised for large vibration amplitudes. Several researches have targeted these joints’ nonlinear behaviour and experimental model validations have demonstrated to be successful. An earlier publication of the authors demonstrates that nonlinearities identified in modal space can be correlated with the same ones identified in the physical space using the reverse path method. A dumbbell test rig was designed and manufactured so as to have two lap joints connecting the two weights placed at either ends of the bolted beam. The test structure was modelled by both two degrees of freedom lump parameter model and Finite Element. The nonlinearities were identified in the first stage of this research work and validated by using a simple spring mass model. The objective of this paper is to show how to model the nonlinear dynamics of the dumbbell test structure using a standard FE package. The validated nonlinear characteristics of the lap-joint will be modelled in the FE environment and prediction of nonlinear responses will be correlated with the experimental ones.