Study On Nonlinear Finite Element Precise Modeling And Model Validation Methods Of Complex Joint Structures

Bolt joints are used universally to connect structures which have contact relationship between their surfaces. Good response prediction of bolt joints in the global structural dynamic analysis requires accurate finite element model. To achieve this, it is necessary to perform model updating and model validation in contact and bolt pre-load cases. In this paper, the model updating of bolt joints are carried out by combination of finite element analysis (FEA) and experimental modal analysis (EMA). The precise model thus obtained is validated by comfirmatory test data.The nonlinear finite element modeling and analysis of a bolt joint are implemented in this paper. Both contact and bolt pre-load cases are considered in the modeling. The influence of bolt pre-loads and contact surface friction coefficients on the pre-stressed modal frequency are discussed. The accuracy of the finite element analysis is verified by EMA. This analysis method is applied to a complex avionic chassis structure to obtained better result.Based on response surface method (RSM), the pre-stressed finite element model updating of the complicated bolt joint is accomplished. The cases studied in the paper showed RSM is an effective tool for rapid modeling and pre-stressed model updating of bolt joints. The steps for finite element model validation of the bolt joint are described in this paper. Uncertainty analysis and transmission methods of bolt joints are also achieved. Based on test data, the model updating of the complicated bolt joint is implemented by intergrated substructure updating and RSM. Validation of finite element model is done to a reasonable criterion as well.