Finite element model updating of bolted lap joints implementing identification of joint affected region parameters

In this research, the new concept of ‘bolted joint affected region (BJAR)’ is introduced to simulate dynamical behavior of bolted lap joints. Such regions are modeled via special elements called contact zone element (CZE) which unify the neighboring contact surfaces of substructures. These elements are different from the thin layer interface elements that form an individual layer between the two substructures. The CZEs have no specified elastic characteristics. They are thus different from the adjoining solid elements and the constitutive relation for them is prescribed in normal and shear components. The unknown parameters of the model can be identified throughout model updating with modal test data. The structure’s frequency response function (FRF) is measured by excitation with an impact hammer and the measured responses are compared with model predictions including the CZEs’ parameters. The difference between the measured and predicted frequencies is minimized as the objective function. The optimized thickness and density are considered in addition to the elastic properties of BJAR. The competency of the proposed procedure is verified with modeling an actual structure containing a single lap bolted joint coupling two identical structural steel beams. The results showed proper conformity with model predictions. This model can be incorporated into the commercial finite element codes to simulate bolted joints for large and complex structures considering its accuracy and computationally efficient manner.