Abstract
Efficient schemes to represent mathematical model of thin-sheet metal structures jointed by bolted joints for accurately predict the structure dynamic behaviour has been a significant unresolved issue in structural dynamics community. The biggest challenge is to efficiently incorporate the joints local deformation effects on the developed mathematical model via finite element (FE) method. Generally, the joints local deformation typically exerts on the joints mating area. To solve this issue, this paper proposes efficient schemes to represent mathematical model of thin-sheet metal structures jointed by bolted joints with application to accurately calculate the structure dynamic behaviour using FE model updating method. The initial FE model of the assembled structure was developed by employed Fastener Connector (CFAST) in MSC NASTRAN software to represent the bolted joints while, the inclusion of the local deformation effects at the bolted joints mating area was represented by contact elements. Then, the responses obtained from the FE model was evaluated by weight up with experimental data. FE model updating (FEMU) method then was utilised for minimising prediction discrepancies originated from the initial FE model based on the experimental data. The proposed scheme shows the accuracy of the initial prediction was improved from 25.03 % to 14.65 % while the accuracy of the predicted mode shapes via modal assurance criterion (MAC) analysis were above 0.8. Therefore, the findings offer useful schemes for improving the quality of predicted dynamic behaviour, particularly in the thin-sheet metal jointed structure and the developed model can be used with confident for any subsequence dynamic analyses.
Highlights
Bolted joints have been widely used as jointed mechanism for assembled automotive structures
The relative error obtained from the developed finite element (FE) models were systematically minimised using FE model updating (FEMU) method with Experimental modal analysis (EMA) of the structures under investigation were used as reference in respectively cases
The modal assurance criterion (MAC) values recorded for the initial FE models shows acceptable similarity between mode shapes of EMA and the initial FE results of Thin-Plate 1 and Thin-Plate 2
Summary
Bolted joints have been widely used as jointed mechanism for assembled automotive structures. The problem is that improving the predicted model of the bolted joints remains to be difficult and challenging. Numerical analysis such as finite element (FE) method is a practical computational tool that are widely used to provide initial solutions to the engineering problems and are becoming increasingly popular in engineering design and analysis to predict the initial dynamic characteristic of structure [6]. The predicted result from initial FE model of the bolted joined structure is often found to be inconsistent with the experimental data This is due to the input data of the initial FE model are made based on nominal value [7,8,9,10]. The factors of over simplification on the jointed properties such as local geometry features, boundary conditions and inaccurate of joints modelling affects the quality of the developed FE model
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