The investigation of the dynamic behaviour of a complex assembled structure using the frequency response function based substructuring method

Efficient and accurate analytical representation of bolted joints in an assembled structure for the prediction of the dynamic behaviour of the structure has been a crucial unsolved issue in the finite element (FE) community. 3D modelling of bolted joints, possessing a large number of degrees of freedom, leads to very high computational time. This paper proposes an efficient representation of bolted joints for the prediction of the dynamic behaviour of a bolted structure. The FE model of the bolted joints was developed using CBUSH element connectors for bolt shanks and CELAS element connectors for the stiffness of the members at the affected areas of the bolted joints. The results of the normal modes analysis of the FE model of the bolted structure were in a very good correlation with experimental modal analysis (EMA) counterparts quantified by a range of MAC values between 0.91 to 0.99 for all modes. Finite element model updating was used to improve the accuracy of the FE model of the bolted joints. The updated FE model of the assembled structure was validated with the physical tested structure. It was found that the comparison of the results has shown good agreement. In addition, the natural frequencies and mode shapes predicted from the proposed model have been found to be more accurate than the results obtained from the previous analytical models reported in the literature on bolted joint modelling of dynamic behaviour investigation. The proposed model can be used for a large and complex structure.

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Experimental Modal Analysis Procedure for a Laser Spot Welded Hat-Plate Structure

Zin

Rani

Yunus

et al. 2019

J. Phys.: Conf. Ser.

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Measuring the dynamic behaviour of a structure made from light thin steel sheets becomes arduous as a result of the double impact, local modes and mass loading issues which lead to inaccurate results. In addition, the attachments of accelerometers, selection of suspension types and methods of excitation adopted to the measurement greatly affect the quality of the experimental results. The aim of this paper is to present detailed procedure for the experimental setup of a welded structure made from thin steel sheets. A hat shaped plate and flat plate connected together by several laser spot welds were used for the demonstration of the experimental modal analysis. The laser spot welded hat-plate structure was tested under free-free boundary conditions using impact testing with roving accelerometers and an LMS Test Lab. This work revealed that the proper procedures used for the experimental setup would help dynamicists enhance and improve the quality of the measured results of frequency response function and the results could be confidently used for the validation purposes and updating analytical models.

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The investigation of the dynamic behaviour of a complex assembled structure using the frequency response function based substructuring method

Cited by 4 publications

References 9 publications

Innovative FRF measurement technique for frequency based substructuring method

Innovative FRF measurement technique for frequency based substructuring method

Finite Element Modelling and Updating of a Bolted Structure Using Elements Representing the Stiffness Members, Bolts and Affected Areas of the Joints

Experimental Modal Analysis Procedure for a Laser Spot Welded Hat-Plate Structure

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