Dynamic analysis of structure with bolted joint and identifying joint parameters

Sahu, Nagesh Kumar and Pandey, Ashok Kumar (2018) Dynamic analysis of structure with bolted joint and identifying joint parameters. Masters thesis, Indian Institute of Technology Hyderabad.

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Abstract

Bolted joints are common method used to assemble various parts of the structure or machine com- ponents. This joint works well under static condition (static loading). Under dynamic condition, this joint plays very important role. The natural frequencies of the structure reduce because of joint. When comparing with similar structure without joint, we can observe a reduction in natural frequencies for all vibration modes. Hence this could be major source of damping because of which natural frequencies get reduced. The amount of energy dissipation between the joint can be found by hysteresis loop in which force is taken on the ordinate and displacement is taken on the abscissa. We need very �ne mesh to capture energy dissipation between interface to predict the complete be- havior of the joint. This dissipation is because of the micro slip and macro slip happening between the interface of the structure at the joint interface. Various friction model available to predict the energy dissipation at the interface, Iwan and Masing model are few of them. The detailed �nite element analysis of the structure with bolted joint had done on the ANSYS workbench to get the hysteresis loop. To identify and analyze the bolt parameters, Euler-Bernoulli beam theory have been employed in deriving the equation of motion of the beam connected by bolted lap joint by replacing the bolt with a spring and damping element. Multiple scale method is used to solve the equation and results are obtained using MATCONT-a continuation software for bifurcation analysis. To identify parameters, experiments are performed. By comparing the analytical results with experiments, parameters can be identi�ed. The e�ect of gap at the joint have also been studied experimentally and numerically which is very important under varied range of applications. The models developed in the paper can be used further to identify parameters of Masing/Iwan models. v

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