Vibration Attenuation and Fatigue Analysis of the Large Flexible Articulated Boom under Wind Load and Vortex Shedding

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This project concerns with vibration attenuation and fatigue analysis of the towers and attached articulatedbooms in response to wind load and vortex shedding. The three-dimensional finite element model of the towersand booms are developed in HyperMesh, Ansys and RISA softwares. A comprehensive vibration analysis isconducted to identify first 10 natural frequencies and corresponding mode shapes of the structure, underdifferent possible booms configurations and loading scenarios. In order to demonstrate accuracy of the model,the results obtained from finite element analysis, in terms of natural frequency of the articulated boom, arecompared with those of the experiment. The experiment has been already conducted by STRUDES and theresults are available. The experimental results along with logarithmic decrement technique and modal analysisare used to extract damping of the structure. The findings obtained from the finite element simulation,experiments and vortex shedding analysis of the booms are used to identify under what circumstances theresonant frequencies of the structure are excited. Furthermore, the boom deflection under resonance excitationis evaluated. At the end, the critical components of the structure subject to fatigue failure, due to cyclic loads,are identified and their fatigue lives are computed to make sure the structure operates properly during 50 years,without any failure. Finally, appropriate vibration damping devices or tuned vibration absorbers will beoptimally designed to mitigate the extreme vibration due to vortex shedding.