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

本项目涉及塔架和连接的铰接式吊杆在风荷载和旋涡脱落作用下的减振和疲劳分析。在HyperMesh、Ansys和RISA软件中建立了塔架和臂架的三维有限元模型。在不同可能的吊杆构型和加载方案下，进行了全面的振动分析，以识别结构的前10个固有频率和相应的振型。为了验证模型的准确性，将有限元分析得到的铰接式臂架的固有频率与实验结果进行了比较。STRUDES已经进行了实验，并得出了结果。将试验结果与对数减量技术和模态分析相结合，提取了结构的阻尼值。根据有限元模拟、实验和臂架脱涡分析的结果，确定了在什么情况下结构的固有频率是激励的。此外，还对共振激励下的臂架挠度进行了评估。最后，识别出结构在循环荷载作用下发生疲劳破坏的关键构件，并计算其疲劳寿命，以确保结构在50年内正常运行，不发生任何破坏。最后，优化设计合适的减振装置或调谐减振器，以缓解涡流脱落引起的极端振动。

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.