对一棵柳树在力锤激励和自然风激励条件下进行了模态识别与分析，发现力锤激励时的模态识别结果缺失了部分模态，而自然风激励条件下能较好的识别柳树的主要模态。通过综合两种激励下的模态识别结果，确定了柳树实测的前十阶模态。根据实际柳树的形状、采取合理的材料参数，对该柳树构建了有限元分析模型，并进行模态分析，得到了其前十阶自振频率和振型，发现柳树在各阶振型处主要为树枝的振动，而树干振动较小。最后进行了有限元分析结果和实测结果的对比，发现两者间有较好的对应关系，说明柳树有限元模型的构建是正确的，发现柳树的树冠结构对柳树结构动力特性有着巨大的影响。
Abstract
The modal identification and analysis of a willow tree under force excitation and natural wind excitation were carried out, and it was found that part of the modal identification results under force excitation were missing while the main modes of willow tree could be better identified under natural wind excitation. With synthesizing the modal identification results of the two excitation, the first ten modes of willow tree were determined. Based on the actual willow shape and reasonable material parameters, a finite element analysis model was constructed for the willow tree, and modal analysis was carried out to obtain the first ten natural vibration frequencies and vibration modes of the willow tree. It was found that the vibration of the willow tree was mainly the one of the branch, while the one of the trunk was relatively small. Finally, the comparison between the finite element analysis results and the results of actual measurement showed that there was a good correspondence between them, which indicated that the construction of willow finite element model was correct, and the canopy structure of willow had a great influence on the dynamic characteristics of willow structure.
关键词
树木 /
力锤激励 /
自然风激励 /
有限元 /
动力特性
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Key words
trees /
force hammer excitation /
natural wind excitation /
finite element /
the dynamic characteristics
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