Abstract This study investigates the amplitude dependent damping behaviour of the fundamental mode for composite tubes under dynamic excitations. For this purpose, a closed form solution of damping ratio is derived for a cantilever tube subjected to harmonic base excitation while accounting for stress fields, material properties and cross-sectional configurations of the member. Shake table experiments are performed on square, hexagonal and circular woven carbon fibre-reinforced polymer (CFRP) tubes of length 1 m. To measure the responses along the tube length, accelerometers are used. In addition, table motions are also recorded. Based on these measurements, damping ratios are obtained from the experiments for varying levels of excitation. It is found from the experiments that the damping ratio increases with the increase in excitation amplitude. Among the tubes considered, damping ratio is noted to be higher for the square tube in comparison to the circular tube. This is due to the presence of more material near the edges (which is particularly beneficial as stresses are higher at the edges than the neutral axis) for the square tube in comparison to the circular tube. It is also found that the damping ratios obtained from the proposed expression are in well agreement with the experimentally measured values with a maximum deviation of about 10%.

中文翻译：

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CFRP 复合管基模的振幅相关阻尼行为：横截面的影响

摘要 本研究研究了动态激励下复合管基模的振幅相关阻尼行为。为此，在考虑应力场、材料特性和构件的横截面构造的同时，为承受谐波基础激励的悬臂管推导出阻尼比的封闭形式解。在长度为 1 m 的方形、六边形和圆形编织碳纤维增强聚合物 (CFRP) 管上进行振动台实验。为了测量沿管长度的响应，使用了加速度计。此外，还记录工作台运动。基于这些测量，阻尼比是从不同激励水平的实验中获得的。从实验中发现，阻尼比随着激励幅度的增加而增加。在考虑的管子中，与圆管相比，方管的阻尼比更高。这是由于与圆形管相比，方形管在边缘附近存在更多材料（这尤其有益，因为边缘处的应力高于中性轴）。还发现，从所提出的表达式中获得的阻尼比与实验测量值非常吻合，最大偏差约为 10%。