Investigation of modal Iwan models for structures with bolted joints
Investigation of modal Iwan models for structures with bolted joints
复制标题
螺栓连接结构的模态 Iwan 模型研究
DOI：
10.1007/978-1-4614-6540-9_2
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发表时间：
2014
期刊：
影响因子：
8
通讯作者：
D. Segalman
中科院分区：
文献类型：
--
作者：
Brandon J. Deaner;M. Allen;M. Starr;D. Segalman
具有机械接头的结构很难精确建模;即使系统的固有频率基本保持恒定，也经常观察到接头引入的阻尼与振幅呈非线性关系。尽管单个关节的模型已经取得了一些成功，但具有许多关节的结构的建模仍然是一个重大障碍。这项工作探讨了非线性阻尼是否可以应用在一个模态框架，而不是在一个结构内的每个离散关节建模，非线性阻尼模型用于每个感兴趣的模式。这种方法假设结构的模态形状不随振幅显著变化，并且模态之间的耦合可以忽略不计。非线性Iwan关节模型已成功地模拟了单个关节的非线性阻尼，并在这项工作中用作模态阻尼模型。所提出的方法首先评估通过模拟一个结构，在有限元代码中有少量的离散伊万接头（螺栓连接）。一个模态伊万模型是适合从这个结构的模拟测量和模态模型的准确性进行评估。然后，该方法被应用到实际的实验硬件具有类似的配置和模态阻尼模型被确定为系统的前几个模式。所提出的方法似乎捕捉系统的响应相当好，在这两种情况下，特别是在低力水平时，宏观滑移不发生。
Structures with mechanical joints are difficult to accurately model; even when the natural frequencies of the system remain essentially constant, the damping introduced by the joints is often observed to depend nonlinearly on amplitude. Although models for individual joints have been employed with some success, the modeling of a structure with many joints remains a significant obstacle. This work explores whether nonlinear damping can be applied in a modal framework, where instead of modeling each discrete joint within a structure, a nonlinear damping model is used for each mode of interest. This approach assumes that the mode shapes of the structure do not change significantly with amplitude and that there is negligible coupling between modes. The nonlinear Iwan joint model has had success in modeling the nonlinear damping of individual joints and is used as a modal damping model in this work. The proposed methodology is first evaluated by simulating a structure with a small number of discrete Iwan joints (bolted joints) in a finite element code. A modal Iwan model is fit to simulated measurements from this structure and the accuracy of the modal model is assessed. The methodology is then applied to actual experimental hardware with a similar configuration and a modal damping model is identified for the first few modes of the system. The proposed approach seems to capture the response of the system quite well in both cases, especially at low force levels when macro-slip does not occur.