Abstract Dynamically large structures can have many closely spaced modes. A particular example is an extruded aluminium panel used for building high-speed trains. Such a structure may be modelled deterministically with a large number of degrees of freedom (dofs), or statistically represented as a statistical energy analysis (SEA) system having particular SEA parameters. In both cases, experimental modal parameter identification may be required. Although there are several commercial packages which can be used for modal parameter identification, alternative methods with different strengths and/or convenience are still desirable. In this paper, the double-exponential windowing method developed by the second author is revisited and improved. Improvements are achieved by taking into account the effect of the finite time duration of Fourier transforms and making use of the real parts of driving point mobilities. The method is easy to implement and the improvements make the choice of the decay rate in the exponential window much flexible: for a very lightly damped structure, it allows to use a large positive decay rate to depress measurement noise, and for a highly damped structure, it allows to use a negative decay rate to make modes more evident or to separate overlapped modes. The usefulness of the improved method are demonstrated for a 30-bladed wheel model with known modal parameters, and for an extruded aluminium panel.

中文翻译：

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改进双指数加窗法识别动态大型结构的模态频率和阻尼比

摘要 动态大结构可以有许多紧密间隔的模式。一个特殊的例子是用于建造高速列车的挤压铝板。这种结构可以用大量的自由度 (dof) 确定性地建模，或者统计地表示为具有特定 SEA 参数的统计能量分析 (SEA) 系统。在这两种情况下，可能需要实验模态参数识别。尽管有几个商业包可用于模态参数识别，但仍然需要具有不同强度和/或便利性的替代方法。本文对第二作者开发的双指数加窗方法进行了重新审视和改进。通过考虑傅立叶变换的有限持续时间的影响并利用驱动点迁移率的实部来实现改进。该方法易于实施并且改进使得指数窗口中衰减率的选择更加灵活：对于非常轻的阻尼结构，它允许使用大的正衰减率来抑制测量噪声，对于高阻尼结构，它允许使用大的正衰减率，它允许使用负衰减率使模式更明显或分离重叠模式。改进方法的有效性在具有已知模态参数的 30 叶轮模型和挤压铝板中得到了证明。该方法易于实施并且改进使得指数窗口中衰减率的选择更加灵活：对于非常轻的阻尼结构，它允许使用大的正衰减率来抑制测量噪声，对于高阻尼结构，它允许使用大的正衰减率，它允许使用负衰减率使模式更明显或分离重叠模式。改进方法的有效性在具有已知模态参数的 30 叶轮模型和挤压铝板中得到了证明。该方法易于实施并且改进使得指数窗口中衰减率的选择更加灵活：对于非常轻的阻尼结构，它允许使用大的正衰减率来抑制测量噪声，对于高阻尼结构，它允许使用大的正衰减率，它允许使用负衰减率使模式更明显或分离重叠模式。改进方法的有效性在具有已知模态参数的 30 叶轮模型和挤压铝板中得到了证明。