阻尼不相似动响应模型的一种频域修正方法

An Updating Method of the Frequency Response Function for Dynamic Similitude Models with Dissimilar Damping

在动响应相似缩比模型设计和试验中,阻尼往往难以保证相似,使得模型动响应难以直接换算到结构原型上,为此提出一种基于传递函数的频域修正方法。基于稀疏模态假设,在特定模态频率的邻近频带内,仅考虑该阶模态对传递函数贡献,建立理想模型与实际模型传递函数之间的简化理论关系。以二自由度离散振动系统和实际结构振动模态试验为例,对所提出的修正方法进行了验证。结果表明,修正后的传递函数幅频曲线与目标值吻合度较好,表明了本方法的可行性和有效性。

During dynamic similitude model tests, it is generally difficult to assure the same damping of the scaled model with its original structure. As a result, the measured dynamic response of the scaled model with damping errors cannot be used directly to predict the response of the structure prototype. An updating method of the frequency response function for dynamic similitude mode^s with dissimilar damping was proposed to solve the problem. It was assumed that the modal response was sparse and only one single mode contributed to transfer function during its adjacent frequency range. An updating coefficient was established in order to connect the transfer functions between ideal model and actual model. This updating method was used to update the double-freedom-degree vibration scatter system and two aluminum board test articles. The updating results show that the updated transfer functions are consistent with the ideal mode~, which verifies the feasibility and validity of the proposed updating method.