基于径向切比雪夫矩函数的结构动力学模型修正

Model updating in structural dynamics based on radial-Tchebichef moments

提出基于径向切比雪夫矩函数的振型描述及模型修正的方法,并应用于实际结构.将结构的模态振型用径向切比雪夫矩特征值表示,可以用很少的数据很好地描述振型数据的特征,实现振型数据的压缩.将径向切比雪夫矩特征值用于相关分析中,克服了利用模态置信准则描述对称结构重模态的缺陷.进一步将径向切比雪夫矩特征值用于模型修正中,克服了将振型数据直接用于修正中会产生的一些问题,如振型数据量过大、修正不易收敛等.以某航空发动机实验器的封油盖为例,进行振动模态测试实验,利用径向切比雪夫矩函数对其进行相关分析及模型修正,修正前后,封油盖有限元的前13阶固有频率的预测值与实际结构模态测试的实验值误差由最大值17.13%降低到1.23%,验证了该方法的有效性.

Vibration mode shape description and model updating method based on radialTchebichef moments was proposed and applied to an actual structure.Radial-Tchebichef moments descriptors were extracted from vibration mode data to describe the most important information of the vibration mode data,realizing the process of data compression.Using radial-Tchebichef moments descriptors in correlation analysis,it overcame the difficulty of double mode when the modal assurance criterion was used to describe the symmetrical structure.It also avoided the problems when vibration mode data was used directly in the process of model updating such as large amount of data and misconvergence of updating parameter.Taking the cover of an aero-engine test rig as an example,the virbation modal test was carried out and radial-Tchebichef moments were used in correlation analysis and model updating.The result shows that the frequency deviation between the test and finite element mod-el is reduced from 17.13%to 1.23%after model updating in the first 13 modes and this case verifies the effectiveness of the proposed method.