A Structural Dynamics Parameter Identification Method Based on the Modal Space Time-Domain Precise Integration
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摘要: 提出了一种基于模态空间时域精细积分的动力学参数辨识方法. 首先,基于时域测量信号和理论预测模型构造辨识方程,在模态空间内,由时域精细积分方法构造了理论预测模型;其次,通过矩阵、向量的Kronecker积运算法则推导了辨识模态的无约束向量的二次型函数,解析地给出了辨识振型的数学表达;最后,通过对辨识优化问题进行数学变换,仅需要辨识结构动力学特性的谱参数(频率和阻尼比),极大地降低了辨识参数的维度. 数值算例中,进行了三自由度弹簧质量系统和高速受电弓的动力学参数辨识,辨识得到的固有频率、阻尼比与理论值相比,误差在8%以内;辨识振型与理论振型之间的夹角的余弦接近1,验证了辨识结果的准确性. 该文提出的方法能够有效地实现辨识谱参数(频率、阻尼)和空间参数(振型)的分离,具有非常好的求解效率和应用前景.Abstract: Based on the modal space time-domain precise integration, a dynamic parameter identification method was proposed. Firstly, an identification model was constructed based on the time-domain measurement signals and the theoretical prediction model with the time-domain precise integration method in the modal space. Secondly, the quadratic function of the unconstrained vector was derived through the Kronecker product of matrices, and the mathematical expressions of the mode shapes were analyzed and given. Finally, through mathematical transformations of the identification optimization problem, only the dynamics spectrum parameters (frequencies and damping ratios) need be identified, to greatly reduce the dimensionality of the identification parameters. In numerical examples, the dynamic parameter identification for the spring-mass system and the high-speed pantograph system were studied. The identified natural frequencies and damping ratios have errors less than 8% compared to the theoretical values. The cosine of the angle between the identified and the theoretical mode shapes is close to 1, which verifies the accuracy of the identification results. The proposed method can effectively achieve the separation of dynamic spectral parameters (frequencies, damping ratios) and spatial parameters (modal shapes), and has better solving efficiency and application prospects.
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Key words:
- dynamic parameter identification /
- time-domain precise integration method /
- least squares method /
- free vibration characteristic /
- dynamics optimization
edited-byedited-by1) (我刊编委赵岩来稿) -
表 1 弹簧-质量系统动力学参数辨识结果
Table 1. Identification results of dynamic parameters of the spring-mass system
parameter mode 1 mode 2 mode 3 f/Hz identification 3.854 6.236 7.339 theory 3.854 6.238 7.340 ζ/% identification 1.00 1.02 1.03 theory 1.00 1.00 1.00 γ identification 1.65 0.54 0.75 theory 1.65 0.50 0.70 CMAC 1.000 0 0.999 7 0.999 0 表 2 不同测量噪声水平谱参数辨识结果
Table 2. Dynamic spectral parameter identification results under different measurement noise levels
measurement noise
level /%mode 1 mode 2 mode 3 f/Hz ζ/% f/Hz ζ/% f/Hz ζ/% 5 3.854 1.00 6.238 1.01 7.340 1.01 10 3.854 1.00 6.237 1.02 7.340 1.02 15 3.854 1.00 6.236 1.02 7.339 1.03 20 3.854 1.01 6.236 1.03 7.339 1.05 表 3 谱参数与空间参数耦合和解耦时结果对比
Table 3. Comparison of results of spectral parameters coupled and decoupled with spatial parameters
mode 1 mode 2 mode 3 optimisation time /s f/Hz ζ/% γ f/Hz ζ/% γ f/Hz ζ/% γ decoupled 3.854 1.00 1.65 6.237 1.02 0.52 7.340 1.02 0.73 22.40 coupled 3.854 1.00 1.65 6.237 1.02 0.52 7.340 1.02 0.73 121.84 表 4 高速受电弓动力学参数辨识结果
Table 4. Identification results of dynamic parameters of the high-speed pantograph
parameter mode 1 mode 2 mode 3 mode 4 mode 5 mode 6 f/Hz identification 9.029 12.459 13.753 50.450 52.220 121.552 theory 9.035 12.472 13.764 50.585 52.376 123.320 ζ/% identification 1.23 1.08 1.05 1.10 0.90 1.10 theory 1.00 1.00 1.00 1.00 1.00 1.00 γ/10-4 identification 2.33 1.71 2.35 3.87 1.28 6.43 CMAC 0.997 4 0.998 1 0.999 6 0.999 9 0.995 5 0.999 7 表 5 高速受电弓模态试验动力学参数辨识结果
Table 5. Identification results of dynamic parameters of the high-speed pantograph modal test
parameter mode 1 mode 2 mode 3 mode 4 mode 5 proposed methodology f/Hz 10.2 12.50 48.8 133.6 219.4 ζ/% 0.46 0.36 3.95 2.711 1.84 ref. [17] f/Hz 10.0 12.50 48.4 128.5 213.0 -
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