【作者】 苏向荣；

【导师】 丁康；

【作者基本信息】 汕头大学 ， 机械电子工程， 2003， 硕士

【摘要】 针对信号有随机噪声影响时，利用现有的四种离散频谱校正方法校正出的频率、幅值和相位精度都会降低的问题，从理论上推导出通用相位差法校正后的频率、幅值和相位在随机噪声影响下的方差值，以研究噪声如何影响这些参数的精度，并编制了相应的实用程序进行实际计算。 提出了一种精确计算结构小阻尼的新方法。该方法的原理是对自由衰减振动信号采一段连续样本，从样本的起始点和隔L点为新起始点分别进行两次同样点数的傅里叶变换，利用对应谱峰处的幅值计算出阻尼。从理论上分析，不考虑模态裙部的影响，这是一种精确计算小阻尼的方法，计算阻尼不随采样频率的变化而变化，不受时域截断产生的能量泄漏的影响，能应用于多自由度系统阻尼的求解。更多还原

【Abstract】 The study is based on the project of National Natural Science Fund of China, the State Ministry of Education of China and State Key Laboratory of Vibration, Shock and Noise, which deeply research on spectrum correcting technology in dynamic signal analysis.When a signal contaminated by additive noise, the accuracy of the estimation of the parameters, i.e., amplitude, frequency and phase corrected by now existing four spectrum correcting methods will drop. This paper quantitatively investigates the noise influence on the accuracy of the universal-phase-difference-based method.This thesis also presents a new method for estimating the damping of a structure. The basic principle of this method is that sampling a length of continuous freedom transient responses signal, and performing FFT(Fast Fourier Transform) from the starting point, then shifting the starting point with L points and performing FFT again, finally estimating the damping by making use of the amplitudes of two corresponding peak lines. If not considering the model coupling, the method is a precise solution, and the estimating damping will not change with spectral leakage. The simulation results and engineering testing show that the estimated damping has high precise. The method can also apply to the Multi-DOF system.更多还原