基于振动测试的非线性参数识别方法

研究了利用特殊的正弦扫频技术识别非线性参数的方法。该方法利用目前线性系统成熟的模态分析技术，并结合等效线性化理论，通过振动测试识别结构的非线性参数，可以建立一个更加准确的模型来反映非线性结构的动力学特性，从而提高模型的预测精度。该方法包括两部分：（1）常位移测试识别非线性刚度；（2）常速度测试识别非线性阻尼。常位移测试是在一次正弦扫频过程中，通过调整各频率下的激励力幅值使得位移响应的幅值为常数，获得一组频响函数，通过模态分析获得等效刚度；改变位移响应的幅值进行多次测试，获得多组等效刚度；对获得的一系列恒定位移响应下的等效刚度进行曲线拟合，即可获得所有线性和非线性刚度参数。常速度测试与其类似。以三自由度非线性系统为例，进行了常位移测试和

A novel method for nonlinear parametric identification based on vibration tests

A novel method for parameter identification of structural nonlinearity is developed. This method takes advantage of the modal test and analysis, and could construct a more accurate model to represent the nonlinear behavior of the structure. The method consists of two dynamic tests: constant-amplitude displacement test and constant-amplitude velocity test. The two tests all use special sinusoidal force excitations. The constant-amplitude displacement test is used to identify nonlinear stiffness terms from measured frequency response functions of the structure subjected to sinusoidal force excitations which need to ensure the amplitudes of displacement is constant through adjusting the amplitudes of the force over the frequency range. The constant-amplitude velocity test is similar to the constant-amplitude displacement and used to identify nonlinear damping terms. A simulated 3DOF lumped-mass system with a weak nonlinear stiffness and damping behavior is used to verify the method.