基于Hammerstein模型的柴油机隔振非线性系统振动分析

摘要

针对柴油机隔振非线性系统，提出基于Hammerstein模型的曲线拟合方法，研究系统非线性对其振动特性的影响，并在模态试验基础上获得线性结构动力特征。基于Hammerstein模型建立广义频响函数，考虑基频谐振广义频响函数对基频响应的作用，提取系统（1阶广义）频响函数。曲线拟合技术对（1阶广义）频响函数进行频域估计，识别出线性结构动力特征。模态参数辨识试验结果表明，提出的方法对于柴油机隔振非线性系统的线性模态参数估计是合理、有效的。基于Hammerstein模型的曲线拟合，能够消除系统非线性对振动特性影响，并能够获得系统的线性结构动力特征。%For a nonlinear diesel vibration isolation system,a curve fitting method based on Hammerstein model was proposed,it could describe for the nonlinearity to affect features of the vibration system and how to get its linear structural dynamical features by implementing modal tests.Generalized frequency response functions (GFRFs ) were established based on Hammerstein model,and the 1 st generalized FRF of the system was extracted when considering the fundamental frequency harmonic GFRF impact on the fundamental frequency response.The 1 st generalized FRF was estimated by employing the curve fitting method in frequency-domain,and the linear structural dynamical feature was identified.The experimental results of modal parameters identification showed that the proposed method is valid and feasible to estimate the linear modal parameters of the nonlinear diesel vibration isolation system;using the curve fitting based on Hammerstein model,one can eliminate the nonlinearity effects on the features of the vibration system,and can obtain the linear structural dynamical features of the nonlinear system.