基于频响函数的螺栓结合部法向刚度辨识与实验研究

Identification and Experiment Research of Bolted Joints Normal Stiffness Based on FRF

机械结合部对于高速卧式加工中心的动态性能有着重要的影响,结合部动力学参数的正确辨识是建立其准确动力学模型的前提。为准确获取螺栓接合部的法向刚度,采用理论推导与现场实验相结合的方式,基于频响函数法对结合部动力学参数的辨识与等效方法进行研究;定义了实验数据灵敏度的计算方法,并通过灵敏度实现了对实验数据的筛选,提取了有利数据和抑制了不利数据;在此基础上,构建包含辨识公式的矛盾方程,并基于最小二乘思想求得方程的确定解,获得了结合部动力学的等效参数。最后,通过LMS噪声、振动测试系统进行实验,实验结果表明:本方法可有效提高结合部动力学参数的辨识和等效精度。

Mechanical joint often has a significant effect on the dynamical behavior of high-speed horizontal machining center.Identifying the dynamic parameters of the joints correctly is a prerequisite to establish its precise dynamic model.The method based on frequency response function(FRF) to identify the characteristic parameters of bolted joints and make some researches on the equivalent way was proposed by combining theoretical derivation with experimental research,which defined identification formula and sensitivity,and the experimental data was selected by sensitivity which could extract the favorable data and suppress the unfavorable data.On this basis,the inconsistent equation containing identification formula was established,and the equivalent dynamic parameters were obtained through solving the inconsistent equation by means of the least square sense.In the end,this method was applied to one experiment based on LMS system,and the result showed that it significantly improved the identification and equivalence precision.