基于优化STD法的大飞机垂尾装配界面精加工过程模态参数识别

为减小大飞机垂尾装配界面精加工过程中产生的加工振动对其精加工质量的影响，需掌握装配界面加工过程的动力学特性，而动力学特性与其模态参数密切相关。因此，为获得装配界面各阶模态参数，针对其动态精加工过程，提出了一种优化STD环境激励下结构模态参数识别方法。该方法首先由装配界面的实测加工振动数据构造Toeplitz矩阵，并将其作为STD法的输入，进而求出装配界面各阶次模态参数，并构成模态参数下三角矩阵。然后利用模态置信因子及模态保证准则选出阶次相对稳定的模态参数作为装配界面的真实模态参数。最后，通过切削实验和锤击测试验证优化STD法的正确性和有效性。将锤击实验模态结果作为装配界面的模态参数测量参考值，以一阶模态频率识别结果为例，该方法相比于传统STD法和SSI法，识别精度分别提高了12.71%和3.82%；同理其余各阶模态参数识别精度均有不同程度的提高。通过优化STD法可准确高效地获得装配界面的模态参数，为其精加工工艺参数的合理选择提供了理论依据和技术支持。

Modal parameter identification of finishing assembly interface of vertical tail section of large aircraft based on optimized STD method

To reduce the impact of machining vibration on the machining quality of the assembly interface of large aircraft in finishing, it is necessary to understand the dynamic characteristics and the modal parameters of the assembly interface. Hence, an optimized Space Time Domain (STD) method is proposed to identify the modal parameters during the dynamic finish machining. Firstly, a Toeplitz matrix is generated by the measured machining vibration data of the assembly interface and is treated as the input of the STD method. Secondly, the relative stable modal parameters are selected as the modal parameters of the assembly interface in terms of the modal confidence factor and the Modal Assurance Criterion (MAC). Finally, the correctness and effectiveness of the optimized STD method are validated through impact tests and cutting experiments. In detail, the results of the impact test are regarded as the referenced modal parameters of the assembly interface. Taking the 1st-order modal identification result as an example, the modal identification accuracy of the optimized STD method is improved by 12.7% and 3.82% compared with the traditional STD and SSI methods. The identification accuracy of the modal parameters of the rest orders can also be improved to a certain extent as well. Therefore, the modal parameters of the assembly interface can be accurately and efficiently identified via the optimized STD method, which can theoretically and technically support the reasonable selection of the finish machining parameters.