自然激励下的运载火箭时变模态参数获取技术研究

Time-Varying Modal Acquisition Technology of Large-Scale Structure under Natural Excitation

新一代运载火箭在靶场加满液氢和液氧推进剂后,由于安全因素无法开展传统的有源激励模态试验,为了提高发射稳定性,必须获取运载火箭全状态下的模态参数。基于结构振动响应的互相关函数与单位脉冲函数具有相同数学构架的前提,采用改进模态自然激励技术(NExT-LSCE-LSFD)对风激励下采集的时域数据进行识别,获得了火箭加注过程中的时变模态参数,并通过空箱和液氧加注状态的力锤激励模态试验结果验证了自然激励方法的有效性。本次研究发展了自然风激励下的大型结构时变模态获取技术,可推广到其他大型结构工作模态在线识别技术研究。

After the new generation launch vehicle is filled with liquid hydrogen and liquid oxygen propellant in the launch site,the traditional modal test method cannot be carried out due to safety factors.In order to improve the launch stability,it is necessary to obtain the modal parameters of the launch vehicle with full propellant.Based on the premise that the cross-correlation function and the unit impulse function of the structural vibration response have the same mathematical framework,the time-varying modal parameters of the launch vehicle during the propellant filling process are obtained by using the improved modal natural excitation technique.The effectiveness of the natural excitation method is verified by the traditional modal test results of the full liquid oxygen,this research develops the time-varying modal acquisition technology of large-scale structure under natural wind excitation,which can be extended to the field of on-line flight modal identification and health monitoring in the future.