星箭连接界面载荷识别与控制研究

发布时间：2018-02-04 16:21

本文关键词： 航天器过试验力限控制载荷识别应变检测有限元仿真试验验证　出处：《南京航空航天大学》2016年硕士论文　论文类型：学位论文

【摘要】：航天器舱段连接界面、航天器与运载对接界面的载荷特性是航天器结构设计的重要依据,航天器在地面振动试验时容易产生“过试验”现象,力限控制技术是解决“过试验”问题的主要手段。这些都对星箭界面载荷的识别方法研究提出了迫切的需求。本文解析推导出一种基于星箭连接环的应变变化场的界面载荷识别方法,并通过有限元仿真和工装试验对其进行校验。主要研究工作和结果如下:(1)根据薄板假设对载荷识别方法进行推导。由于星箭连接环直径远远大于厚度,所以将其离散为一个个微元,每个微元都可以假设为一个薄板,根据弹性力学中的薄板假设,径向应力应变为零。然后在连接环外围布置一圈应变检测点,由卫星受载时连接环的应变变化场推导得到六自由度载荷。由于工程实际中,无法得到连续的应变变化场,所以将公式离散化,得到离散的载荷识别方程。(2)通过有限元仿真对该载荷识别方法进行有效性验证。仿真结果显示,六自由度载荷静态识别误差均不超过7%,动态误差不超过10%。且虽然航天器受载时,隔板对于连接环相当于施加一个集中力的影响,但不影响载荷识别的精度,说明该载荷识别方法可以有效避免隔板、底板、连接环特殊结构对载荷识别精度的影响。考虑工程实际问题,提出减少应变检测点的优化方案,结果显示静态载荷识别误差在12%以下,动态载荷识别误差均在20%以下。最后进行针对个别检测点损坏的敏感度分析。(3)通过构建的星箭界面载荷识别系统对该载荷识别方法进行试验验证。静态试验结果显示,只有个别载荷的识别误差为20%,其他载荷识别误差均在10%以内。且当施加载荷越大时,载荷识别误差越小,原因是当施加较小载荷时,个别应变检测点处应变变化很小,由于应变片本身存在漂移现象,导致检测到的应变数据存在误差。当施加较大载荷时,应变片漂移现象导致的误差相应减小,检测误差变小。将动态试验结果由时域转换至频域,结果显示,该载荷识别方法可以有效的检测到峰值所对应的频率及幅值大小,大部分幅值误差均在10%以内。
[Abstract]:The load characteristic of the interface between spacecraft and vehicle is an important basis for the design of spacecraft structure, and the phenomenon of "overtest" is easy to occur in the ground vibration test of spacecraft. Force limit Control Technology is to solve the problem of "overtest" The main means of the problem. All these put forward an urgent need for the research of the identification method of the interfacial load of the star-arrow. In this paper, an interfacial load identification method based on the strain variation field of the star-arrow connection ring is derived. The main research work and results are as follows: 1) deducing the load identification method according to the thin plate hypothesis. Because the diameter of the star-arrow connection ring is much larger than the thickness. So it can be discretized into microelements, each of which can be assumed as a thin plate. According to the assumption of thin plate in elastic mechanics, the radial stress-strain is zero. Then a circle of strain detection points are arranged around the connecting ring. The six-degree-of-freedom load is derived from the strain variation field of the connecting ring when the satellite is loaded, and the formula is discretized because the continuous strain variation field can not be obtained in engineering practice. The discrete load identification equation is obtained. (2) the validity of the method is verified by finite element simulation. The simulation results show that the static identification error of the six-degree-of-freedom load is less than 7%. The dynamic error is not more than 10. And although the spacer exerts the effect of a concentration force on the connecting ring when the spacecraft is loaded, it does not affect the accuracy of load identification. It is shown that the load identification method can effectively avoid the influence of the special structure of diaphragm, bottom plate and connecting ring on the accuracy of load identification. Considering the practical problems of engineering, the optimization scheme of reducing strain detection points is put forward. The results show that the error of static load identification is less than 12%. The error of dynamic load identification is below 20%. Finally, sensitivity analysis for damage of individual detection points is carried out. The static test results show that the method is verified by the load identification system of star-arrow interface. Only the identification error of individual load is 20 and the other load identification error is less than 10%. And the larger the load is, the smaller the load identification error is, the reason is that the smaller load is applied. The strain variation at individual strain detection points is very small, because of the drift phenomenon of strain gauge itself, which leads to the error of the detected strain data, and the error caused by strain gauge drift phenomenon decreases correspondingly when a large load is applied. The dynamic test results are converted from time domain to frequency domain. The results show that the load identification method can effectively detect the frequency and amplitude corresponding to the peak value. Most of the amplitude errors are within 10%.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：V414;V423

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