火箭推进

为了获得准确的液体火箭发动机机架的结构动力学模型,采用精细化的结构动力学建模方法,建立了可以同时反映机架静力和动力学特性的详细有限元模型,并以两种状态下实测数据对机架模型进行了进一步修正。开展了固支状态下的静力试验,获得了机架上关键测点的位移响应; 开展了自由状态下的模态试验,获得了自由状态下机架的固有频率和振型; 最后以静力试验的位移数据和模态试验的固有频率数据为目标函数,对机架各部分材料的弹性模量中关于位移和频率最灵敏的6个参数进行了修正。结果表明:修正后的机架模型不仅在修正采用的频率范围内与实测值吻合得很好,而且在修正采用的频率范围外理论和试验结果的相关性也有较大提高。模型修正中联合静态响应数据和动力学数据是可行的,静力学试验结果可以提供模态试验中得不到的信息,有利于模型修正过程。

In order to obtain an accurate structural dynamic model of thrust frame in liquid rocket engine,a detailed structural dynamics modeling approach was adopted to establish a detailed finite element(FE)model that can simultaneously describe the static and dynamic characteristics of the frame.The established model was further updated according to two different types of test data. The static test under the fixed support state was carried out,and the displacement response of the key measuring points on the frame was obtained. The modal test under the free state was carried out,and the natural frequency and mode shape under this state were identified. Finally,using the obtained displacement data and the natural frequencies as the objective function,the six most sensitive parameters to displacement and frequency in the elastic modulus of frame materials were updated. The results show that the updated frame model agrees well with the measured values not only within the frequency range used in the correlation,but also beyond the frequency range used in the correlation. It is feasible to combine static response data and modal test data in the model updating. The static test results can provide the information that is not available in the modal test,which is beneficial to the model updating process.

引言
1 静力试验
2 模态试验
3 模型修正过程
4 结论

图1 静力试验力载荷和位移测点<br/>Fig.1 Force load and displacement measurement points in static test

图1 静力试验力载荷和位移测点
Fig.1 Force load and displacement measurement points in static test

表1 静力试验中各个测点的位移<br/>Tab.1 Displacement of each measurement point in static test

表1 静力试验中各个测点的位移
Tab.1 Displacement of each measurement point in static test

图2 模态试验照片
Fig.2 Modal test photo

图3 试验测点模型
Fig.3 Measurement model

图4 试验振型的Auto-MAC矩阵<br/>Fig.4 Auto-MAC matrix of experimental mode shape

图4 试验振型的Auto-MAC矩阵
Fig.4 Auto-MAC matrix of experimental mode shape

图5 自由状态下机架实测振型<br/>Fig.5 Experimental mode shape of thrust frame under free-free conditions

图5 自由状态下机架实测振型
Fig.5 Experimental mode shape of thrust frame under free-free conditions

图6 机架初始有限元模型<br/>Fig.6 Initial FE model of thrust frame

图6 机架初始有限元模型
Fig.6 Initial FE model of thrust frame

图7 同一坐标系下机架的试验模型及有限元模型<br/>Fig.7 Experimental model and FE model of thrust frame under the same coordinate system

图7 同一坐标系下机架的试验模型及有限元模型
Fig.7 Experimental model and FE model of thrust frame under the same coordinate system

图8 初始模型理论和实测振型的MAC矩阵<br/>Fig.8 MAC matrix of initial FE model mode shape versus experimental mode shape

图8 初始模型理论和实测振型的MAC矩阵
Fig.8 MAC matrix of initial FE model mode shape versus experimental mode shape

图9 静力载荷下机架位移云图<br/>Fig.9 Displacement nephogram of thrust frame under static load

图9 静力载荷下机架位移云图
Fig.9 Displacement nephogram of thrust frame under static load

表2 初始模型理论与实测位移比较<br/>Tab.2 Comparison of initial FE displacement and measured displacement

表2 初始模型理论与实测位移比较
Tab.2 Comparison of initial FE displacement and measured displacement

图10 5#～9#测点z向位移对32个弹性模量的灵敏度<br/>Fig.10 Sensitivity of 5#～9# z direction displacement to 32 elasticity moduli

图10 5#～9#测点z向位移对32个弹性模量的灵敏度
Fig.10 Sensitivity of 5#～9# z direction displacement to 32 elasticity moduli

图11 固有频率对32个弹性模量的灵敏度<br/>Fig.11 Sensitivity of natural frequency to 32 elasticity moduli

图11 固有频率对32个弹性模量的灵敏度
Fig.11 Sensitivity of natural frequency to 32 elasticity moduli

图12 6个待修正参数位置<br/>Fig.12 Positions of 6 parameters to be updated

图12 6个待修正参数位置
Fig.12 Positions of 6 parameters to be updated

图13 模型修正迭代过程<br/>Fig.13 Iteration process of model updating

图13 模型修正迭代过程
Fig.13 Iteration process of model updating

图14 模型修正后理论与试验振型MAC矩阵<br/>Fig.14 MAC matrix of tuned FE model mode shape versus experimental mode shape

图14 模型修正后理论与试验振型MAC矩阵
Fig.14 MAC matrix of tuned FE model mode shape versus experimental mode shape

表3 修正前后理论与试验结果比较<br/>Tab.3 Comparison of untuned and tuned model's results versus test results

表3 修正前后理论与试验结果比较
Tab.3 Comparison of untuned and tuned model's results versus test results

图15 修正前后理论振型与实测61 Hz振型比较<br/>Fig.15 Comparison of untuned and tuned FE's mode shape verus experimental mode shape at 61 Hz

图15 修正前后理论振型与实测61 Hz振型比较
Fig.15 Comparison of untuned and tuned FE's mode shape verus experimental mode shape at 61 Hz

图16 修正后机架理论振型<br/>Fig.16 Analytical mode shape of tuned model

图16 修正后机架理论振型
Fig.16 Analytical mode shape of tuned model

表4 模型修正前后理论与实测位移对比<br/>Tab.4 Comparison of untuned and tuned FE's displacement verus experimental displacement

表4 模型修正前后理论与实测位移对比
Tab.4 Comparison of untuned and tuned FE's displacement verus experimental displacement

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备注

引言

1 静力试验

2 模态试验

3 模型修正过程

4 结论

期刊信息