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本文介绍实验测定航天飞机主推进试验样件固有振型用的单点激振方法,这项测试是在国家空间技术实验室的静态点火试验台上进行的。文中还介绍了试验技术、设备和有关的软件。最后将试验结果与数学模型的结果作了比较。分别利用三台单点液压激振器给支承主发动机的主推进系统试验样件的推力架施加随机激振力。利用微计算机试验设备处理所产生的加速度和力信号来测定50赫以下的共振频率、振型形状和阻尼值。试验了两种构型:一个带有空的液氢和液氧贮箱;另一个带有装了40％液氧的贮箱和输送管路。试验结果是在主推进试验时间最少和化费最小的情况下取得的。
This paper presents a single-point excitation method for experimentally determining the natural modes of the main propulsion sample of a space shuttle. This test was conducted on the static ignition test rig of the National Space Technology Laboratory. The article also describes the test technology, equipment and related software. Finally, the experimental results are compared with the results of the mathematical model. Three single-point hydraulic exciters are respectively used to impose random exciting force on the thrust frame of the main propulsion system test sample supporting the main engine. Using the microcomputer test equipment to deal with the resulting acceleration and force signals to determine the resonance frequency below 50 Hz, mode shape and damping values. Two configurations were tested: one with empty liquid hydrogen and liquid oxygen tanks and the other with a tank and transfer line filled with 40% liquid oxygen. The test result is obtained with the least time for the main propulsion test and the minimum cost.