VIBROACOUSTIC DIAGNOSTICS OF OPEN-TYPE (UN-PRESSURIZED) SPACECRAFTS

A special feature of the open design spacecraft is the presence of a CFRP (carbon-fiber reinforced plastic) cylinder around which three-layered honeycomb panels are fixed by means of pylons. The electronic equipment, antenna and feeder relay systems, units and instruments of the satellite control system are installed on these panels. Vibration loading of such structures is proposed to carry out both with the help of an electrodynamic shaker (up to 100 Hz) and a diffuse sound field in the reverberation chamber. The structure response to acoustic and vibration loading is fixed by accelerometers and presented in the form of amplitude-frequency characteristics and the power spectral density function of the random signal from the vibration frequency. The spacecraft defects are determined by parametric variations of its vibration response. To do this, vibration and acoustic tests are carried out in three stages. At the first stage the probing vibration loading the structure with low intensity is performed. Test results - resonant frequencies and vibration amplitudes – are compared with the design values or the values defined at the ground experimental development of the spacecraft. At the second stage the tests are performed at high loads, but in safe modes, calculated by a special technique. The third stage is a repetition of the first one. As a result, the defect location and nature are determined by the vibration parameters deviations. The article presents the methodology main statements and the spacecrafts vibroacoustic diagnostics results. It is concluded that the use of such diagnostics in the final stages of products manufacturing is reasonable.