Micro-satellite structure fracture investigation techniques

Mounting accuracy of satellite payload and ADCS (attitude determination and control subsystem) seats is one of the requirements to achieve the satellite mission with satisfactory performance. Deviation of the position of the mounting seat for multi-band-earth-imager (MBEI) is caused by cracks in the plate of the basis unit and bracket for attachment of MBEI. These cracks were detected during inspection of the satellite strength mock-up after vibration testing for air transportation phase. Most probable reason of the cracking is fatigue damage as strength mock-up structure was subjected to prolonged vibration loading during various loading cases. Total vibration duration during testing is about 56 hours. In order to study the cracking reasons, finite element modeling of the structural parts of the basis unit including MBEI bracket and instrument MBEI is subjected to harmonic response to simulate vibration loading for the case of air transportation. Numerical results are compared with the experimental ones, and mechanical design of the basis-plate unit is modified.