In this research, the change of coefficient of thermal expansion(CTE) of graphite/epoxy composite laminate under space environment was measured using fiber optic sensors. Two Fiber Bragg grating(FBG) sensors have been investigated for the simultaneous measurement of thermal strain and temperature. Low earth orbit(LEO) conditions with high vacuum, ultraviolet and thermal cycling environments were simulated in a thermal vacuum chamber. In pre-test, a FBG temperature sensor was calibrated and a FBG strain sensor was verified through the comparison with the electric strain gauge(ESG) attached on an aluminum specimen in the same temperature range with the thermal cycling. The change of the CTE in composite laminate exposed to space environment was measured for intervals of aging cycles in real time.
As a whole, there was no abrupt change of the CTE after 400 aging cycles. After aging, however, the CTE decreased a little and then increased again at higher temperature region than room temperature and the CTE showed a slight increase at lower temperature region than room temperature. These changes are caused by outgassing, moisture desorbption and matrix cracking, etc.
