材料期刊网

研究了一种新型的自参考型光纤固化传感器,用于环氧树脂固化过程的实时监测.用光纤芯折射率为1.558的多模光纤制成端面反射型折射率传感器,利用环氧树脂的折射率与固化度之间的对应关系,通过实时测量环氧树脂的折射率进行固化监测.在固化过程中,当环氧树脂的折射率变化到与光纤芯的折射率相等时,传感界面的反射信号为零,传感器可对零点偏置和灵敏系数进行校准,在此后的固化过程中,传感器能够定量地测量环氧树脂的固化度.在用多个传感器对树脂内不同部位的固化过程同时进行监测的场合,各传感器经实时自参考校准后,可根据各自的灵敏系数对输出信号统一定标,从而可以相互比较,实时地反映不同部位的固化反应过程之间的差异.

A self-referenced optical fiber cure sensor is proposed to in-situ monitor the cure of epoxy resins. The sensor is fabricated by cleaving a multimode step index optical fiber whose core is of refractive index 1.558, the cleaved end is used to infer the refractive index of the epoxy during cure. The refractive index of the fiber core serves as a reference to calibrate the zero bias and sensitivity of the sensor. As the refractive index of the epoxy system increases with the extent of cure, it will equal the refractive index of the fiber core at a cure extent and then the calibration can be done. Thus, in the later parts of the cure, the sensor can provide quantitative information about cure reaction. When monitoring the cure of composites, the sensors embedded in different part of the structure can be normalized to a common scale such that the real-time comparison of each sensor's output becomes possible. The validity and feasibility of the proposed sensor have been confirmed in the cure monitoring experiments on an epoxy system.