Real-time monitoring of fatigue damage and dynamic strain in a continuous unidirectional carbon fiber polymer-matrix composite by longitudinal electrical resistance measurement was achieved. The resistance R decreased reversibly upon tensile loading in every cycle, thus providing dynamic strain monitoring. The peak R in a cycle irreversibly increased as fatigue damage occurred, due to fiber breakage. At 55% of the fatigue life, the peak R started to increase in spurts. At 89% of the fatigue life, the peak R started to increase continuously from cycle to cycle, but gradually. At 99.9% of the fatigue life, the peak R started to increase rapidly, both continuously and in spurts. The last spurt occurred at 99.997% of the fatigue life.
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