Abstract: Fatigue behavior of graphite/epoxy laminate, having $LB@0/$POM@45/90$RB$-s$/ lay-up and embedded with piezoelectric (lead zirconate-titanate, PZT) actuator, was investigated under combined mechanical and electrical cycling loading condition. The PZT was inserted into a cutout area in the two middle 90-degrees plies. Experiments involved cycling of specimens at various maximum stress levels along with the excitation of the embedded actuator from $MIN@10 V to $MIN@100 V or 10 V to 100 V, which resulted in either in-phase or out-of-phase electrically induced strain relative to the applied mechanical loading or strain. In general, PZT performed better in the out-of phase than in the in-phase electromechanical fatigue condition. The fatigue life of the embedded PZT was more than one million cycles, for the applied maximum stress levels well above its design limit in the out-of-phase electromechanical and in only mechanical fatigue conditions. The PZT failed before one million cycles during the in-phase test at the applied maximum stress equal to its design limit. Above this stress level, a sharp drop-off occurred in the fatigue life during the in-phase electromechanical cycling condition.!8
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