Sensing damage in carbon fiber polymer-matrix composites during fatigue by electrical resistance measurement

Xiaojun Wang; Deborah D. L. Chung

doi:10.1117/12.317004

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21 July 1998 Sensing damage in carbon fiber polymer-matrix composites during fatigue by electrical resistance measurement

Xiaojun Wang, Deborah D. L. Chung

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Proceedings Volume 3330, Smart Structures and Materials 1998: Sensory Phenomena and Measurement Instrumentation for Smart Structures and Materials; (1998) https://doi.org/10.1117/12.317004
Event: 5th Annual International Symposium on Smart Structures and Materials, 1998, San Diego, CA, United States

Abstract

Self-monitoring of static/fatigue damage and dynamic strain in a continuous crossply carbon fiber polymer-matrix composite by electrical resistance (R) measurement was achieved. With a static/cyclic tensile stress along the 0 degree direction, R in this direction and R perpendicular to the fiber layers were measured.Upon static tension to failure, R in the 0 direction first decreased and then increased, while R perpendicular to the fiber layers increased monotonically. Upon cyclic tension, R decreased reversibly, while R perpendicular to the fiber layers increased reversibly, though R in both directions changed irreversibly by a small amount after the first cycle. Upon fatigue testing at a maximum stress of 57 percent of the fracture stress, R irreversibly increased both in spurts and continuously, due to 0 degree fiber breakage, which started at 15 percent of the fatigue life, while R irreversibly increased both in spurts and continuously, due to delamination, which started at 33 percent of the fatigue life. The peak R in a cycle irreversibly decreased, while the minimum R at the end of a cycle irreversibly increased during the first 0.1 percent of the fatigue life, due to irreversible increases in the degree of 0 fiber alignment. R became noisy starting at 87 percent of the fatigue life, whereas R became noisy starting at 50 percent of the fatigue life. For a unidirectional composite, R increased reversibly upon tension and decreased reversibly upon compression in the 0 direction, due to piezoresistivity.

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Xiaojun Wang and Deborah D. L. Chung "Sensing damage in carbon fiber polymer-matrix composites during fatigue by electrical resistance measurement", Proc. SPIE 3330, Smart Structures and Materials 1998: Sensory Phenomena and Measurement Instrumentation for Smart Structures and Materials, (21 July 1998); https://doi.org/10.1117/12.317004

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