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Proceedings Paper

Monitoring of fabrication strain and temperature during composite cure using fiber optic sensor
Author(s): Hyun-Kyu Kang; Dong-Hoon Kang; Chang-Sun Hong; Chun-Gon Kim
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Paper Abstract

Fabrication strains during cure can lead to warpage or spring-back, which presents difficulties in the assembly of composite structures and residual stresses due to differences of thermal expansion coefficients between fiber and matrix in cooling stage can have intense effects on the mechanical properties of the composite product. The quality of the final composite part is directly affected by cure time, temperature, and pressure. The knowledge of cure process is very helpful to obtain high quality composites at reduced producing cost. Therefore, sensors capable of monitoring the cure process are desired and fiber optic sensors are the good candidate for cure monitoring of composite materials. In this paper, we present the simultaneous monitoring of the fabrication strain and temperature during the composite cure process by using fiber optic sensors. Fiber Bragg grating/extrinsic Fabry-Perot interferometric (FBG/EFPI) hybrid sensors are used to monitor those measurands. The characteristic matrix of the sensor is analytically derived and measurements can be done without sensor calibration for each experiment. A wavelength-swept fiber laser is utilized as a light source. FBG/EFPI sensors are embedded in graphite/epoxy composite laminates at different direction and different location. We perform the real time monitoring of fabrication strains and temperatures at two points of composite laminates during cure process in an autoclave. Through this experiment, we can provide a basis for the efficient smart processing of composites.

Paper Details

Date Published: 3 August 2001
PDF: 8 pages
Proc. SPIE 4336, Nondestructive Evaluation of Materials and Composites V, (3 August 2001); doi: 10.1117/12.435569
Show Author Affiliations
Hyun-Kyu Kang, Korea Advanced Institute of Science and Technology (South Korea)
Dong-Hoon Kang, Korea Advanced Institute of Science and Technology (South Korea)
Chang-Sun Hong, Korea Advanced Institute of Science and Technology (South Korea)
Chun-Gon Kim, Korea Advanced Institute of Science and Technology (South Korea)


Published in SPIE Proceedings Vol. 4336:
Nondestructive Evaluation of Materials and Composites V
George Y. Baaklini; Eric S. Boltz; Steven M. Shepard; Peter J. Shull, Editor(s)

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