共焦点顕微ラマン分光法を用いた炭素繊維強化複合材料中の残留応力ならびに内部応力マッピング

概要

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In this study, residual and internal stresses of PAN-based carbon fiber in CFRP were measured by confocal Raman microspectroscopy with sub-micro scale spatial resolution. For single carbon fiber, the relationships between the change of Raman bad shift and applied stress were obtained by single fiber tensile test. The relationship for Raman band peak at 2691cm-1 indicated high linearity and high stress resolution. Residual stresses of carbon fiber in CFRP were determined by using the relationship for 2691cm-1 Raman line. Residual stresses of several carbon fibers in 4∼7μm depth from the specimen surface were measured. Then, residual stresses were compressive and the mean stress was about -625MPa. The mapping measurement of residual stress of carbon fiber in CFRP was conducted. The fibers on the specimen surface had low compressive stress, and fibers in matrix had high compressive stress. Last, the mapping measurement of residual and internal stresses near the crack tip in CFRP under mode I loading was conducted. Change of stress field around the crack tip was observed from differences between residual and internal stress distributions. Therefore, the availability of confocal Raman microspectroscopy to stress evaluations of CFRP was confirmed.