Carbon fiber reinforced plastics (CFRP) have high specific modulus and specific strength, so that they have been used to the 1st or 2nd structural material for airplanes, marine ships and so on. These CFRPs for structural-use generally have 2 or 3 dimensional preform configurations, which are used properly for each purpose. Especially textiles are the typical 2 dimensional preform configurations, and those manufacturing processes are based on the traditional textile technology so that textiles as the FRP's preform have variety. On the other hand, the evaluation of damage tolerance of the FRP is one of the remarkable topics so that considerable researches have been conducted. Especially impact damage on FRP has been evaluated by non-destructive evaluation methods, such as X-ray computer tomography, ultrasonic scanning device and so on. However, almost all of these non-destructive evaluation methods hardly image the distribution of internal damages such as small cracks and hardly probe the damage growth behavior either. In order to clarify above mentioned damages inside the FRP, it is necessary to cut out the FRP at the damage area and to observe with optical or electron microscopy. This study focuses on the plain woven fabric which is one of the textiles, and evaluates the effects of impact damage on plain woven CFRP laminates manufactured by the vacuum assisted resin transfer molding (VARTM) method. The impact damage inside the material is evaluated by both non-destructive evaluation methods and optical cross-sectional observation. As non-destructive evaluation methods, the thermo-elastic stress analyzer and ultrasonic scanning device are employed. The former can measure in-situ the surface stress distribution under cyclic testing, and the latter can probe internal damages such as delamination. In addition, actual internal damages and their distribution are observed with cross-sectional images captured by an optical microscope. The non-destructive method and the optical observation method are compared with each other, and the internal damage distribution is clarified.
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