A Numerical Study on the Effects of Line Heating in Layered Anisotropic Carbon Fiber Composites

Abstract

Abstract Thermal effects of line heating on layered anisotropic carbon fiber composites were studied numerically. Surface temperature distributions were calculated for delaminations of different sizes placed between different fiber layers using finite difference methods. The anisotropy of thermal conductivity caused detectable effects on the surface temperature distributions that depend on the scanning direction of line heating and the velocity of the scanning. The fiber orientation had a clear effect on the image contrast, whereas the resolution showed only a slight dependency on this. The performance of the imaging method was estimated by comparing the size of the delamination defined in the numerical model to the half-measure size or the 1/e level size obtained from the computed surface temperature distributions. The defect size obtained by using the half-measure values was found to be slightly smaller and the size defined by the 1/e values larger than the actual one. The half measure criterion gave a better estimate compared to the 1/e values. However, in practice the observed size was very close to the actual one when either of the criteria is used. As expected, the lateral resolution deteriorated when the depth of the delamination was increased.