Statistical Analysis on Morphology Characteristic of Voids in CFRP Composites

The relations of porosity and parameters including average length (AL), average width (AW) and ratio of width to length (RWL) of voids in 16-groups of carbon fiber reinforced polymer (CFRP) composite samples with porosity (P) ranges in 0.03% - 4.96% had been investigated using metallographic observation and statistical analysis. The results show that the void morphology in CFRP composites satisfied the statistical property on the whole. Most of voids were round-shape under the condition of 0.03%≤P<0.5%, and the range of AL, AW and RWL were 10-50 μm, 10-30 μm, and 0.5-0.8, respectively. When 0.5%≤P<3.0%, most of voids were translated into ellipse and the range of AL, AW and RWL were 50-70 μm, 20-30 μm and 0.5-0.6, respectively. When 3.0%≤P≤4.96%, most of voids were long stripe and the range of AL, AW and RWL were 50-100 μm, 30-40 μm and 0.35-0.5, respectively. Meanwhile, morphology of voids in CFRP composites also had random property, such as large difference of size, shape and distribution of voids existing in the samples with different porosity and even different location of the same sample.