32 T. Ozaki et al. Fig. 4.7 Relationship between transverse crack density and stress 0 100 200 300 400 500 600 700 0 5 10 15 20 25 Stress [MPa] Transverse crack density [/cm] 82% 86% 93% 96% 100% 100% Fig. 4.8 Relationship between splitting crack density and stress 0 100 200 300 400 500 600 700 0 5 10 15 Stress [MPa] Splitting density [/cm] 82% 86% 93% 96% 100% 100% 4.4 Summary In this paper, FRP cross-ply laminates were manufactured with arbitrary degree of cure and tensile test were performed with observation of matrix cracks. From these results, it appeared that the transverse crack initiation stress was larger and the transverse crack density was lower when DOC was higher. Moreover, it appeared that many splitting cracks were generated in0ı layers when the DOC was less than 100 % due to the low toughness of resin. From these results, it was found that DOC governs damage development behavior of FRP laminates strongly. Acknowledgement This work was supported by Council for Science, Technology and Innovation (CSTI), “Innovative structural materials” of “Cross-ministerial Strategic Innovation Promotion Program (SIP)” (Funding agency: JST).
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