Abstract

The tensile and fatigue properties of long unidirectional (UD) and crossply (CR) carbon fiber reinforced plastics (CFRPs) were investigated. The CFRPs in this study were fabricated from 60% CF and various resins: epoxy, polyamide (PA6), polyphenylene sulfide (PPS), and polyether ether ketone (PEEK). The ultimate tensile strength sUTS of Epoxy-CFRP was found to be about twice that of PEEK-CFRP. Relatively high tensile strengths were found for PPS- and PA6-CFRP in the thermoset resin group, although these were still only about 85% of the strength of epoxy-CFRP. The tensile and fatigue strengths of the CR-CFRPs were less than half those of the UD-CFRPs, even though high ductilities were found for the CR-CFRPs. These high ductilities can be attributed to the crosslinking fiber effect and the low proportion of CFs in the loading direction. The sUTS values of CFRPs depend not only on the tensile strengths s and volume fractions V of CF and resin (i.e., through the conventional compound law sUTS = sfiberVfiber + sresinVresin), but also on several material properties, including the wettability of the CF by the resin. On the basis of the material properties, the ultimate tensile strengths of various UD- and CR-CFRPs were well estimated numerically through a statistical analysis, which afforded better estimates than those obtained from the compound law.

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