ABSTRACT:

The effect of hardener on the tensile fracture behavior of carbon fiber reinforced plastic, CFRP, was investigated using smooth and notched tensile specimens at various temperature ranges. The hardeners used were an acid anhydride and an amine line. Experimental results were discussed in terms of linear notch mechanics. It was found that tensile strength and fracture morphology of center notched CFRP plates strongly depended on the test temperature. The brittle-ductile transition temperatue, Tr, is slightly affected by the notch tip radius, ζ, regardless of hardeners. Furthermore, the value of Tr was about 40K higher for Material B than for Material A. In the case of the brittle fracture mode, the fracture occurs under the condition of constant critical elastic maximum stress, σ maxc " which is determined by ζ alone. In the case of the ductile fracture mode, the fracture occurs under the condition of constant nominal stress in the net section, regardless of The values of cr at the zone of brittle fracture for Material B were greater by about 15% than that for Material A, regardless of the test temperature.

1. INTRODUCTION

CFRP in which the polyacrylonitrile (PAN)based carbon fiber was combined in a resin matrix is currently being considered for use in aircraft, artificial satellites and other high-performance vehicles where low weight and high -stiffness are important. Many studies on fatigue and static fracture have been made to keep structures working safely using PAN-based CFRP(Hull, 1981, Morita, 1984, Fujii and Zako, 1978). However, these composite materials are expensive. A commercially available pitchbased CFRP has been developed by S.Otani(1965) and is expected to be much more economical to produce than PAN-based carbon fiber. On the other hand, a change in temperature and/or the presence of a notch or a hole affect the composite materials.

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