Suitable structure of thermosetting CFRP sheet for cold/warm forming

The forming processes at room temperature and under a warm condition have been investigated for carbon-fiber-reinforced plastic (CFRP) sheets consisting of thermosetting resin and continuous fibers used for mass production. While CFRPs consisting of thermosetting resin have the advantage of high strength, to subject them to press forming, in contrast to carbon-fiber-reinforced thermoplastics (CFRTPs), which consist of thermoplastic resin. When CFRP sheets are formed into the desired shape through plastic deformation, a higher-strength structural material easily applicable to mass production is obtained. To improve the formability of thermosetting CFRP sheets while retaining their strength, a suitable structure allowing plastic deformation under warm condition is proposed. The tensile stress obtained by a tensile test and the bending properties obtained by a stretch-bending test indicate the strength and formability, respectively. A stretch-bending test is a bending test in which a tensile load is placed on a sheet, and it has the characteristics of a bending test and a deep drawing test. A suitable structure containing prepreg layers to allow plastic deformation based on the relationship between the bending load and the results of specimen observations is revealed.