抄録
High-strength polyethylene-fiber-reinforced plastic (DFRP) pipes show different circumferential thermal strains between outer and inner surfaces with cooling. The strains were measured by means of strain gage on DFRP, glass-fiber-reinforced plastics (GFRP) and DF/GF hybrid composite (DGFRP) pipes to establish the design methodology of the coil bobbin showing negative thermal expansion coefficient in circumferential direction at the outer surface. The difference of outer and inner circumferential thermal strain decreased with increase of the ratio of inner diameter vs. thickness. The difference increased with the increase of the degree of anisotropy of thermal expansion coefficients in UD-FRP. The difference of outer and inner circumferential thermal strains was shown the largest value by DFRP, and the smallest one by GFRP. The difference was confirmed to be designed with the material parameters of UD-FRP.
