2015 年 64 巻 8 号 p. 662-667
In this study, we investigated the effects of the cross-head speed during tensile testing on the fracture strength of notched plates of glass-fiber-reinforced syndiotactic polystyrene (GF/SPS). GF/SPS is well suited for the manufacture of electronic components for hybrid electric vehicles because of its high heat resistances, electrical properties, and low specific gravity. GF/SPS plates containing 30% e-glass fiber by weight were prepared by injection molding. The notch-root radii were 0.5, 1, and 2 mm, while the notch depth ranged from 2 to 5 mm. The tensile tests were performed at cross-head speeds of 104, 103, 102, 1, 8.33×10-3 and 8.33×10-5 mm/s at a temperature of 23℃. It was found that all the notched specimens failed in a brittle manner at the maximum load. The maximum elastic stress at fracture was determined from the notch-root radius and the time to fracture but was independent of notch depth. The obtained results could be explained of the basis of the severity of the stress fields near the notch roots of the specimens. Furthermore, it was verified that a fracture criterion based on the severity of the stress fields near the notch roots is applicable in the case of GF/SPS.