Tensile Strength of Poly-p- Phenylene Benzobisoxazole (PBO) Fiber with Kinking Damage

In this study, tensile strength of PBO fiber with kink band was investigated in single fiber (monofilament) tensile tests. The kink band was introduced by the wrapping fiber bundle to the steel bars with several diameters. Weibull analysis on the obtained tensile strength was carried out to discuss the strength in the on region of kink band. It was found that the tensile strength of PBO fiber decreases with the increase in kink band density. Kink bands act as defects that degrade the tensile strength. A Weibull analysis demonstrated that the concept of effective volume explains the tensile strength of PBO fiber. The reduction of tensile strength at low bar diameters from the appearance of kink bands is not due to changes in strength near the kink bands but rather to the increase in kink band density.