Fatigue Crack Growth and Retardation Using Polycarbonate.

摘要

This experimental study investigated the 'retardation'effects observed when tensile overloads were applied during fatigue tests of polycarbonate, a transparent polymer. Fatigue cracks were grown in 4-point bend polycarbonate specimens at constant stress intensity ranges in order to obtain constant fatigue crack growth rates. Peak overloads were then applied to the specimens in order to investigate their effects on subsequent crack growth. Simple optical methods were used to observe and photograph the crack tip front at the center of the specimen. Tensile overloads were shown to retard fatigue crack growth in polycarbonate in a manner similar to that observed in metals. Crack tip blunting and crack closure appeared to be associated with the retardation mechanism;however,their exact relationship was not investigated. It was concluded that polycarbonate offers potential as a model material for further retardation studies. (Author)