Accession Number : AD0769926

Title :   Fatigue Crack Growth and Retardation Using Polycarbonate.

Descriptive Note : Master's thesis,

Corporate Author : AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OHIO SCHOOL OF ENGINEERING

Personal Author(s) : Banasiak,Daniel H.

Report Date : JUN 1973

Pagination or Media Count : 71

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

Descriptors :   (*Fracture(Mechanics), Models), (*Fatigue(Mechanics), Models), (*Polyester plastics, Fatigue(Mechanics)), Crack propagation, Loads(Forces), Metals, Stresses, Tensile properties, Toughness, Stress strain relations, Theses

Subject Categories : Metallurgy and Metallography
      Plastics

Distribution Statement : APPROVED FOR PUBLIC RELEASE