Fatigue Behavior of Glass Fiber Reinforced Polybutyleneterephthalate

摘要

The fatigue behavior of short glass fiber reinforced PBT composites has been investigated under different environmental conditions. Exposure to water at high temperature causes embrittlement, while improved processing and exposure to high humidity cause an increase in ductility. The fatigue life is a function of the environmental conditioning, the stress level of the test and the ductility of the material. The quantity (Theta (max)/< Theta >)2 1n t(B) is independent of environmental conditioning and increases with increasing ductility. The total deformation-to-break during fatigue consists of a deformation attributable to cyclic softening and a longer term deformation that continues at nearly constant rate until failure occurs. The cyclic softening is associated with cyclic stress-strain characteristics, while longer term deformation is controlled by creep and microcavitational phenomena. Crack propagation rates in notched plates were measured. The crack propagation behavior was somewhat dependent on the stress history of the material.