SYMPOSIA PAPER Published: 01 January 1984
STP32559S

Effects of Specimen Configuration and Frequency on Fatigue Crack Propagation in Nylon 66

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Fatigue crack propagation (FCP) rates were measured in nylon 66 as a function of test frequency using center-cracked-tension (CCT) and wedge-open loading (WOL) specimens. In order to enhance any effects of stress- and frequency-induced changes in the dynamic modulus and to maximize the capability for hysteretic heat generation, the nylon was equilibrated to a water content of 4.7% by weight. For this water content the glass transition region of the material occurs at around the fatigue test temperature. FCP rates determined using CCT specimens were found to be consistently higher at all frequencies than those using WOL specimens. In addition, hysteretic heat-up measured at the crack tip and across the whole unbroken ligament was higher in the CCT specimens. These results are related to the differences in the far field stress profiles and their effect on the relative specimen stiffness and on the heat generation capability. Effects of test frequency are discussed in terms of changes in strain rate and the beneficial and detrimental effects of local crack tip and general specimen heating.

Author Information

Lang, RW
Materials Research Center, Lehigh University, Bethlehem, Pa.
Hahn, MT
Materials Research Center, Lehigh University, Bethlehem, Pa.
Hertzberg, RW
Materials Research Center, Lehigh University, Bethlehem, Pa.
Manson, JA
Materials Research Center, Lehigh University, Bethlehem, Pa.
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Details
Developed by Committee: E08
Pages: 266–283
DOI: 10.1520/STP32559S
ISBN-EB: 978-0-8031-4900-7
ISBN-13: 978-0-8031-0208-8