ISSN: 0090-3973
Page Count: 6

Effect of Specimen Thickness on the Long-Life Fatigue Performance of a Randomly-Oriented Continuous-Strand Glass-Mat-Reinforced Polypropylene Composite

Little, RE
Professor,The University of Michigan-Dearborn,MI,

(Received 19 February 1996; accepted 31 January 1997)

Abstract

This paper summarizes an experimental study of how three specimen thicknesses—⅛, 3/16, and ¼ in. (3.18, 4.76, and 6.35 mm)—affect the long-life fatigue performance of a thermoplastic composite material with 40% randomly-oriented continuous-strand glass in a polypropylene matrix (Azdel). Axial-load and four-point-bending fatigue tests were conducted to compare (1) the respective median logarithmic fatigue lives for a common alternating stress amplitude and (2) the respective estimated median fatigue strengths at 10⁷ stress cycles. Both the median logarithmic fatigue life and the median fatigue strength decreased markedly when the specimen thickness was increased from ⅛ to 3/16 in. (from 3.18 to 4.76 mm). However, in each case, no further decrease was statistically evident when the specimen thickness was increased from 3/16 to ¼ in. (from 4.76 to 6.35 mm).

Keywords:
composite material, long-life fatigue behavior, thickness effect, statistical analysis of variance, up-and-down test method, median fatigue strength, optimal test methods, Azdel

Paper ID: JTE11359J
DOI: 10.1520/JTE11359J
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