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Effects of time and temperature on the tension‐tension fatigue behavior of short fiber reinforced polyamides
Author(s) -
Jia Nanying,
Kagan Val A.
Publication year - 1998
Publication title -
polymer composites
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.577
H-Index - 82
eISSN - 1548-0569
pISSN - 0272-8397
DOI - 10.1002/pc.10114
Subject(s) - materials science , composite material , ultimate tensile strength , fatigue limit , tension (geology) , polyamide , glass fiber , stress (linguistics) , fiber , linguistics , philosophy
Abstract To support the fatigue design of the cyclically stressed plastics parts, such as automotive under‐the‐hood and exterior components, we analyzed the short‐term and long‐term mechanical performance (tensile strength, fatigue strength, and fatigue life) of short glass fiber reinforced polyamides PA 6 and PA 66. Comprehensive tension‐tension fatigue tests were conducted with reference to the latest ASTM, ISO, and Japanese industrial standards for plastics, at temperatures from −40°C to 121°C, on materials aged at 121°C for 0, 100, 500, and 1000 h. Tests were conducted at a loading frequency f = 5 Hz, stress ratio R = 0.1, and in a wide range of cycles to failure from 2 × 10 3 to 2 × 10 6 . Without aging and for both PA 6 and PA 66, the highest fatigue strength or fatigue life was found at −40°C; it decreased significantly at 23°C, and decreased further at 121°C. The fatigue strength of PA 6 was found to be higher than that of PA 66 at −40°C, but the reverse was seen at 23°C. At 121°C, the fatigue strengths of PA 6 and PA 66 were virtually the same. Aging at 121°C improved the tensile strength of PA 6 and PA 66 as aging time increased from 100 to 1000 h, and this process seemed to be more influential for PA 6.