The authors conducted uniaxial and biaxial (Ratio of stress in warp and fill = 1 : 1) stress relaxation and creep testings on a PTFE-coated glass fiber and PVC-coated polyester plain-weave fabric, including iterative stress relaxation testings. The applied stress magnitudes for the testings were 3 to 7 kgf/cm, the durations of a unit stress relaxation were 10, 120 minutes (for the iterative relaxation) and 24 hours, the durations of creep testings were 12 and 24 hours, and the temperature conditions taken only for the testings on uniaxial stress conditions were 20, 40 and 60℃. Strain-, temperature-, iteration times-, stress ratio- and yarn direction-dependency on stress relaxation, and stress-, temperature-, stress ratio- and yarn direction-dependency on creep of the specimens were studied, and the useful knowledge of visco-elastic property was found out. One of the conclusion of the study is that the rate of convergence of relaxation curve highly depends on the number of times of iteration of relaxation without dependency on yarn direction, the duration of unit stress relaxation and stress ratio.
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