1992 Volume 41 Issue 465 Pages 804-807
In order to clarify the differences of fatigue behavior of polyamides with different molecular structures, the stress-controlled fatigue tests were carried out on polyamide 46, polyamide 66 and polyamide 6 by means of tension-tension type fatigue tester. Fatigue lifetime of polyamides 46 and 66 was longer than that of polyamide 6 under the stress amplitude investigated.
Polyamides 46 and 66 showed a thermal (ductile) failure behavior in large stress amplitude region and a brittle failure at smaller stress amplitudes. Polyamide 6 showed only the thermal failure behavior at stress amplitude tested in this study. The transition stress level from termal to brittle failure for polyamide 46 was higher than that for polyamide 66.
Fatigue lifetime of polyamide 46 under constant stress amplitude was found to be independent of test frequency, while that of polyamide 66 and 6 decreased with test frequency.
