Effect of fibre orientation on the fatigue behaviour of a short glass fibre reinforced polyamide-6

The effect of fibre orientation on the fatigue strength of a short glass fibre reinforced polyamide-6 has been investigated. Tension–tension axial fatigue tests were conducted with specimens extracted from injection moulded plates. Specimens were cut out of plates with different orientations with respect to the longitudinal axis of plates, and therefore displayed different orientations of the reinforcing fibres. Results are presented in the form of S–N curves, showing the variation of the fatigue strength as a function of the specimen orientation. The experimental data, both tensile and fatigue tests, have been compared with values predicted by a failure criterion derived from the Tsai–Hill formula. The influence on the fatigue lives of the fibre orientation distribution in the thickness of the specimen is discussed.