Combined effect of notches and fibre orientation on fatigue behaviour of short fibre reinforced polyamide

The combined effect of notches and fibre orientation on static and fatigue strength of short glass fibre reinforced polyamide 6 was studied using notched specimens that, by proper design of the mould, could be injection moulded through gates of two different sizes and locations. The results showed that the values of the tensile and fatigue notch factors for a particular geometry were strongly influenced by varying the way specimens were injected. A new experimental method was applied to investigate whether the observed differences in mechanical behaviour of specimens having the same geometry were caused by different fibre orientation distributions. Synchrotron light micro-tomography allowed for visualization of local fibre orientation at notches and the obtained images of the internal structure of the samples were subsequently analyzed by a global morphological parameter, the mean intercept length. Results were also discussed in light of the full displacement field measured by digital image correlation.