Combined Effect of Notches and Fibre Orientation on Fatigue Behaviour of Short Fibre Reinforced Polyamide

Abstract

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 visualisation 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.

An experimental investigation of the combined influence of notch size and fibre orientation on the fatigue strength of a short glass fibre reinforced polyamide 6

“…The present research follows the path traced by a previous work [15] where the effect of circular notches having a relatively large radius of 7.5 mm was studied for small injection-molded plates, in conjunction with the effect of different fiber orientation patterns obtained by varying the type and position of the injection gate.…”

“…The mold employed in [15] was modified in order to obtain small plates with lateral V-shaped notches with tip radii of 0.5, 1 and 2 mm. All three types of specimen were injection molded through either a film gate on the top face of specimens or a side gate on a lateral face of the specimens.…”

Characterization of fracture properties of thin aluminuminclusions embedded in anisotropic laminate composites

“…These interesting characteristics foster the continuous development of the methodology with the reduction of the elaboration time, the optimization of the computer algorithms and the improvement of the measurement precision. Consequently, the application field of this technique is progressively enlarged and recent contributions include metals [3], wood [4], transparent media [5] and plastics [6,7] among others. In this investigation, the interpretation of the large amount of experimental data recovered by DIC is supported by the numerical simulation of the tests.…”

Phase contrast micro-tomography and morphological analysis of a short carbon fibre reinforced polyamide

“…On the contrary, in short fibre reinforced composites fibres are dispersed along all directions even when preferred orientations are present, so that the 3D MIL locus can be approximated by an ellipsoid [7,11,12] and a compact tensor notation can be used to define fibre arrangement properties. In the second order MIL fabric tensor thus defined, eigenvectors correspond to the principal directions of the anisotropic structure, while the normalized eigenvalues H i can be considered a measure 10 of fibre distribution along these directions.…”

“…Characterization of anisotropy by MIL, commonly utilized in biomechanics and geology, was adopted for SFRP samples. In this way, it was possible to identify local preferred fibre directions and anisotropy degrees in glass fibre reinforced thermoplastic polymers [7,11,12].…”