An averaged strain energy density based approach to predict the static notch effect in short fibre composites. Part 2: experiments and validation

In this paper, an Averaged Strain Energy Density (ASED)-based equivalent stress parameter, derived from the theoretical framework presented in the companion paper, is employed to assess the static strength of notched, short glass fibre-reinforced composites. To this end, quasi-static tensile tests were conducted on specimens composed of 40 wt% short glass fibre-reinforced polyphenylene sulfide (SGF-PPS), which were manufactured via injection moulding with various notch geometries. Additionally, data from previous studies on notched specimens of milled 40 wt% SGF-PPS and 20 wt% short carbon fibre-reinforced polyamide (SCF-PA) were analysed. Computed tomography revealed that the injection moulding process significantly influenced fibre distribution, particularly in the vicinity of the notches. Furthermore, post mortem scanning electron microscopy analyses across all materials identified fibre–matrix debonding, matrix plastic deformation and fibre failure as the primary damage mechanisms. While these mechanisms were independent of notch geometry, they were strongly influenced by the fibre orientation. The results demonstrated that the ASED-based equivalent stress parameter successfully correlates the experimental static strength data within a narrow scatter band, thus being an effective criterion for the assessment of the notch effect of SFCs under static loadings.