Property ModellingStrength predictions by applied effective volume theory in short-glass-fibre-reinforced plastics

Uniaxial stresses were evaluated under flexural, tensile and torsional tests with various fibre volume fractions, vf, and specimen sizes to develop simple and effective predictions on the quasi-static strength of compression-moulded short-glass-fibre-reinforced phenolic resin. The distributions in fibre orientation and fibre length were represented by Weibull and normal distributions, regardless of vf. The size effect was characterized by uniaxial stress testing and Weibull statistical analysis. The effective volume theory (EVT) was used to predict the quasi-static strength for vf of 0.0 with a scale parameter of 108.2 MPa and a shape parameter of 8.92. Strength prediction while considering Veff and vf was proposed by applying the EVT of the resin matrix to a method that combined a modified rule of mixtures and the Thai-Hill failure criterion. The measured value agreed well with the prediction for each Veff and vf, regardless of manufacturing defects in the matrix resin.