The influence of void content on the structural flexural performance of unidirectional glass fibre reinforced polypropylene composites

As expected, voids were found to have a negative effect on the flexural modulus and strength, which both decreased by about 1.5% for each 1% of voids. However, what is more interesting is the fact that voids actually had a clear positive effect on the beam stiffness EI, which increased by about 2% for each 1% of voids. For example, beams which contained 14% porosity exhibited about 28% higher EI than beams with less than 1% porosity. Moreover, the flexural failure load did not decrease up to a void content of 14%. On the contrary, a least square fit suggested a weak increase with void content. It can therefore be concluded that, in this case, voids actually have positive effects on the structural flexural performance.