Evaluation of Porosity on the Hoop Tensile Strength of Filament-wound Fiber Reinforced Glass Epoxy Composite Tubes

Abstract

The evaluation of the porosity influence on the hoop tensile strength of glass fiber epoxy composite tubular components was studied. To measure the strength of components, test specimens were prepared in accordance with the ASTM 2209-19a standard. Prior to destructive testing, non-destructive tests were employed. Non-destructive observations include optical microscopy analysis, SEM analysis, and X-ray computed tomography. The purpose of these observations was to verify the presence of porosity and to evaluate its effect without subjecting the specimens to destructive testing. It was seen that not only the percentage of porosity in the specimens was important, but also the spatial distribution of the porosity is crucial. When the porosity approaches similar to 4% and is concentrated near the inner radius of the specimens, the hoop tensile strength decreases dramatically. A difference of similar to 25% in hoop tensile strength was found between specimens with high, localized porosity, and without porosity, which can be called control group. On the other hand, when the porosity is far from the position where the load is applied in destructive testing, its strength-reduction influence becomes less present, yet still prominent.