The effect of testing temperature and volume fraction on impact energy of composites

Charpy impact tests were carried out for woven roving aramid and glass/epoxy composite specimens. Hand lay-up method was used in fabricating the composite specimens. Specimens were fabricated with the dimensions of 50 mm × 10 mm × 10 mm. In this project, the impact tests were conducted for a temperature range of 40 to −40 °C in intervals of 10 °C. Fiber volume fractions of 0.45, 0.55 and 0.65 were used. The effect of fiber volume fraction and testing temperature on the impact energy of the composite specimens were studied. Also impact testes were carried out on steel specimens of the same parameters as the composite specimens. Failure mechanism of the all tested specimens was examined also using a microscope with 100 times magnification. Results show that a slight increase on the impact energy of steel and composite specimens with temperature increase for the range of −40 to −10 °C. This was followed by a high increase in impact strength value for the steel specimens with the increase of temperature for the range of −10 to 40 °C. It was found that the aramid/epoxy support higher impact energy than the glass/epoxy at all the tested temperatures. On the other hand composite specimens fractured high fiber and matrix break at the notch side with delamination occurred on the longitudinal side of the specimens. The increase in fiber volume fraction decreases the impact energy absorbed for both of glass and aramid/epoxy.