EFFECTS OF TEMPERATURE ON STRESS-RUPTURE TIMES IN GLASS POLYESTER LAMINATES

The stress-rupture times of glass fiber-reinforced plastics in water are temperature-dependent. Increasing the temperature increases the diffusion coefficient of a liquid in a given matrix, and may also increase the fracture toughness of the resin. The effects of these two parameters on the rupture lifetimes oppose each other, and so the overall outcome could be either an increase or a decrease in failure time. This problem is illustrated by experiments with glass fiber-reinforced polyester laminates in water. The failure times were greater at 45 degree C than at either 60 degree C or 30 degree C. Acoustic emission experiments suggested that resin microcracking was extensive at 30 degree C but was much less at the higher temperatures, although the glass transition temperature was outside the experimental range. The sequence of events leading to failure is described.