Several Special Features of the Fatigue Strength of Glass Fiber Reinforced Plastics,

The observations of many authors confirm that the fatigue curve for glass reinforced plastics does not have a horizontal asymptote. In the case of reinforced plastics there is therefore no clear expression of the limits of fatigue. This is a question merely of the conditional fatigue strength of glass reinforced plastics for a certain given basis of investigation. It is also known that for a sufficiently high frequency of tests noticeable initial heating of glass reinforced plastic samples is observed as a result of intensive hysterisis heat production. We conducted direct measurment of the surface temperature of a cantilivered sample of KAST-V glass fiber reinforced plastic during cyclic bending. At the beginning of the test the temperature increases and then stabilizes. In the case of high levels of stress, progressive failure is observed until a temperature equilibrium is established. We conducted fatigue tests of rectangular samples 130 X 30 X 6 mm made of KAST-V glass fiber reinforced plastic. The sample, which was rigidly attached at one end and hinged connected to a vibrator arm at the other end, was investigated for two-dimensional cross-sectional bending with a constant amplitude of oscillations until failure. Author, modified-PL.