THE EFFECT OF TEST CONDITIONS ON THE FATIGUE PROPERTIES OF A PHENOLICCOMPOSITE

The paper reports experimental work carried out on a composite with a phenolic matrix and reinforced with glass fiber. The fatigue results w ere obtained on both unidirectional fiber composites and crossed fiber composites. For unidirectional fiber composites the two glass fiber t reatments were investigated. All the fatigue tests were carried out on a mechanical fatigue machine equipped with frequency control and a fu rnace. The unidirectional composites were tested in the frequency rang e from 1.5 to 25 Hz and in the temperature range from 20 to 200 degree s C. The crossed composites were tested in the frequency range from 2 to 20 Hz at 20 degrees C. The paper discusses and draws conclusions ab out the fatigue damage in terms of variation of Young's modulus, the i nfluence of the temperature and frequency on the fatigue strength and surface temperature variation during testing.