HYGROTHERMAL DEGRADATION IN GLASS EPOXY - EVALUATION VIA STRESS WAVE FACTORS

The paper documents an experimental study on nondestructive evaluation of hygrothermally degraded glass fiber/epoxy matrix composite laminat es. Specimens were subjected to accelerated life tests, i.e. high temp erature and high pressure steam. The efficiency of the stress (ultraso nic) wave propagation through the specimens was evaluated quantitative ly, at various stages of degradation, via the so-called stress wave fa ctors (SWFs). Scanning electron micrographs were taken at some stages of degradation. In addition, the specimens were tested in bending mode . All measurements are correlated with the SWFs.