Authors: S Barbouchi V Bellenger A Tcharkhtchi Ph Castaing T Jollivet
Publish Date: 2007/02/18
Volume: 42, Issue: 6, Pages: 2181-2188
Abstract
The aim of this study is to evaluate the effect of the humidity on the long term behaviour of glass fiber reinforced thermoplastic in fatigue Two sets of samples were studied one set contained 02 wt of water the second 35 wt The fatigue tests are performed at a 10 Hz frequency at room temperature and two various relative humidity ratios 50 RH and 96 RH The S–N curve of dried samples 02 is above the one of humid samples 35 the endurance limit at 107 cycles for dried samples is equal to 40 MPa against 35 MPa for the second set For a given strain the fatigue life is higher for humid samples because the induced stress is much lower due to the plasticizing effect of water Though the tests are carried out at room temperature 23 °C the sample temperature at the surface reaches values higher than Tg and whatever the applied strain the matrix is in a rubbery state when the fracture occurs On the basis of SEM examinations the following scenario is proposed crack initiation at the fiber end crack propagation along the fiber sides going with debonding then crack propagation in the rubbery matrix
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