Influence of moisture-induced stress on in situ fiber strength degradation of unidirectional polymer composite
✍ Scribed by Kin Liao; Yen-Mei Tan
- Publisher
- Elsevier Science
- Year
- 2001
- Tongue
- English
- Weight
- 146 KB
- Volume
- 32
- Category
- Article
- ISSN
- 1359-8368
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✦ Synopsis
A three-phase concentric cylinder model is used to estimate moisture-induced internal stress in unidirectional polymer composite. It is found that moisture-induced tensile stress on the ®ber is substantial when absorbed moisture level in the polymer matrix is high. It is also shown that the stress-state of the ®ber is not signi®cantly changed by inclusion of an interphase layer with properties similar to the matrix. The consequence of moisture-induced internal stress is that glass ®bers are subjected to stress corrosion, even under no externally applied stress. It is found, by measuring the size of the fracture mirrors of failed glass ®bers in model composites, that the in situ tensile strength of Eglass ®bers in an epoxy matrix composite was degraded at a faster rate compared to the case of stress-free aging of glass ®bers. Thus it is concluded that moisture-induced tensile stress in glass ®bers plays an important role in strength degradation of unidirectional composite under environmental aging.