TY - JOUR
T1 - Environmental effects on shear delamination of fabric-reinforced epoxy composites
AU - Kenig, S.
AU - Moshonov, A.
AU - Shucrun, A.
AU - Marom, G.
PY - 1989/1
Y1 - 1989/1
N2 - Composite materials are prone to delamination failure due to their laminated structure. Hence, this failure mode has been the subject of numerous investigations. In the present study the residual Mode II delamination fracture toughness was characterized following exposure to low cycle fatigue loading and moisture at 50°C. The composites investigated included balanced fabric-epoxy systems composed of glass, aramid and carbon fibres. Experimental results have shown that the matrix and fibre/matrix interface dominated behaviour in shear loading and was insensitive to short-term exposure to both fatigue and moisture. Moreover, the carbon/epoxy material exhibited enhanced resistance to Mode II delamination after short exposure due to relaxation of the processing induced thermal stresses. However, long exposure caused damage to both the matrix and the fibre matrix interface, manifested in reduction of the strain energy release rates at failure. Fractographs supported the experimentally determined results. While unconditioned failure surfaces were typified by shear hackles, fatigued specimens indicated gradual elimination of the hackles, fibre fracture and matrix abrasion. When the composites were moisturized, examinations of the fracture surfaces revealed plasticization of the matrix following short-term conditioning with gradual disappearance of the typical shear striations and appearance of voids, following long-term exposure.
AB - Composite materials are prone to delamination failure due to their laminated structure. Hence, this failure mode has been the subject of numerous investigations. In the present study the residual Mode II delamination fracture toughness was characterized following exposure to low cycle fatigue loading and moisture at 50°C. The composites investigated included balanced fabric-epoxy systems composed of glass, aramid and carbon fibres. Experimental results have shown that the matrix and fibre/matrix interface dominated behaviour in shear loading and was insensitive to short-term exposure to both fatigue and moisture. Moreover, the carbon/epoxy material exhibited enhanced resistance to Mode II delamination after short exposure due to relaxation of the processing induced thermal stresses. However, long exposure caused damage to both the matrix and the fibre matrix interface, manifested in reduction of the strain energy release rates at failure. Fractographs supported the experimentally determined results. While unconditioned failure surfaces were typified by shear hackles, fatigued specimens indicated gradual elimination of the hackles, fibre fracture and matrix abrasion. When the composites were moisturized, examinations of the fracture surfaces revealed plasticization of the matrix following short-term conditioning with gradual disappearance of the typical shear striations and appearance of voids, following long-term exposure.
KW - environmental effects
KW - fabric-reinforced epoxy composites
KW - failure mode
KW - fractography
KW - shear delamination
UR - http://www.scopus.com/inward/record.url?scp=0024479709&partnerID=8YFLogxK
U2 - 10.1016/0143-7496(89)90145-0
DO - 10.1016/0143-7496(89)90145-0
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AN - SCOPUS:0024479709
SN - 0143-7496
VL - 9
SP - 38
EP - 45
JO - International Journal of Adhesion and Adhesives
JF - International Journal of Adhesion and Adhesives
IS - 1
ER -