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Influence of external environments on fatigue crack growth in epoxy resin
Author(s) -
Mizutani K.,
Iwatsu T.
Publication year - 1983
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760230403
Subject(s) - materials science , epoxy , composite material , crack closure , fracture mechanics , paris' law , stress intensity factor , penetration (warfare) , crack growth resistance curve , strain energy release rate , stress concentration , fracture (geology) , operations research , engineering
A fatigue crack propagation in an epoxy resin in the presence of organic solvents or water was studied from the viewpoint of fracture mechanics. The fatigue crack growth rate ( da/dN ) of the resin under various stress‐intensity‐factor ranges (Δ K l ) was measured using a tapered double‐cantilever beam specimen. In air environment, plots of da/dN against Δ K l were found to be represented by the Paris equation: da/dN = C (Δ K l ) n , where C and n are empirical constants. In this case, the constant n was about 6.5. The fatigue crack growth rate in the presence of organic solvents decreased to 1/10 ∼ 1/4 of that in air environment at the same Δ K l . It was considered that a penetration of the solvent molecules into the resin enlarged a region of plastic deformation near the crack tip. Therefore, more fracture energy was needed for the growth of the fatigue crack. Also, observations of the fatigue fracture surfaces suggested that a large plastic deformation occurred at the crack tip in the presence of solvents.