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Rate dependent fracture behavior of highly cross-linked epoxy resin
Journal
Engineering Failure Analysis
ISSN
13506307
Date Issued
2022-10-01
Author(s)
Mishra, K.
Brassart, L.
Singh, A.
Abstract
The fracture behavior of highly cross-linked epoxy resin under plane strain conditions for crack tip strain rates spanning over four orders of magnitude (10-4 −10-1 s−1) has been examined. The plane strain fracture toughness initially decreases with increasing crack tip strain rate (∊̇tip) and saturates at ∼ 0.8 MPa-m−0.5 after ∊̇tip ∼ 0.02 s−1 is attained. For all the fracture specimens, a fracture process zone (FPZ) forms ahead of the sharp pre-crack prior to catastrophic failure due to the intensified stresses ahead of the crack tip. This FPZ region consists of crazes that govern the micro mechanism of fracture and this was explicitly proved using in-situ testing in a scanning electron microscope. For low strain rates, crazing in the FPZ is expected to be dominated by chain disentanglements, with craze openings more than 200 nm, whereas, chain-scission is expected to dominate at higher strain rates, with lower craze openings of ∼ 150 nm.
Volume
140
Subjects