caa a22 4500 469124385 CHVBK 20180323133147.0 cr unu---uuuuu 170328e19920601xx s 000 0 eng 10.1007/BF00032511 doi (NATIONALLICENCE)springer-10.1007/BF00032511 An energy analysis of crack initiation and arrest in epoxy [Elektronische Daten] [A. Chudnovsky, A. Kim, C. Bosnyak] The objective of this work is to study fracture processes such as crack initiation and arrest in epoxy. A compact tension specimen with displacement-controlled loading is employed to observe multiple crack initiations and arrests. The energy release rate at crack initiation is significantly higher than that at crack arrest, as has been observed elsewhere. In this study the difference between these energy release rates is found to depend on specimen size (scale effect), and is quantitatively related to the fracture surface morphology. The scale effect, similar to that in strength theory, is conventionally attributed to the statistics of defects which control the fracture process. Triangular shaped ripples, deltoids, are formed on the fracture surface of the epoxy during the slow sub-critical crack growth, prior to the smooth mirror-like surface characteristic of fast cracks. The deltoids are complimentary on the two crack faces which excludes any inelastic deformation from consideration. The deltoids are analogous to the ripples created on a river surface downstream from a small obstacle. However, in spite of our expectation based on this analogy and the observed scale effect, there are no ‘defects' at the apex of the deltoids detectable down to the 0.1 micron level. This suggests that the formation of deltoids during the slow process of sub-critical crack growth is an intrinsic feature of the fracture process itself, triggered by inhomogeneity of material on a sub-micron scale. This inhomogeneity may be related to a fluctuation in the cross-link density of the epoxy. Kluwer Academic Publishers, 1992 Chudnovsky A. Department of Civil Engineering, Mechanics and Metallurgy (M/C 246), University of Illinois at Chicago, P.O. Box 4348, 60680, Chicago, Illinois, USA aut Kim A. Department of Civil Engineering, Mechanics and Metallurgy (M/C 246), University of Illinois at Chicago, P.O. Box 4348, 60680, Chicago, Illinois, USA aut Bosnyak C. The Dow Chemical Company, Polycarbonate R&D, Highway 227, B-1470, 77541, Freeport, Texas, USA aut International Journal of Fracture Kluwer Academic Publishers 55/3(1992-06-01), 209-222 0376-9429 55:3<209 1992 55 10704 https://doi.org/10.1007/BF00032511 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00032511 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Chudnovsky A. Department of Civil Engineering, Mechanics and Metallurgy (M/C 246), University of Illinois at Chicago, P.O. Box 4348, 60680, Chicago, Illinois, USA aut NATIONALLICENCE 700 1- Kim A. Department of Civil Engineering, Mechanics and Metallurgy (M/C 246), University of Illinois at Chicago, P.O. Box 4348, 60680, Chicago, Illinois, USA aut NATIONALLICENCE 700 1- Bosnyak C. The Dow Chemical Company, Polycarbonate R&D, Highway 227, B-1470, 77541, Freeport, Texas, USA aut NATIONALLICENCE 773 0- International Journal of Fracture Kluwer Academic Publishers 55/3(1992-06-01), 209-222 0376-9429 55:3<209 1992 55 10704 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer