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A fatigue crack initiation map for polycarbonate
Author(s) -
Chen T.J.,
Bosnyak C. P.,
Kao C.I.,
Chudnovsky A.
Publication year - 1993
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1993.070491106
Subject(s) - brittleness , materials science , polycarbonate , composite material , stress (linguistics) , fatigue testing , crack closure , fracture mechanics , structural engineering , engineering , philosophy , linguistics
The mechanisms of fatigue crack initiation for various stress levels and thicknesses have been determined for single‐edge notched specimens of polycarbonate and used to assemble a map. Three basic fatigue crack initiation mechanisms were identified and named as cooperative ductile (the damage zone formed ahead of crack consisting of yielded material), solo‐crack brittle (very little damage zone development), and cooperative brittle (identified as a cloud of microcracks or crazes that developed at the notch tip). With a given applied stress and within the same failure mechanism, the values of the number of cycles to crack initiation decrease with increase in thickness. The transition from cooperative ductile to solo‐crack brittle initiation mechanisms is sudden with increasing thickness. Transition from cooperative ductile to cooperative brittle with decreasing stress was less well defined. Regions where combinations of mechanisms were observed are also identified in the map. © 1993 John Wiley & Sons, Inc.