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Comparison of fast fracture properties of thermoplastics
Author(s) -
Dear John P.
Publication year - 1996
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.10515
Subject(s) - materials science , composite material , fracture (geology) , fracture mechanics , limiting , crack closure , stress (linguistics) , polyethylene , crack growth resistance curve , polycarbonate , structural engineering , mechanical engineering , linguistics , philosophy , engineering
The fast fracture behavior of polyethylene, polycarbonate and poly(methyl methacrylate) are compared for two different thicknesses of material. The aim was to make fracture measurements under precisely defined steady load conditions after the material has reached a stress relaxed state. It was essential that the experimental technique provided good isolation between crack initiation and crack propagation. This was achieved in small rectangular shaped specimens by adding a tongue to one side extending the intended crack path. A fast crack was initiated in the tongue to propagate into the main section after it had been loaded and allowed to stress relax. When necessary the tongue was embrittled by cooling so a crack can be initiated with minimum force. This new method obtains the threshold load to just maintain crack propagation and also the increase of crack velocity with load above this threshold up to the limiting condition.