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Predicting toughness of impact thermoplastics from high‐speed tensile data
Author(s) -
Fenelon Paul J.
Publication year - 1975
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.760150710
Subject(s) - necking , materials science , ultimate tensile strength , composite material , tensile testing , deformation (meteorology) , toughness , strain rate , stress (linguistics) , fracture toughness , forensic engineering , linguistics , philosophy , engineering
A photographic procedure is presented for evaluating uniaxial true stress‐true strain tensile behavior of thermoplastics at strain rates typical of impact situations. The advantage of combining this information with observed macroscopic material changes which occur during tensile deformation is discussed in terms of establishing parameters which define end use abuse resistance of impact thermoplastics. In particular, test parameters are evaluated which provide a direct correlation with measured bottle drop failure resistance for selected materials. These test parameters are obtained by measuring the area under true stress‐true strain curves obtained at impact strain rates. Area is measured up to the point of ultimate uniaxile tensile strain. Ultimate uniaxial tensile strain corresponds to either (a) strain at onset of necking in materials which produce necking during deformation, or (b) strain at fracture in materials which deform without necking. Measured test parameters are discussed in terms of modern theories of strength of materials. Pitfalls associated with quantitatively defining the abuse resistance of thermoplastics based on total energy for breaking, i.e., conventional numeric criterion of impact strength, it also discussed.