STP1369

    Notched Impact Testing of Thermoplastics: A New Perspective

    Published: Jan 2000


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    Abstract

    The toughness of unreinforced thermoplastics is often high, but limited by a transition to brittle behaviour with increasing impact speed and decreasing temperature. Izod or Charpy impact strength data are widely regarded as a primary performance index for these materials, but cannot be used for quantitative design. Although fracture mechanics analysis offers a substantial advance, the impact fracture resistance for some polymers varies substantially with configuration (the shape and size of the body and the impact speed) rather than being a material constant as expected. A model of brittle impact fracture as a process of local fusion within a rapidly-loaded crack-tip craze explains this variation quantitatively. The model leads to a method of correlating impact fracture in different configurations, which is demonstrated here using a case study.

    Keywords:

    fracture mechanics, thermoplastics, impact fracture, dynamic fracture, rate, geometry, correlation


    Author Information:

    Leevers, PS
    Reader in Polymer Engineering and Research Student, Imperial College, London,

    Douglas, M
    Reader in Polymer Engineering and Research Student, Imperial College, London,


    Paper ID: STP14345S

    Committee/Subcommittee: D20.15

    DOI: 10.1520/STP14345S


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