Fracture Patterns in Glass and Glassy Polymers

The abstract of a new report made available by the National Institute of Justice states, "The study of fractures of glass, glassy type materials, and plastic has long been of interest to the forensic community."

In "Determination of Unique Fracture Patterns in Glass and Glassy Polymers," authors Frederic A. Tulleners, M.A. and John Thornton, D. Crim., and Allison C. Baca, B.S. of the University of California - Davis "documented the very controlled fracture patterns of 60 glass panes, 60 glass bottles, and 60 plastic tail light lens covers. The pane and bottle specimens were fractured with three different types of penetration tips: sharp tip, round tip, and blunt tip. Two basic methods were used to initiate the fractures—dynamic impact from a dropping weight and static pressure from an Instron® 4204 Tensile Tester. The fracture patterns were then documented in great detail in such a manner that allowed the analyst to inter-compare the fracture patterns. This subsequent comparison illustrated the uniqueness of all of the fracture patterns we observed in window glass, bottle glass, and plastic lens materials. Thus, we are substantiating the individuality of glass and polymer fractures under closely controlled conditions."

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