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NCJ Number: NCJ 241445   Add to Shopping cart   Find in a Library
Title: Determination of Unique Fracture Patterns in Glass and Glassy Polymers
Author(s): Frederic A. Tulleners, M.A. ; John Thornton, D.Crim ; Allison C. Baca, B.S.
Date Published: 2013
Page Count: 99
Sponsoring Agency: National Institute of Justice
US Department of Justice
Office of Justice Programs
United States of America
Grant Number: 2010-DN-BX-K219
Sale Source: NCJRS Photocopy Services
Box 6000
Rockville, MD 20849-6000
United States of America
Document: PDF 
Type: Research (Applied/Empirical) ; Research Paper
Language: English
Country: United States of America
Annotation: This study tested the hypothesis that fracture patterns in glass and glassy polymers are unique and therefore unlikely to be reproducible due to distinctive matrix imperfections.
Abstract: The study found that although some similarities were found in a limited number of specific fracture lines, the overall patterns were not duplicated. The fracture patterns of plastic lenses exhibited some general similarities, such as the center of many of the lenses breaking completely out of the lens. They also had a tendency to fracture along the mold lines of the lens; however, there were no duplicates of overall fracture patterns. Thus, the report urges caution in evaluating the uniqueness of fracture in this type of material. In supporting the theory that coincidental duplication fracture patterns are highly unlikely, this research aids practitioners in substantiating court testimony about the significance of fracture matching of broken glass and polymers materials. This study documented the controlled fracture patterns of 60 class panes, 60 class bottles, and 60 plastic tail light lens covers. The pane and bottle specimens were fractured with three 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 than documented in detail in a manner that allowed the analyst to inter-compare the fracture patterns. 41 figures; 10 tables; 28 references; and appended fracture images, high speed fracture video, testing device design, and timing system
Main Term(s): Forensics/Forensic Sciences
Index Term(s): Evidence identification and analysis ; Glass analysis ; Investigative techniques ; NIJ final report ; NIJ grant-related documents
   
  To cite this abstract, use the following link:
https://www.ncjrs.gov/App/Publications/abstract.aspx?ID=263535

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