Image icon  Parabolic beach marks on a polystyrene fracture surface

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Description: The fracture surfaces are generally very sharp and angular, indicating fast, brittle fracture with little ductile tearing. Parabolic 'beach marks', can be seen where the fracture has grown at a speed comparable to the speed of sound in the material. This results in periodic, momentary arrests in the crack propagation and periodic ridges in the fracture surface as it advances. These indicate the direction in which the fracture has occurred. Inside the beach marks is a disc-shaped flat region where the initial fracture was progressing significantly faster than the speed of sound. There is also evidence of the fracture surface branching onto different planes as it progresses.
Keywords: beach marks • fracture • polymer • polystyrene (PS)
Categories: Science approaches > Deformation & failure > Fracture
Science approaches > Microstructure
Materials > Polymers & elastomers > Plastics > Thermoplastics > Polystyrene (PS)
Testing, analysis & experimentation > Metallography
Scale > Micro
Created by: DoITPoMS, University of Cambridge
J A Curran, Department of Materials Science and Metallurgy, University of Cambridge
Published by: DoITPoMS, University of Cambridge
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Date created: 03 October 2002
Date added: 21 August 2009
Resource ID: 1620