Low Velocity Surface Fracture Patterns in Brittle Material: A Newly Evidenced Mechanical Instability

Abstract:

The occurrence of various instabilities at very high speed is well known to occur in brittle fracture and significant advances have recently been obtained in the understanding of their origin. On the other hand, low speed brittle crack propagation under pure tension loading (mode I) is usually thought to yield smooth crack surfaces. The experimental investigation reported here questions this statement. Steady cracks were driven in brittle glassy polymers (PolyMethyl Methacrylate - PMMA) using a wedge-splitting geometry over a wide range of low velocities (10^-9-10^-1 m/s). Three distinct patterns can be observed on the post-mortem fracture surfaces as crack velocity decreases: perfectly smooth at the highest speed, regularly fragmented at intermediate speed and macroscopically rough at the lowest speed. The transition between the two latter is reminiscent of chaotic transition. ^[e-mail], ^[e-mail], ^[e-mail], ^[e-mail],

• Periodical: Materials Science Forum (Volumes 706-709)
• Pages: 920-924
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.706-709.920
• Online since: January 2012
• Authors: M.L. Hattali, J. Barés, L. Ponson, D. Bonamy
• Keywords: Brittle Polymer Glass, Fracture, Fragmentation, Mechanical Instability

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