LOW VELOCITY SURFACE FRACTURE PATTERNS IN BRITTLE MATERIAL: A NEWLY EVIDENCED MECHANICAL INSTABILITY

Lamine Hattali (1) , Jonathan Barés (1) , Laurent Ponson (2) , Daniel Bonamy (1)

1 SPCSI - Service de Physique et de Chimie des Surfaces et Interfaces
2 EAS - Division of Engineering and Applied Science [Pasadena]

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.

Mots clés: Fracture; mechanical instability; fragmentation; brittle polymer glass

Domaines: Matériaux; Matériaux; Mécanique des matériaux [physics.class-ph]; Mécanique des matériaux [physics.class-ph]

Lamine Hattali, Jonathan Barés, Laurent Ponson, Daniel Bonamy. LOW VELOCITY SURFACE FRACTURE PATTERNS IN BRITTLE MATERIAL: A NEWLY EVIDENCED MECHANICAL INSTABILITY. Materials Science Forum, 2012, 706-709, pp.920-924. ⟨10.4028/www.scientific.net/MSF.706-709.920⟩. ⟨hal-00658231⟩