The near-tip field at high crack velocities

✍ Scribed by K. B. Broberg

• Publisher: Springer Netherlands
• Year: 1989
• Tongue: English
• Weight: 666 KB
• Volume: 39
• Category: Article
• ISSN: 1573-2673
• DOI: 10.1007/bf00047435

✦ Synopsis

Several velocity regions, distinctly different as regards crack edge propagation characteristics, can be distinguished. The simplest case is mode III with only the subsonic and the supersonic regions. For modes 1 and II four different regions can be recognized. When analyzing the near-tip field at leading and trailing edges it is found that some velocity regions are forbidden. The most important field characteristic is the energy flow to or from the edge. A clear difference exists between modes I and II: for mode I the whole region between Rayleigh and irrotational wave velocities is forbidden, for mode II only the subsonic super-Rayleigh region.

In attempts to provoke crack edge propagation at a velocity in a forbidden region, the result appears to be edge propagation at velocities alternating between velocities in non-forbidden regions, above and below the attempted velocity.

A study of the stresses ahead of the edge region of a mode II crack expanding in both directions indicates that the edge might accelerate (by a jump) spontaneously from a sub-Rayleigh to an intersonic velocity.