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How Fast Cracks in Brittle Solids Choose Their Path
Lital Rozen-Levy1, John M Kolinski2, Gil Cohen1
1The Racah Institute of Physics, The Hebrew University of Jerusalem, Givat Ram, Jerusalem 91904, Israel.
Physical Review Letters
|November 6, 2020
Summary
Understanding crack paths in brittle materials remains a challenge. This study reveals that crack propagation is governed by maximal strain energy density, even in perturbed conditions, offering new control possibilities.
Area of Science:
- Solid Mechanics
- Materials Science
- Fracture Mechanics
Background:
- While crack propagation in homogeneous brittle solids is understood, the determination of crack paths in perturbed conditions is not.
- Running cracks can be deflected by material defects or intrinsic instabilities.
Purpose of the Study:
- To experimentally investigate the path determination of strongly perturbed cracks in brittle materials.
- To understand the influence of defects and instabilities on crack propagation dynamics.
Main Methods:
- Experimental study of cracks propagating at high velocities (10%-95% of limiting velocity) in a brittle material.
- Dense high-speed measurements of strain fields surrounding crack tips.
Main Results:
- Crack paths are governed by the direction of maximal strain energy density, even when near-tip fields are highly disrupted.
- Deflection is observed due to interactions with sparsely implanted defects and intrinsic oscillatory instabilities.
Conclusions:
- Maximal strain energy density is the key factor determining crack paths in perturbed brittle solids.
- This finding provides a basis for controlling or guiding running cracks.
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