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Transonic and Supershear Crack Propagation Driven by Geometric Nonlinearities.
Mohit Pundir1, Mokhtar Adda-Bedia2, David S Kammer1
1Institute for Building Materials, <a href="https://ror.org/05a28rw58">ETH Zurich</a>, Switzerland.
Physical Review Letters
|June 15, 2024
Summary
Dynamic cracks can exceed the Rayleigh wave speed, propagating at supershear speeds. Geometric nonlinearities in materials are key to enabling these faster crack growth modes, challenging existing fracture mechanics theories.
Area of Science:
- Solid Mechanics
- Materials Science
- Dynamic Fracture
Background:
- Linear elastic fracture mechanics predicts crack growth speed is limited by Rayleigh wave speed.
- Experimental and numerical studies generally support this, but exceptions raise questions about the theory's validity.
- The reasons for discrepancies and the true limiting speed of dynamic cracks are unknown.
Purpose of the Study:
- To demonstrate that tensile (mode I) cracks can propagate faster than the Rayleigh wave speed.
- To identify the underlying mechanism enabling supershear crack propagation.
- To investigate the role of geometric nonlinearities in dynamic crack growth.
Main Methods:
- Theoretical analysis of dynamic crack propagation.
- Incorporation of geometric nonlinearities into fracture mechanics models.
- Numerical simulations of crack behavior under tensile loading.
Main Results:
- Tensile cracks can propagate at speeds exceeding the Rayleigh wave speed (supershear speeds).
- Geometric nonlinearities are sufficient to enable supershear crack propagation modes.
- These nonlinearities alter the crack-tip singularity, affecting crack-tip opening displacements and energy flow.
Conclusions:
- The Rayleigh wave speed is not a universal limit for dynamic crack growth.
- Geometric nonlinearities play a crucial role in enabling supershear crack propagation.
- Understanding these nonlinear effects is essential for accurate modeling of dynamic fracture.
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