Critical Crack Length Calculator
How long a crack becomes unstable, from fracture toughness and stress.
Steel at 200 MPa tolerates a 23 mm crack; glass at the same stress, 5 µm — that's the entire difference between 'tough' and 'brittle' in one number. Inspect at intervals < a_c growth time.
Formula
Critical Crack Length Calculator is a free critical crack for design engineers, metallurgists and QA inspectors — instant, accurate and 100% client-side, with the governing formula and reference shown next to the result so the number can be defended, not just quoted.
About Critical Crack Length Calculator
How long a crack becomes unstable, from fracture toughness and stress. The calculation implements a_c = (K_IC/Y·σ)²/π (Griffith/Irwin — Anderson, Fracture Mechanics). Steel at 200 MPa tolerates a 23 mm crack; glass at the same stress, 5 µm — that's the entire difference between 'tough' and 'brittle' in one number. Inspect at intervals < a_c growth time.
How to use Critical Crack Length Calculator
- 1Enter Fracture toughness K_IC in MPa√m (Mild steel 100+ · Q&T steel 60–120 · 7075-Al 24 · glass 0.8).
- 2Enter Applied stress in MPa.
- 3Enter Geometry factor Y (Edge crack 1.12 · centre crack 1.0).
- 4Read Critical crack length instantly — no submit button needed.
- 5Need US units? Flip the SI/Imperial toggle and every field converts.
Why use Critical Crack Length Calculator?
- ✓Implements the standard formula — a_c = (K_IC/Y·σ)²/π
- ✓Reference cited on-page: Griffith/Irwin — Anderson, Fracture Mechanics
- ✓One-click SI ⇄ Imperial toggle — values convert in place, physics stays in SI
- ✓Live worked example: the substitution recomputes from your numbers
- ✓Runs entirely in your browser — nothing uploaded, free forever
Frequently asked questions
What formula does the Critical Crack Length Calculator use?+
It computes a_c = (K_IC/Y·σ)²/π, per Griffith/Irwin — Anderson, Fracture Mechanics. The formula is displayed under the result along with a worked example substituted with your own inputs.
What should I keep in mind when using this calculator?+
Steel at 200 MPa tolerates a 23 mm crack; glass at the same stress, 5 µm — that's the entire difference between 'tough' and 'brittle' in one number. Inspect at intervals < a_c growth time.
Where do the material property defaults come from?+
Defaults are standard handbook values (ASM, manufacturer datasheets, the cited standard). Always substitute certified values from your material's test certificate for critical work.
Is the Critical Crack Length Calculator free to use?+
Yes — completely free, no sign-up, no limits. It runs client-side in your browser, so inputs stay private and results are instant even on slow connections.
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