Formula used
This tool estimates plane-strain fracture toughness using linear-elastic fracture mechanics. It uses the non-dimensional crack ratio x = a/W and a geometry correction.
CT and SE(B) forms
K = (P / (B · √W)) · f(x)
P is maximum load, B is thickness, W is width, a is crack length.
SENT form
σ = P / (B · W)
K = σ · √(πa) · F(x)
F(x) is the finite-width correction for an edge crack.
When yield strength is provided, a screening check follows the size criterion: B, a, (W−a) ≥ 2.5 · (K/σy)². Passing this screen supports a plane-strain interpretation for KIC.
How to use this calculator
- Select the specimen geometry that matches your test setup.
- Enter maximum load, thickness, width, and crack length with units.
- Optionally enter yield strength to screen size validity limits.
- Press Calculate KIC to show results above the form.
- Use the CSV or PDF buttons to export the calculated report.
Example data table
| Case | Geometry | P | B | W | a | σy | Expected KIC (approx.) |
|---|---|---|---|---|---|---|---|
| 1 | CT | 12.0 kN | 10 mm | 50 mm | 25 mm | 450 MPa | ~40–45 MPa·√m |
| 2 | SE(B) | 8.5 kN | 12 mm | 60 mm | 30 mm | 550 MPa | ~30–38 MPa·√m |
| 3 | SENT | 6.0 kN | 8 mm | 40 mm | 12 mm | 400 MPa | ~20–28 MPa·√m |
Example values are illustrative; your standard and fixture control final factors.