Stress Intensity Factors For Fracture Toughness Tests
| Compact tension specimen
The stress intensity factor at the crack tip of a compact tension specimen is where is the applied load, is the thickness of the specimen, is the crack length, and is the width of the specimen. |
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| Single edge notch bending specimen
The stress intensity factor at the crack tip of a single edge notch bending specimen is where is the applied load, is the thickness of the specimen, is the crack length, and is the width of the specimen. |
![\begin{align} K_{\rm I} & = \frac{P}{B}\sqrt{\frac{\pi}{W}}\left[16.7\left(\frac{a}{W}\right)^{1/2} - 104.7\left(\frac{a}{W}\right)^{3/2} + 369.9\left(\frac{a}{W}\right)^{5/2} \right.\\ & \qquad \left.- 573.8\left(\frac{a}{W}\right)^{7/2} + 360.5\left(\frac{a}{W}\right)^{9/2} \right] \end{align}](http://upload.wikimedia.org/math/b/d/e/bde1eb5327c6f97b5543669cecf5006f.png)
![\begin{align} K_{\rm I} & = \frac{4P}{B}\sqrt{\frac{\pi}{W}}\left[1.6\left(\frac{a}{W}\right)^{1/2} - 2.6\left(\frac{a}{W}\right)^{3/2} + 12.3\left(\frac{a}{W}\right)^{5/2} \right.\\ & \qquad \left.- 21.2\left(\frac{a}{W}\right)^{7/2} + 21.8\left(\frac{a}{W}\right)^{9/2} \right] \end{align}](http://upload.wikimedia.org/math/4/d/3/4d38a368af1d0bfb9e92dd0e599a7591.png)
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