Table 1.

Expressions using the specimen's dimensions and fracture force $F$ to calculate $\sigma$, $P$, and $Q$ for various stress states.

Test	$\sigma$	$P$	$Q$
3PB	$\frac{3FL}{2b{h}^2}$	$\frac{1}{3}\sigma$	$\sigma$
ITT	$\frac{2F}{\pi dh}$	$-\frac{2}{3}\sigma$	$\sqrt{13}\sigma$
UCT	$\frac{4F}{\pi d^2}$	$-\frac{1}{3}\sigma$	$\sigma$