Yamada-Sun criterion

The Yamada-Sun criterion is a kind of Tsai criterion adapted to tape (unidirectional) materials. Its failure index is calculated as follows:

F I^{YamadaSun} = {(\frac{σ_{11}}{σ_{11}^{all}})}^{2} + {(\frac{τ_{12}}{τ_{12}^{all}})}^{2} .

The allowable $σ_{11}^{all}$ depends on the sign of $σ_{11}$ . Ply passes the failure criterion if the following condition is satisfied

{(\frac{σ_{11}}{σ_{11}^{all}})}^{2} + {(\frac{τ_{12}}{τ_{12}^{all}})}^{2} \leq 1 .

The reserve factor is calculated as follows:

R F^{YamadaSun} = \frac{1}{F o S \sqrt{F I^{YamadaSun}}},

and the strength ratio is given by:

S R^{YamadaSun} = F o S \sqrt{F I^{YamadaSun}} .

This criterion is referred to as “YamadaSun” in FeResPost.