Hankinson's equation

Hankinson's equation is a mathematical relationship for predicting stress wave velocity as a function of grain angle in wood. Because wood is an orthotropic material, its mechanical properties are different along different axes.

:$V(alpha)\; =\; frac\{V\_0\; V\_\{90\{V\_0\; sin(alpha)^2\; +\; V\_\{90\}\; cos(alpha)^2\}$

where $V\_0$ is the velocity parallel to the grain, $V\_\{90\}$ is the velocity perpendicular to the grain and $alpha$ is the grain angle.

References

* [http://www.worldwideflood.com/ark/design_calculations/wood_strength.htm DESIGN CALCULATIONS - WOOD STRENGTH]