# tensor.i2

Syntax

f := tensor.i2(t)

Get the second stress invariant. The tensor must be of size three. This is defined as $$I_2 = {\sigma}_x*{\sigma}_y+{\sigma}_y*{\sigma}_z+{\sigma}_x*{\sigma}_z-{{\tau}_{xy}}^2-{{\tau}_{yz}}^2-{{\tau}_{xz}}^2$$ .

Returns: f - second stress invariant t - tensor