User has to enter the moduli of elasticity **E**_{x} and **E**_{y} of the material in x-axis and y-axis directions, shear modulus **G**_{xy} , as well as Poisson’s ratio **ν**_{yx}. The second Poisson’s ratio is calculated using formula *ν*_{xy}=ν_{yx}E_{x} / E_{y}. We also check the restriction *ν*_{xy}ν_{yx} < 1 for orthotropic material and *0≤ ν*_{xy} ≤ 0.5 for isotropic material before the calculation. In the case of isotropic material the field for shear modulus can be left blank. Corresponding value will be calculated by formula *G*_{xy}=E_{x} /(1+ ν_{yx})/2 .
Please use the same system of units throughout the calculation. For instance,
if you use force unit N and length unit m, the unit of elasticity modulus should be N/m^{2}.
Obviously, the result of calculation will have the same unit system in this case:
uniformly distributed load – N/m.

The program calculates the critical value of load combination, which is represented both graphically and by formulas.