My custom result must be based on a condition applied to scaled Von Mises stresses. If these scaled Von Mises stresses are higher than a threshold (e.g. 2.5), the custom result will follow a specific formulae (e.g. 10^(x/2.5)). If they are lower, the custom result will be got applying another formulae (e.g. 10^(7.5log10(x100)-x*5)).
Please be aware that this formulae are dummy.