VX AND VZ CURVES ON FLINN DIAGRAM Flinn also gave two parameters Vx and Vz (x and z are actually superscripts) given by two equations at the bottom of the figure. Because these are tan functions, the curves can only be drawn for angles that are greater than 45 degrees; the point of origin being (1,1) for undeformed material and not (0,0). Vx=tan^1(x/y) where x=a^2(b^21) and y=a^21 Vz=tan^1(x'/y') where x'=b^2(a^21) and y'=b^21
