I am running ProPoMax in mm ton sec units, and want to add hyper elastic properties using the ARRUDA-BOYCE model. This will have to be entered manually which isn’t a problem but I suspect the units I started with are far off as the model won’t converge (it runs fine without hyper elastic properties and for a while with hooke before blowing up).

Right, it’s hard to find information about this since units are often omitted, especially for D. But it seems that 1/MPa is most commonly used: html.scirp.org/file/_3-2190113_1.htm

Just like it is the case with incompressibility parameter for other hyperelasticity models.

According to Abaqus documentation, K_0 = 2 / D where K_0 is the initial bulk modulus. Wikipedia claims that D_1 = K / 2 where K is the bulk modulus but equation they use includes D_1*(((J^2-1)/2)-ln(J)) while Abaqus uses 1/D*(((J^2-1)/2)-ln(J)). This seems to explain the inconsistency.