There seems to be a mistake in the PressureDependMultiYield Material and PressureIndependMultiYield Material documentation.
The stress-strain backbone curve is defined as: Tau=G*gamma/ (1+(gamma/gref)*(pref/p)^d) ,
I think it should be: Tau=G*gamma/ (1+gamma/gref) * (pref/p)^d
Error in PressureDependMultiYield documentation
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