As a beginner to soil constitutive modelling, I am learning the hypoplastic models by reading the matlab drivers. I am confused with the matlab file f_hyp.m in the model hypo_sand. I don’t understand why the right side of the equation is a “-” rather than”+” in line 52 and 71. Besides, when I change the icode from 5 to 3 in the file input_data.m, it can’t successfully run, I couldn’t figure it out. And after reading Bardet’s paper (1991), I find that it seems we exchange the place of dsigma11 and dsigma33 so that the matrix of S and E are a little different from Bardet’s paper (1991), is my guess right？
Thanks a lot！
Hi Shaoxiang, “-” rather than “+” is there just due to different sign convention (compression positive vs negative). Yes, dsigma11 is replaced by dsigma33, as Bardet used “1” vertical direction and here in the driver “3” is vertical direction. If you change icode, you also have to update DX vector. Regards David