Has anyone use different versions of LS-DYNA to solve a problem?
I have used LS-DYNA R7.0 to model an underground pipe filled with water, and I recently model it with R11.0. I have noticed that there is a noticeable difference. I have narrowed down the difference, and it seems to be either in CONTRAINT_LAGRANGE_IN_SOLID or in modelling water using EOS_GRUNEISEN.
I wonder if anyone else encountered such a difference, and if you did, why is that? is it more accurate?
LSTC are continuously updating LS-Dyna and yes, a lot of times the changes can affect results substantially. It all depends on what was changed between your versions. v7.0 to 11.0 is quite a jump so there is a possiblity that a lot of things changed which will make isolating the difference for your simulation much more difficult.
I've never experienced a change like you are mentioning with these cards. I would suggest creating a simplified simulation to test these things between the two versions so that you can see how the versions affect the results more clearly. You can also contact LSTC about any concerns or request how those cards have been altered.