Learning Forum

[Maryam Tabbakhh]

Dear ido and Ushnish,

 

I have an important question about this topic. I want to apply the earthquake in z direction to the tank fill of water with the box floating on it like top figure. I add one more picture to show it better here. I need to first gravity initialize the box and after it reached equilibrium, I am going to apply earthquake just in Z direction. It is basically two step. Step one, from 0 to 5 second, I just apply graviry through a inclined curve and then apply earquake at 5 second ( the acceleration that I provided starts after 5 second). My problem is that I need the base of the tank to be fixed in z direction in order to gravity initiation, but for the next step that I want to apply acceleration in z direction, I need that DOF in z direction to be free. If I fix DOF in z direction, my tank doesn't more in z direction when earthquake applies but the first step (gravity initialization) reaches equilibrium and the problem with having the DOF in z direction free, it doesn't converge in the gravity initialization and box starts to rotate. Do you have any solution for me? I did the same thing for Y direction and the results were successful because for applying earthquake in y direction, I don't need to free the DOF in z direction free and I could get reasonable response. Appreciate any suggestions. 

Thanks a lot

Maryam