I have model in which I'm simulating basically a concrete pool filled with water. I am trying to apply an acceleration that would simulate a seismic event by using a load curve (load curve 2). I am also applying a gravity load to the model (load curve 1). What I cannot figure out is how to apply the second load curve in the x direction. Is it possible to have two different accelerations applied in two different direction? Ultimately I would like to simulate the sloshing effect of the water.
J Van Corbach
Hi J Van,
The UI does not have the ability to specify more than one gravity, so I do not suggest trying that. (The processor supports multiple gravities, but with no UI, it probably has not been maintained. And without documentation, there is no easy way to figure out how to do it through manipulating the database.)
I have two questions related to your project:
- How are you going to simulate the sloshing? Hydrodynamic elements will not simulate the motion of a fluid.
- In a static situation, I agree that changing the gravity is equivalent to the acceleration of the structure. For example, a travelling crane accelerating at 0.1 ft/sec^2 for a "really long time". So instead of accelerating the wheels at 0.1, you can hold the wheels still and apply a "gravity/acceleration" of 0.1.
But in a dynamic situation, does the gravity applied to the entire structure simulate the acceleration of a few points?
I think the solution is to use prescribe displacements (PDs) to accelerate the "fixed" nodes just like the earthquake would do. So you will apply boundary conditions in all directions except for the two directions containing the PDs. One set of PDs will follow load curve 2 in the ___ direction, and the other set of PDs will follow load curve 1 in the x direction. Be sure to follow the instructions in the documentation on the page Prescribe Displacements.
16 years experience with Simulation Mechanical