Learning Forum

[Alaa Ahmed]

I am trying to simulate the response of a three-body system that all of them are affecting the motion of each other. The system consists of two vertical plates hinged from one end to a horizontal plate. The system is placed in water where 1m of the vertical plates are above water while the rest of the sytsem is submerged in water.

I have 3 UDFs for the three bodies where I have the mass properties and using the Six DOF to simulate their interaction with the waves in the water. To be able to simulate the coupling and the effect of each body on the other I checked the relative motion option box when creating the dynamic mesh zone for the two vertical plates with choosing the horizontl plate as the relative zone. I couldn't do the same for the horizontal one as we can't choose two zones and if I choose one only the calculation doesn't start. I kept it checked for the vertical plates only and started the calculation, I kept the vertical plates stationary and the horizontal one moving in the x-direction only. In the UDF of the horizontal plate, I have an external force in the x-direction. The results came out that the three bodies have the same cg displacment amplitude which is expected, but the amplitude is the same as when the platform is by itself without mounting the vertical plates on it. It seems like the horizontal plate is not affected by the vertical ones. I have attached some screenshots to help in understanding the problem.

Could you please help me in modeling the relative motion between the three bodies?

 

   

 

 

[Prashanth]

Hello!

Did you make sure to create the relative rigid body zone before creating a rigid body that is dependent on that zone?

[Alaa Ahmed]

Could you please elaborate more on what you mean by creating a relative zone?

I have created three zones for the three bodies, then I need to couple them together.

If there is an example or video to show what you mean that would be helpful.