Constrain Rigid Body Trajectory

Altair Forum User

Hello all,

 

I have a rigid body impacting a device. It is a frontal impact and the rigid body is not supposed to turn. However, as I input initial velocity (on master node only), the rigid body behaves on its own during simulation. So I constrained all rigid body nodes in X and Z directions (impact on Y direction). But I get a warning:

 

WARNING ID :          312
 ** INCOMPATIBLE KINEMATIC CONDITIONS IN MODEL
DESCRIPTION :  
    2886 INCOMPATIBLE KINEMATIC CONDITIONS IN MODEL

 

1. I don't think my kinematic conditions are problematic.

2. My simulation works but the rigid body still turns on itself and does not respect the bcs condition input

 

How can I solve this problem ? 

 

Thank you in advance,

Alice

gopal_rathore

The initial velocity is applied in y direction?

Also have you used ICoG for rbody, it will make master node as CG of the impactor so the velocity will act on cg of the impactor and will not cause any rotational motion.Also if you are simulating a straight line motion of impactor, you can also constrain other degrees of freedom.

Altair Forum User

Hi Alice,

Please recheck your model and ensure that the nodes are not over constrained and also the constraints are not violating the loads applied. For the rigid body master node, constrain all degrees of freedom except Y and try running.

If the issue persist, please share the model file through the secure dropbox link, so that we can review the model.

Altair Forum User

Hi,

 

Thank you for both your replies.

 

I changed ICoG from 0 to 3 and I constrained only the master node (and not all the slaves nodes of the rigid body) and it works great now.

 

Thank you a lot for the quick help !

Alice