Motionsolve, is it always possible to see the collision in a contact?

Antonio Tommasuolo

Hi,
I'm currently working for the first time in motionsolve, in my model I need to define a contact but I'm not sure of the collision I can expect from this.
In details, I've defined the model as shown in the following picture:

where the components 1,2 and 3 are free to rotate around a shaft in the middle (red dot). I've defined a contact between the two green part as shown in the following:

And applied a motion (as a velocity) in the joint in the middle:

 

In this way I obtain the expected motion from the system but there is complete penetration of the two green bodies (where I defined the contact).
I think the contact is correctly detected because I have the contact pressure and other informations in the results, but there is no impact.

I have the expected impact (and stop of the body) if I define a gravity accelleration on Z. So I think that the problem is for the motion that doesn't stop when impact happens?  (I tried also with a force and get the same results)

Praful

Hello @Antonio Tommasuolo 

You did not share the CAD file that the graphics are using in the mdl, so I could not take a closer look. However, I see there is a motion on the revolute joint. Motion is a constraint and it will force the body to rotate further and penetrate into the contacting part.

You might want to use a different way to make the part rotate (a torque or a torsional spring) so that the contact behaves as expected.

Regards

praful

Praful

Hello @Antonio Tommasuolo 

You did not share the CAD file that the graphics are using in the mdl, so I could not take a closer look. However, I see there is a motion on the revolute joint. Motion is a constraint and it will force the body to rotate further and penetrate into the contacting part.

You might want to use a different way to make the part rotate (a torque or a torsional spring) so that the contact behaves as expected.

Regards

praful

Antonio Tommasuolo

Hi @Praful Prabhu,

thank you for the fast answer! I've imported the graphics from an hm file you will find it attached.

I'v tried also with a torque the sahft now, but got the same result. The mdl attached is this the model with the torque. Maybe the problem is in the point of application of the torque now.

If the files are not enough to visualize the model please give me more instruction of what file is needed.

Edit: I checked the constrains, the problem was in the definition of the shaft as a ground body, I suppose that for let the middle table coming back after impact I need a free relative movement between the shaft and the table.
Again thank you for the answer.

I have one last question, can you show me the correct way to impose the constrains on the shaft?

Logically I will use 3 revolute joint (one for each table), but it isn't working for me. The desidered motion is upper and lower table not moving and middle table freely rotating (until impact).

Christopher_Fadanelli

Antonio Tommasuolo said:

Hi @Praful Prabhu,

thank you for the fast answer! I've imported the graphics from an hm file you will find it attached.

I'v tried also with a torque the sahft now, but got the same result. The mdl attached is this the model with the torque. Maybe the problem is in the point of application of the torque now.

If the files are not enough to visualize the model please give me more instruction of what file is needed.

Edit: I checked the constrains, the problem was in the definition of the shaft as a ground body, I suppose that for let the middle table coming back after impact I need a free relative movement between the shaft and the table.
Again thank you for the answer.

I have one last question, can you show me the correct way to impose the constrains on the shaft?

Logically I will use 3 revolute joint (one for each table), but it isn't working for me. The desidered motion is upper and lower table not moving and middle table freely rotating (until impact).

Hello @Antonio Tommasuolo ,

 

Could you possibly share the model as an archive model? When sharing models, external entities (CAD graphics, flexbodies, csv files, etc) are saved in the .md path based. To do so go to File > Export > Model> Archive Model and share the zipped folder. 

I did try to reassign the graphics, but I am missing the dark green box in your original picture.

I also noticed that the motion and torque were both activated. Did you try deactivating the motion and then running the simulation? To deactivate a entity, right click the entity and select deactivate in the menu.

 

I am also attaching a link to our Introduction To MotionView/MotionSolve that goes over the basic for creating a model in MotionView.

Hope this helps!

Christopher Fadanelli

Antonio Tommasuolo

Hi @Christopher Fadanelli,

I didn't notice the error, now is all working fine! Thank you also for the informations about how share the model.

 

Have a good day!

Antonio Tommasuolo