## General Mechanical

Topics relate to Mechanical Enterprise, Motion, Additive Print and more

#### Determination of the dynamic center of gravity of tractor/Rigid Dynamic

• Hanwen_Elmo
Subscriber
Hello all,ni'm now working on my master thesis about stability system for tractor (e.g. avoid pitching). Here is a task in Ansys WB/Rigid Dynamic to determine the center of mass of the tractor. The tractor is moving and the left front wheel and also the left rear wheel are lifted by a ramp in such a way that the center of mass of the vehicle moves to the right edge of the stable triangle formed by the two rear wheels and the self-aligning bearing of the front axle.nThe problem is, in Mechanical unfortunately I could not find the function to determine dynamic center of mass. Can someone maybe give me a tip what to do so that I can determine the center of mass? APDL also fits for me.nBest RegardsnHanwe
• 1shan
Ansys Employee
,nInsert a position probe(solution>insert>probe>position) and select the body whose CG you wish to track over the simulation. nRegards,nIshan.n
• Hanwen_Elmo
Subscriber

Hello @Hanwen_Elmo,Insert a position probe(solution>insert>probe>position) and select the body whose CG you wish to track over the simulation. Regards,Ishan.https://forum.ansys.com/discussion/comment/107172#Comment_107172

Hi Ishan @1shan, , thanks for your answer. I inserted a probe for Position and used 'Box select' to choose my tractor but seemed like there were some problems in deteils:nThis tractor has many parts, the method you mentioned works on when one part of tractor selected. So how could I do?nRegradsnHanwenn
• 1shan
Ansys Employee
,nCould you try creating a named selection with all the bodies in it and the scoping the position to this named selection.nRegards,nIshan. n
• Hanwen_Elmo
Subscriber
nnthanks for your kind tips. Unfortunately there is no option for named selection in probe position.nnRegardsnnHanwenn
• 1shan
Ansys Employee
,nYou could create a coordinate system. (right click coordinate system select all 44 bodies) This creates a coordinate system at their CG. Then scope the position probe to this coordinate system. You could also try to combine all 44 bodies into a single multibody part using design modeler(https://forum.ansys.com/discussion/4116/how-to-find-center-of-gravity-and-moment-of-inertia) but you might loose the scoping attachments, so I think the coordinate system scoping method should be better.nRegards,nIshann
• Hanwen_Elmo
Subscriber
nthanks for your kind help!nas you said i created a new Coordinate system including 44 bodies and scoped that position probe to this system.nBut after solving there was an yellow flash icon (Error: Probe failed to intersect your model) and there wasn't any information why it could not be solved. I also tried to combine all bodies into one multi-body but there were so many connection problems und was so comlicated.nBut i still want to say thank you. If you have more ideas or tips please tell me!nRegardsnHanwenn