thank you for your explanations Wenlong,

I have check all the BC one by one and I have find something.

 - if I apply more than one force/remote force on the same surface, I have the waring "Two or more remote boundary conditions are sharing a common face, edge, or vertex.   This behavior can cause solver overconstraint and is not recommended, please check results carefully.  You may select the offending object and/or geometry via RMB on this warning in the Messages window." 

and "One or more MPC contact regions or remote boundary conditions may have conflicts with other applied boundary conditions or other contact or symmetry regions. This may reduce solution accuracy. Tip: You may graphically display FE Connections from the Solution Information Object for non-cyclic analysis. Refer to Troubleshooting in the Help System for more details."

if I only apply one force on the surface, then the warging message dissapear

-when I allow the displacement + the rotation on the remote displacement B (cf. my previous post) I have the warning message "Not enough constraints appear to be applied to prevent rigid body motion.  This may lead to solution warnings or errors.  Check results carefully." if I only allowed the rotation, the message dissapear.

here are my questions,

Is it a bad idea not put more than one force on a surface or can I ignore the two warning message I get ? 

because I want bike for to rotate arround the z axis and tanslate allong the x axis, should I perfrom another analysis than Static structural or not ? (I mean, can I trust the result I get ?)


sorry I am not an expert with ansys as I had only performed simple analysis before.