hello everyone.

I've some issues with a project i'm working on. the task is to statically simulate a symmetrical hitch trailer bar system.

So basically in aim to obtain accurate results i managed to defeature the unnecessary features also i considered only half model to ease and fasten the results without hindering and weakening my computer resources. i managed to use solid elements for all my parts ( results are demonstrated below)

  so more about defining my boundary conditions i have specified some fixtures as follow:

- initially a symmetrical fixture was set at the faces figuring in the symmetry plan

-  i restrained radial translations  in the bolt cylindrical holes as shown below

- i also restrained translation in the bolt head imprint on the bottom face normal to the created virtual wall (rigid, k=0.2) as shown below

for the load i considered as a first case study to apply a nose load on the top face of the coupler ball ( refer to 1st pic)

- for the connections specification i applied frictional ( no penetration) contact to all where there is a contact and specifying 0.2 as friction coefficient (k)

-also i used physical bolt representation by specifying 80 N.m as torque preload (8.8 alloy steel)

- i kept my geometrical pin where i specified the necessary no penetration contact to the holes and to the cylindrical face of the pin (k=0.2)

- lastly for the mesh i set it as follow:

also i specified an h-adaptive mesh refinement ( in most loaded areas)

so after setting all the necessary simulation B.C's i start the study runner and directly i got the following problems

1st issue

2nd issue

3rd issue 

i'm really lost here . i hope you guys can help me to solve this issues 

If you find necessary to have access to the files please ask me so i can raise them here in the forum 

thank you.