Learning Forum

[oliver.li]

I am doing a bolt & nut simulation with 3D model. It's a M4 bolt & nut and the Bolt pretension is 3167N.

For the thread contact areas， I am using a Bolt Thread of Contact geometry correction @ frictional contact, everything goes well except the Equivalent stress at the Bolt thread contact area, the Finer the mesh, the bigger the Equivalent stress at the Bolt thread contact area. When I refine the mesh to 0.2mm sizing, the Maximum Equivalent stress is 1109 MPa, it is quite unreasonable, can any one tell me why? Thanks in advance.

 

[harshithmc2]

Not sure if this is right, but it appears only at a single node and since the mesh size is so small, the stress also rises up. This is mainly occurs due to the very fine mesh size. This video by Ansys explains why it occurs

[mohan.urs]

Hey,

The mesh on the nut seems to be too coarse when comapred to the bolt. This results in less number of contacting elements between the bolt and the nut. Can you make the mesh on nut more comparable to the bolt and check if there is any improvement in stress distribution.
Also what is the goal of your study - is it to study the stresses generated on the bolt threads ??
Can you also check what the stress levels are a little away from that zone..

Regards,
Mohan Urs