@peteroznewmannThank you so much for your response.nI followed your advice and (1) changed the bonded contact to frictional with 0.3 friction coefficient, and (2) changed the geometry correction to bolt thread and used pitch of 2 mm and mean pitch diameter of 34 mm. But the analysis took too long and showed ugly results. I feel I did something wrong. So could you please do these settings for me.nAnyway, I surfed a lot of results and confirmed that bolts always have the shown stress concentration regions. The more accurate model you suggest may only slightly increase the area of stress concentration, and hence, the high stresses will not reduce so much!nNow I want to know, based on the high stress values obtained, how can I decide if the threaded-hole/bolt are safe or not?nThanks and regardsn