Learning Forum

[ryan.spence]

I'm doing a static structural analysis on a pipe support with a number of bolts. I have deafeatured the bolts so they are cylinders to aid with meshing. Each of the bolts are M8 and have a 6180N pretension added to them. The results show a peak stress on the underside of a bolt head, where it contacts a washer using a frictional contact type (coefficient = 0.2). This stress seems to only be surface level and is concentrated at one node. I don't believe this is a singularity as when I refined the mesh on the bolt the results stayed roughly the same.

I have two questions:

1. Is it safe to ignore these surface level stresses if the average stress in the body of the bolt is accceptable?
2. If the bolt pre-tension causes high stress in the bolt body exceeding the yield strength, does this mean my pre-tension value is too high for the bolt size or can this also be ignored?

Thanks!

[danielshaw]

It appears that the model has some local stress singularities.  You might want to watch this video to better understand them.

https://www.youtube.com/watch?v=mkr0vp_u1KM