When I make a shade smooth on the surface I created and add the subdivision surface modifier, this kind of stress occurs. I researched but couldn’t find anything to fix this. Please help me
I may be wrong, but I think that’s just how it works. You could try to increase your subdivs in order to smooth those corners so that they’ll be less visible.
Anyway, you may drop your .blend file and I’ll see what I can do.
Inset the top and then bevel the edge.
You need to smooth the math.
Click on the “stressed face” in edit mode, and click “I” to inset faves, drag the mouse while holding shift for more percision, if you want more definition you can bevel the edges, you can also add a bevel modifier on top of the subdivision modifier, note that the order matters
Subdivision doesn’t like triangles. If you inset the top, so everything around the edge is made of quads, that should fix this issue.