Hi again. I've got high very high stress under the head of the bolt (in my case). I think it because the thread doesn't consider in the analysis and all force goes to the zone under the bolt head. In reality, the first round of thread takes the main load of pretension. How go you think if I model a real thread what contact should be used between hole and bolt thread?
Actually, it will still deform, but stress plots you will get will be way higher and inaccurate. you can use 2 axy sym constraints and apply differential pressure on the pipes to simulate more accurately. But most practical Industrial analysis we do, only involves determining the thickness of special flanges that are not covered by the codes.. There was one occasion when the customer put a class 150 flange for a pipe that operates at 22 bar pressure. Since it violated the codes, the inspection body left him two choices, either cut and re weld a class 300 flange or come up with FEA analysis report that shows class 150 flange can handle 22 bar pressure without falling apart. However, the flange will be replaced when the unit shuts down for annual maintenance.
Because it's simulating a section of a complete pipe flange. When pressure is applied all "sections" will expand together. The sliding support simulates the expansion of the pipe.
Really the most accurate analysis upon the bolt pretension problem I've ever seen. Thanks so much for this greatly useful content
Well done. thanks for video!
Very Useful! Thank you!
usefull video, well explained.
Glad it was helpful!
Thank you
Bro can you share link of cad model?
Hi again. I've got high very high stress under the head of the bolt (in my case). I think it because the thread doesn't consider in the analysis and all force goes to the zone under the bolt head. In reality, the first round of thread takes the main load of pretension. How go you think if I model a real thread what contact should be used between hole and bolt thread?
maybe the contact of your bolthead and your flange face is bonded, i think
Hi. Why didn't you use fixed support contact for those three sides instead?
if you used fixed support on all three sides, the flanges will not deformate
Actually, it will still deform, but stress plots you will get will be way higher and inaccurate. you can use 2 axy sym constraints and apply differential pressure on the pipes to simulate more accurately. But most practical Industrial analysis we do, only involves determining the thickness of special flanges that are not covered by the codes.. There was one occasion when the customer put a class 150 flange for a pipe that operates at 22 bar pressure. Since it violated the codes, the inspection body left him two choices, either cut and re weld a class 300 flange or come up with FEA analysis report that shows class 150 flange can handle 22 bar pressure without falling apart. However, the flange will be replaced when the unit shuts down for annual maintenance.
Because it's simulating a section of a complete pipe flange. When pressure is applied all "sections" will expand together. The sliding support simulates the expansion of the pipe.
how would one model fatigue after pretensioning. the pretension should be fixed but in ansys it reverses using fatigue tool
Hopefully it doesn't. You shouldn't be exceeding the elastic limit of the material.