Well then Jeff, how are you not seeing what is wrong in Ed's pictures? I will show you.These pictures are exactly from the same model, same mesh, same study. Nonlinear 65MPa pressure. Ed's way of presentation first:Then how it comes without modification:Do they look different? Why they do look different? Why didn't you see it?Presentation of the same result makes it. Why there is a full scale of stress ditribution between exactly 0 - 300 MPa in Ed's pictures as that can' be true? Where are max and min labels that are showing the max stress and min stress locations? Why didn't you see it as professional modeller? Why should anyone send you model and mesh to evaluate when it is clear you don't even understand what are you looking at?
Then, I know there will rise additional questions. If this is true, why it didn't rupture when Marko stressed it up to 720bars? Look at the picture. There is more material around where stress doesn't rise over ultimate stregth. But it did so in one local area. And 2024 is known to be corrosion sensitive material as well as 7075. Stress of pressure plus some additional mechanical force due to dropping the gun, pressing it towards the table, bending it somehow etc will form more external forces. It is not enough that pressure vessel can withstad only pressure related forces, it needs to withstand everyting else as well that can reasonably focus on it. Corrosion, material yeild strength cossing and time can do bad result. I'm not stating this is the reason of mentioned burst but anyway, there is considerable high risk area in this design and we all can see where it is no matter how it is modelled.
Bruce, could you post a picture of your mesh in the corner region. Your early pictures looked like they had a fairly uniform element size. Looking at the Freecad documentation, it looks like they have some capability to create a refined mesh in certain locations. (example from their documentation attached).
FYI, that model of mine has bottom corner radus 0.4 like usual U-drill inserts. I think it is pretty much the same as yours.
Quote from: TPL on May 09, 2023, 04:59:32 PMFYI, that model of mine has bottom corner radus 0.4 like usual U-drill inserts. I think it is pretty much the same as yours.Also like typical boring bar CCGT aluminum inserts. I'm using 0.4mm in the model.
Quote from: WobblyHand on May 09, 2023, 06:08:26 PMQuote from: TPL on May 09, 2023, 04:59:32 PMFYI, that model of mine has bottom corner radus 0.4 like usual U-drill inserts. I think it is pretty much the same as yours.Also like typical boring bar CCGT aluminum inserts. I'm using 0.4mm in the model.I am amazed you guys have to guess at this radius. I scanned the almost 30 page thread on this failure on the other forum and was surprised that some basic information was not provided. This radius spec should be clearly stated on the production drawing. I don't own this gun so it is academic for me. If I did, I would not be happy.
Well, when your product had a catastrophic, safety related failure, and a lot of your reputation is by word of mouth on forums, Some information may be needed. No need to release the drawings, just clearly state what the number is, since it drives the safety margin.For me academic, for the community, a little less so.
That band of coarse mesh, what/where is that? The transition from fine to coarse should maintain node to node connections, is that right?
Bruce, in your model, is the left (threaded) side of the tube open so the pressure does not create any axial stress in the tube?