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DaveStupple
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Thanks Disla and SnuggleKittens for the two examples - just the sort of experiments I had in mind.
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I'll have to think on that. But thanks for the clarification. Maybe that is why I got the silly stretching in my early attempts.
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Your two points make perfect sense - the first one is less obvious to me than the second one (should have been!). I managed to get one swinging last night, but I can't get any to solve today. If I uncheck Automatic Time Steps the solver gives up wit…
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Victor & JohnM, thanks for that.
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JohnM, would the dummy thermal be run as thermal steady state using the internal solver? After this, transfer temperatures from solution to create a set of node temperatures. How to go from here to temperature dependent E? Do we need to switch to St…
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I haven't used STEP files much, but when you right-click your step file in the tree there is a Meshing Parameters option. In here you can ask for a finer mesh etc. which might help. The option for surface mesh is also here.
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OK, that didn't help. CCX can be very daunting, but if you are lucky Mecway takes care of everything and it all gets done behind the scenes. The first couple of warnings might be addressed by selecting Quasi-static and then put in a duration and tim…
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Dave, have you tried selecting CCX solver in the Analysis branch? Both types of constraint become available in the menus.
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Hi davefo, stick with it, there's a lot of knowledge on this forum, and plenty of patience. Take a look at the following as a nice example of increasing stress in a sharp corner with mesh refinement: https://mecway.com/forum/discussion/362/mesh-con…
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Matt, I think you will have to set up a contact (Loads & Constraints>New contact) between the two surfaces. I initially assumed that two mesh entities would interact as they do in the real world, and I was surprised that they just pass throug…
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OK, not sure what to suggest. If you want to share the file, I could try here to do the same thing, see what happens.
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If you are trying to select all nodes within the circle, including the not visible ones behind the nearest ones, try turning off 'Show element surfaces'.
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Thanks for the explanation, Victor. I've managed to make this work with a simple experiment. In the original Mecway model, a force is applied, pushing a block and stretching an attached spring. The spring stretches, allowing the block to make conta…
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I will try to implement the *CHANGE SURFACE BEHAVIOUR idea to switch on a TIED contact. Do I follow it with a *SURFACE BEHAVIOUR, PRESSURE OVERCLOSURE=TIED line? I don't think I can use *TIE with the *CHANGE SUR... line, but I notice in a test model…
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Thanks Victor, that makes more sense now, I think. Each temperature change acts as and when it is imposed, and without ongoing comparison to an absolute global reference.
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Yes, my temperature idea was way off. Your idea is interesting. If I cool everything to -220, then have a localized region go to +1000, are these temperatures only relative to the reference, or are they also relative to each other? Not sure if I am…
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You're right that locking the ring into place gives the same results as moving it back to where it started (just x displacement constraint - no flange yet). Not sure how well my ideas on manipulating the temperature differences is working. Will per…
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Victor, thanks for the tips, will digest at leisure. You make a good point in your last paragraph - would seem to be valid if the pushing back to orignal displacement turns out to be more important than the heat cycle from the next step, which is …
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Victor, Changing the temperature in a table works best, I think, because using a formula means that the temperature carries on changing throughout subsequent steps, which confuses things. I think I have sidestepped the flange contact issue because …
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Wow, I'm an animation director! Sounds like an interesting challenge though. So you think the stages up to fixing into position for welding are all feasible. CCX is quite happy to do a time-resolved thermal stress? There might be an argument that …
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I have run thermal stress (brazing process with an optic-flange-ring sub-assembly cooling from hot to room temperature) on a thin wedge section and the solution returns displacement and stress. I was thinking to transfer these results into a new mo…
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Nicely explained, got it. Thanks.
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Hi Disla, This is a vacuum viewport, so airthight, and ultimately there will be a 1 bar pressure difference from one face to the other. The braze seals the edge of the optic to the metal ring, so the glass is in intimate contact with the braze. The…
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Hi Aswani, here's an older post on the subject: mecway.com/forum/discussion/404/mecway-vs-the-mainstream/p1
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Delano, I've had so much help from the people here that it's a rare treat to be able to help someone else. Note that when you view your solution there is a slider at the bottom to slide through the time steps. D
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Victor, Definitely agree that the weld region seems critical, I will definitely vary the degree of join and also round off the outer corners a little. I was relaxed about high stress round the weld because this is not a failure concern, but thinkin…
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*"ramp up the force over 0.5s"
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Hi Delano, I have never done plastic deformation, but I will try to get you going in the right direction. think you need to double click on the analysis type and choose non-linear static 3D, specify CCX and tick the quasi-static box. The time param…
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I have started off with a 2D mesh axisymmetric for this. The geometry around the braze interfaces may need to be changed, especially as this is the area most under scrutiny, though here there is not high stress in that area. The join of the weld rin…
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Noting the small displacement that you got in the empty pool, I think now that my collapsed results with the walls passing through each other may just have been a very high scale factor on the displacement (explaining why the CONTACT had no apparent…
