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- เผยแพร่เมื่อ 15 ต.ค. 2023
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In this video, I showcase a PIN Connection Case Study. We will not only analyze the Nonlinear FEA outcomes but also compare those with the capacities calculated according to the code EN 1993-1-8.
Please enjoy! - บันเทิง
We often neglect how powerful plastic strain plots can be.
Indeed, I feel that most of FEA revolves around von Mises plots (for better or worse).
Superb explanation. Would love to have had this kind of professors at my university. Everybody just grasps ober the topic, like not even knowing it that deep. Sad.
Thanks Mate! I'm glad that you like this :)
Thank you for the valuable tips.
Of course Mate, I'm glad that you like the video :)
Thank you again Sir Lukasz for the result of your non linear analysis. It clearly shows 2 shear plane occurs per each Lug. This is very useful since there is no code gives clear guidelines whether 2 plane shear or single plane shear will be applied on pin-connected member. Therefore for this configuration where there is axial uniform load is applied 2 plane shear will be applicable..But what about if the load is not uniform when there is a out of plane load, especially occurs in Lifting Lugs where the sling with angle attached to the shackle, then pin shackle connected to the pin hole.. In this case load is not uniform, then single plane shear maybe more applicable for shearing stress?
Thanks for great session
I'm glad that you liked it Mate :)
Great video
Thank you! I'm glad that you like it :)
Hi, Lukasz, this is one great explanation. I have one question with regardless to plastic theory. I am reading your enterfea blog, and I know that you are using Rfem software, and I want to compare Von Misses plasticity implemented in Rfem and for example Adina or Abaqus . I am not talking about large strain plasticity (probably this is not implemented in rfem). In Abaqus or Adina Von Misses plasticity is followed by FLOW RULE and YIELD FUNCTION, but, what about rfem is it the same math or something else, maybe simpler?
Great FEA session and insights into Non-Linear analysis using equilibrium paths and indicative failure modes. I just have a question: Where did you query the equilibrium paths for all the 3 cases ? Since you divide the max load capacity by the no. of shear planes (2 in pin shear case, 4 in plates' shear failure) and the no. of parts involved (2 in case of plates' contact failure), it's unclear to me how you select the query part/geometry/node/element/surface of interest or if you just selected the entire model (2 plates + pin) and then compare equivalently with the codes? Thanks for your time and answers!
Hey! Thanks for your kind words, I'm glad that you like the video :)
I used the total vertical deformation of the top of the upper part (that I pulled) against the force I needed to pull it with. Hope this helps!
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Thank you for this very informative video. Which material behaviour did you use ( Bilinear,elastic-plastic or other) ?
I used an elastic - perfectly plastic material. In this application I didn't really needed anything more fancy, especially with typical "structural steel" being used, with a nice plastic plateau :)
Thank you so much Sir Lukasz for sharing. This part of structure plays important role especially for heavy equipment and module lifting. Please allow me to ask my query.
1. What is the maximum von mises stress for Case-1 and Case-2.
2. Do we need to perform mesh convergence in this type. Since there is a changes in geometry like hole, there may be need to check mesh convergence?
3. Is plastic strain contour map you show for shear check can display from FEMAP, in addition to maximum von mises stress contour map? Just curious since I try to find out using STAAD, but i afraid there is no such thing plastic strain contour map. Thank you again for your sharing. Actually I almost near and close to decide to take masterclass but my remaining issue is if my software that I use is not capable to perform good output Non Linear Analysis, then it will be hard for me to follow all things. I am checking now the capability of STAAD in non linear analysis.
Hey Jess! Let me answer your questions one by one:
1. There is no "von Mises Stress Limit". In material nonlinear analysis, this doesn't really apply in structural steel, as for elastic-perfectly plastic material the max stress you will get is yield stress. It's the strains that should be limited - various codes use various options, but usually, the plastic strain limit is around 3-5%.
2. If you are not sure about mesh quality it's always good to make mesh convergence. I simply knew, that my mesh was good enough for the task, so I didn't perform a mesh convergence... but if you are in doubt - it's always better to check :)
3. Plastic Strain requires nonlinear material analysis. If this setting was turned off (or your software can't handle it) you won't be able to display it. If I would run a linear material in Femap, I wouldn't have this plot either, since plastic strains are clearly an outcome from nonlinear material analysis :)
In the end, I'm really glad that you are interested in my nonlinear FEA course - this is so nice to hear ;)
Thanks a lot Sir Lukasz for your helpful input. That helps a lot.
@@arocenajesussusmerano174 I'm glad that I could help you Mate!
Hello! I like a lot the way how you explain everything! :) May I ask what is the name of the software you used for the FEA ?
I'm mostly using Femap with NX Nastran
Hej Łukasz. Could you start your videos with a brief description of boundary conditions applied? As for this example - when there are nonlinear contacts involved and there's seemingly nothing that stabilises the model (model is not fully constrained, contacts are not 'bonded') is it 100% reqquired to explicitly use "soft springs" / "rigid body motion" or whatever this may be called in other software? Or based on contact types do some packages like ANSYS or FEMAP somehow resolve it in a different way or automatically? I'm asking since an analyst in my company (ansys) said he doesn't have to apply soft springs, ansys just moves on on its way and frictional contacts stabilise the model. In theory empty places on stiffness diagonal are disallowed numerically...
Hey Mate! Thank you for the suggestion. I understand the need, and I will definitely make some videos about boundary conditions, but I don't want to make my videos "too long" so talking about everything in every video won't work I think :(
To answer your question, I think I used soft springs in the model to stabilize the pin. You could also use the symmetry of the model to do that, but I don't like how the outcomes look (and it's important for the video) so I made a full model.
Cheers!
@@Enterfea Symmetry wouldn't work in the vertical direction. I understand and actually applaude the need to keep things consise and to the point, but in the world of FEA boundary conditions are everything. You can't really judge the resulsts without knowing them and as this is a technical and study matrial I'm 100% sure no one would argue the videos are 20 seconds longer than they should, no need to always get into deep details :) By the way - great work as always, I'm nagging my boss to buy me your training course and I was happy to see some exmples of your analysis in Dominique Madier's book! Good read, just started it.
@@eartheartbaratheon791 Yea, this is always a thin line on what to talk about and what to ignore - but I totally see your point!
Tension failure also for lugs with small widths
Sure, but I would have to still change the geometry to get that (assuming that I understand what you mean). If I have an "equal" amount of material on the "top" and on the "sides" of the pin (in the plate of course) then shear will always "win" simply because the area is the same, and shear capacity is divided by square root of 3. Still, you are absolutely right - if I had more material on the "shear area" and less on the sides, tension failure would be a thing - while I didn't want to make that case in the model I should have mentioned that in the video! Thanks for pointing this out!
Good pronunciation, escpecially RRRR
Hello! :) Please, could you tell me, how to make this example in SolidWorks ? I need help with the fixtures, connections. I mean, what is the contact interaction between the components and which degrees of freedom are removed to be model stable.
Thank you, Lukasz. What material behavior model did you use? (Bilinear or multilinear)
It was a bi-linear material model :)
I thought with a bilinear model, it is impossible to get a chart of the load capacity since the chart will always grow.
@@Archrussia it can fall down if you have a nonlinear geometry implemented in your model as well :)
in minutes 8.10 ; what material model do you use to achieve negative slope like that? Why is there no strain hardening phase indicated in the graph?
This is actually an impact of nonlinear geometry :) If it would be only nonlinear material, it would be indeed horizontal (more or less). Hope this helps!
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Waste of time