Hello everyone,
I'm in the process of doing a simulation but it freezes almost at the beginning, despite the memory being sufficient, and I've repeated several times but same problem! (see I.J.)
Kind regards
statique.png
statique.png
Hello Firass
It smells like the "great displacement"" unmanageable in full force.
Start by removing gravity that is of no use to you in this context.
You should make an image of all the connectors because I'm pretty sure you're missing some or that they're not correct.
Global contacts are often insufficient.
The big mistake not to make is to simulate the entire machine. On three knives this is more than enough.
As I think it's shaft bending you're looking for, you can do it on a simplified model with remote loading. Like what.
All this lacks information to be able to really help you.
Kind regards
PS: In addition my machine is dead (HS motherboard) I'm expecting the new machine tomorrow afternoon. so I can't read your ASM before tomorrow or the day after tomorrow because of the license management problem when you change gear. :-(
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Hello Zozo,
Thank you for your answer
I found a result after making some modifications:
I eliminated gravity, with a contact glued to all the elements (the shaft and the knives), but I do a mesh check on the shaft because at first it tells me that there is a mesh error at the shaft level (is there a contact problem?)
It's the bending and torsion (due to the torque of the mandrels) that I'm looking for on the shaft.
And I find a maximum displacement of 0.4 mm but on a few knives at the middle of the shaft! (and not on the tree!)
For the constraint I find that I have a safety factor between 2 and 3.
Kind regards
Hello
For the mesh, try with a finer mesh (but not too much because it slows down the analysis time).
You can also define the restricted area(s) on which you want a finer mesh, this avoids too long computation times by putting a fine mesh everywhere when it is not justified.
It seems to me that we have indicated how to do this very recently.
http://www.lynkoa.com/forum/g%C3%A9n%C3%A9ralit%C3%A9s/diff%C3%A9rence-maillage-grossiermaillage-fin
Kind regards
PS: To help you, can you post your ASM (using pack and go in a ZIP) that I'm looking at (that we were looking at)
Hello
Well I'm going to put the ASM in a ZIP.
The trick is at the level of the shaft because when I defined the mesh (very thin of 4 mm) it tells me that there is a problem with the mesh on the shaft, and when I do a mesh check on the shaft I find that the problems are of origin on some faces of the shaft (such as the filleting part).
I hope that's the only problem for this error! ...
Kind regards
asm.zip
as shown in this image
Hello Firass
You have attached an IGS file while you are using Solidworks I think. IGS is unusable if you don't want to take the trouble of reconstituting everything.
Can you send the ASM file back using "pak and go" (feature found in file==> pack and go) so that I get all the parts and the ASM.
Kind regards
2 Likes
Good evening Firass
You have not attached the simulation study to your ASM, so I cannot tell you.
- What's wrong with your simulation
- I can't do a simulation by starting from scratch because I don't have any data on the efforts you will put on the knife. I don't know if there is a single effort by knives or two efforts because in my opinion since the time I have been following you in your project I think that very often two teeth will have efforts.
- In addition, you have not joined the bearings or bearings that hold the shaft
So for the moment I can't do anything.
Kind regards
1 Like
Good evening Zozo,
Okay you can find the study (but I don't agree with my result because it lacks connectors).
Good for the machine as we discussed before, it has two rows and each carries two-pronged knives
For the cutting force we have 4945N for each tooth (knowing that we have 6 teeth working at the same time for a single row; in total for the machine 12 teeth work at the same time).
For the materials, I fixed in the ASM.
I come back to the connectors, I have found all the time that there is interference in the bearings which I do not allow to obtain a good result.
Still for the simulation, if there is the interference problem every day, I can switch to the simple method as you tell me, just simulation on the shaft by a remote load, but I hope it gives me a good result.
And excuse me if there is a lack of information to move forward.
With pleasure allows you to see this topic.
PS: If you need the total assembly of the grinding part as shown in the picture above, I can send it.
Kind regards
asm.zip
Hello Firass
Your simulation runs the first time without error, BUT it is totally wrong (compared to real life) for the following reason (if I have the right file)
1°) you have made the two ends of the shaft fixed which prevents you from seeing any twist at the end of the shaft that houses the key. In other words, the torsion of the shaft, at the critical point near the key, is underestimated, which is not the purpose of the simulation.
2°) You only put the effort on 6 disks instead of 12.
You are missing rings that would be fixed (I would make them). The shaft could rotate in it with a pivot link or rather a bearing load
Second solution, it would also be possible to put the supports on the tines, but there would have to be penetration in one way or another in relation to a plane or something else to be able to see the torsion of the shaft. After that, it remains to put the forces on the key with a value in N/m with a remote load.
I don't know how you determined the strength of 4945N per entity.
Is it the Max power of the engine divided by the number of entities???
Give me the power in N/m of your motor at the output of the geared motor.
I'll try the first solution already.
Kind regards
[HS On]
Finally which module you chose in the end for your two gears, given the debate we had on the other forum)
Can you post the complete ASM with the housing and the spacers between the blades because there are one or two things (totally independent of the simulation) that caught my attention and I would like to check against these impressions
[HS /Off]
PS: We really appreciate the efforts you make to express yourself in French as a Francophone (Tunisia Friendly Country). For more precision and to reduce the ambiguities of the text, perhaps you could use Google translate as a complement.
Good evening Firass
Since I don't know which version of SW you are using, I made you a report in Word.
To make this work, I simplified the model by removing the threads that would unnecessarily force you to make a fine mesh. Once these are removed, we have a number of nodes reduced by 80% and therefore the simulation is done in less than two minutes.
I created two bearings that replace ball or roller bearings (which did not exist in your ASM) to control the torsion of the shaft. Obviously as I presented it we can see very well the bending deformation of the shaft, but it is reasonable since the max displacement is 1mm in the center.
On the other hand, it shows the consequent forces at the end opposite the engine. See the attached video (to loop in your player)
I advise you to be very careful in the choice of bearings or bearings that must be hinged if you use bearings (same if they are ball bearings). It is better to use shaft bending than to unnecessarily stress the bearings by making the shaft tip too stiff.
For the efforts, I put a fixed point on the side of the keyed groove and I put the forces as you did on the knives. I prefer this solution because it is closer to reality: the knives can thus deform the shaft in torsion as in real life.
Kind regards
asm-static_1-1.docx
2 Likes
RE me
I forgot to say it but you can see in the report that the safety coefficient is close to or above 3
Here is the video! of the URES
You have to loop the playback to see something because very few frames per second because the AVI format is particularly heavy.
There you have it, have fun (aspirin not provided) :-)
video_ures_asm_firass.avi
1 Like
Hello Zozo,
Great for this stadium!
Yes, the critical point is at the level of the key because it must be transmitted a power of 11 kw (4332 Nm maximum with 24 rpm).
I put on the 6 teeth just to check a single shaft.
For the connectors, I put the spherical roller bearings at first but it tells me that there is interference in itself that's why I eliminated.
Well, for the value of the effort (it deserves a lot of time if you call back for almost 2 months for the mechanical characteristics of the cardboard mandrel ... Aa yes when I did several researches to know the shear fracture strength. But I have esteemed it thanks to experiences already done in other universities such as Delft University of Technology.
In short, the force is the product of this value (the stress) by the sheared section (already estimated by SW to be about 774 mm²).
And that's it for the gear, it's a module of 8 (they are able to transmit with their original diameters a power greater than 11 kw so it's good)
I have the 2k18 version "so no file in future version" ;)
Finally, you will find the ASM for all grinding elements.
(the name of the total ASM is Asm)
Good look, and I forgot to thank you very much, he's really the only person (also in the other forum) who helps me with your advice, that it's practically real.
There is no simple way. there is simplification ... The simple is always the simplified. "G. BACHELARD"
Kind regards
broyeur.zip
I have the 2018 version
I'll send your file back to you so you can see all the elements that I used for the simulation.
To be fair with other people, we exchanged opinions, especially on gears.
Clearly, I'm not the only one on this forum where several people follow your problem assiduously.
See you soon
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Hello Firass
Here is the ZIP file from the simulation made for the tree.
Be careful because I have not changed the name of your files and I have been forced to add two pieces that must be deleted. I suggest you use this simulation in a separate folder.
Kind regards
asm.zip
2 Likes
Very thank you Zozo
1 Like