Download the model shown in the tutorial here: feassistant.com/product/ball-and-block-ls-dyna-example-models/ Consider joining our FEA-focused community forum if you are interested in learning more! feassistant.com
I generally don't comment on tutorials, but I just cannot begin to express how useful these are and how easy it is to follow. Thank you for these awesome tutorials!
@UnpopularMechanics I have a quick question. Let's say that I want to simulate a structure made out of just steel tubes welded together in 3D space. Can I just create that structure by creating linear elements and assign beam type to it? Also, how would the results vary between beam and truss elements?
Thank you so much! I absolutely like your authentic, down to earth style. You just casually say "cookies are done". It´s sooo random, but also provides some comic relief in this very technical video.
Hi there, Thanks so much for the presentation really clear and very useful. When I set mine up I found the ball passes through the block contact? do U have any suggestions about why that maybe? I rechecked everything and even inverted master and slave but it still happens? Sure I have messed up cant see where. Also is it possible to post the .k file so we can compare? kind regards A
30:32 Could it be because the ground cannot move and consequently has to take all the force from the block..whereas the block can dissipate the force to be absorbed as internal energy..hence the lesser force spike in 'Ball to Block' as compared to 'Block to Ground'? Also i think surface area concept expects the opposite to happen..right?
Great work, thank you. Regarding the energy unit, kN-mm. One J (Joule) of energy, equals to the force of one Newton acting through one meter (Nm). To be consistent with other units, kJ (Kilo-joule) is kN-mm.
Sir, I want to apply a certain downward force from the top of the structure, then want to simulate blast effect on that loaded structure, I am succeeded by doing without load, but unable to apply force on that structure. Could you provide a hint that how to apply force/load on a certain part of the structure, I will be thankful to you.
You can do this a few ways. The easiest would be to apply a point load at the top of the structure using *Load_Node_Point where you have to select the node to apply the force and provide a force vs time load curve (LCID). You can also define a local coordinate system to apply the load in a specific direction, but you don't need to if your global coordinate system works for the direction that you want to apply the load.
Unpopular Mechanics I am doing reinforced concrete in ls prepost, how to make a model of reinforced concrete and the relationship of the bond and slip of reinforced concrete. I hope you have a video like this, appreciate it if you can
Hello, I don't know if you'll read this comment but I have come across some problems with the simulation. In LS-Run I couldn't choose to export the file in d3plot, as you showed in the video. Do you know what is wrong ?
I love your tips and content. there is a question. during selecting the contact you said it's better to choose segment set!! there are differences? or because you just want to choose top and bottom you do that?
Honestly, there are a lot of small details regarding contacts that you can modify, depending on issues that you are seeing in your model. Segment sets within a contact are more accurate for a 3D mesh than a basic part to part contact.
Thank you for the tutorial - I'm just getting into this, and it is rather daunting. I'm following your tutorial, but when I compute, it throws negative volume errors. It occurs for a single solid element. If I stiffen up the block to 0.1, I can complete the simulation, but I would enjoy seeing the jello-effect that you observe. Can you advise on how to debug this? Cheers.
I am doing an analysis of load blast on the structure and inserted the stress-strain curve graph in "DEFINE_CURVE" option for the structural response to high impact blast, but in output, I am getting relevant data such as displacement, velocity, the stress in standard units (meters, second, pascal, newton) but getting acceleration in 6th power, which is damn high, where I am failing?
Hmmm that’s strange that you are getting realistic velocity and displacement values but not acceleration. Have you tried differentiating your velocity to get acceleration to check that it’s not just a bug with prepost?
You're just amazing! Amazing content and I hope you upload more videos on LS Dyna. I've few questions. 1) How do I get the reduced keyword text file so that I can print it for reference etc. 2) How do I do a convergence study of a complex model. i.e if I need to make a mesh finer after a simulation without deleting anything. 3) Which Software you used to record these tutorials? Thanks
Thanks I really appreciate the kind words! 1) Do you mean how do you collapse the keyword .k files so that only the *Keywords are showing? I use a text editor called CAXedit that makes it easy but there are probably some plugins for editors like textpad and notepad++ that can do something similar. 2) This is a complex question that requires a complex answer. I'm honestly not too familiar with that type of study but I'm sure I could help you walk through it. Make a topic on the forum and it'll be easier for both of us to interface on how this can be done: feassistant.com/forums/ls-dyna/ 3) I use OBS studio. It's free and works pretty well! Let me know if I did not understand your questions correctly.
@@UnpopularMechanics Thanks a lot for replying. 1) If you go to any examples tutorials in LS-Dyna website they have given reduced keyword with all values etc. I wish to do something similar. So CAXedit can do that I guess. I'll check it out. 2) Wow! What a nice forum. Will surely do it asap. Thanks.
I guess I may not have understood the first question. Feel free to post a picture with an example of what you are talking about to the forum and I’ll probably be able to help.
@@UnpopularMechanics But from the same page, by clicking on the adjacent tab, the same page, you can download the zip files that would contain the entire .k file
Thanks for the inituative video man ! Unfortunatelly I have one small problem with the analysis. My block is going through the ground like there is no ground ( . I've checked the contact settings and material settings but they all look correct. ı would be happy if you help me to solve this issiue.
I don't know if it's of any interest, but I know what you need to change. You have to change the order on the contact between plate and block. So not SSID 2 and MSID 3, but instead SSID 3 and MSID 2.
Great Tutorial. I'm new to LS Dyna at it helps a lot. I'm exactly following your instructions in the video but still getting the issue that the block penetrates the ground. Do you know why this could be?
I would check that there are no initial intersections between the bottom of the cube and the plate before you run the simulation. Then try to change the contact to a segment set to segment set Automatic Surface to Surface contact
Hey, great video and a huge thanks! You make learning this program much easier! But I have a question for you or someone else who can help me: I followed your Tutorial step by step. However when I run the simulation (over 12 minutes btw, University Linux PC :D ) the Bottom to plate contact doesn't seem to work. The block always glitches through the plate. I double checked if the entities and the surface to surface keyword is correct. I translated the block another 0.5mm in positive z direction, to see if it's already through the plate before the ball even hits the block. But it still won't work. Anyone got some ideas what could be wrong here? Thanks!
EDIT: I just swapped the Slave and the Master, so that the plate is the slave and the block is the master... and it worked?! Any idea why that could be? :D
Ah I see good call with that. Usually only matters when there is a big difference in element size between the parts. Usually the part with larger element size should be the master. Not sure which way that would be in this case because I haven’t looked at this model in quite a while haha
Thanks for answering man! Element size is the same, the block only has way more of them... no idea why it worked for you but not for me :D Anyways thanks for the content and the support! :)
Ball goes through block and plate Problem FIX: Check your material properties for the block and the ball, make sure that they are different. MID 2 for the ball is Elastic 8e-6|40|0.45 ..................... MID 1 for the Block is Elastic: 1e-6| 0.001| 0.3........ I did this and it worked because the problem is from having the materials for the ball and block to be the same I think the reason for that mistake is that I didnt accept the changes properly. HOPE this helps
Topic is misleading... I was expecting something related to 'sensor' in LS-Dyna. "Sensor" has different meaning in LS-Dyna. Other than that, good vdo. Thnx.
Download the model shown in the tutorial here:
feassistant.com/product/ball-and-block-ls-dyna-example-models/
Consider joining our FEA-focused community forum if you are interested in learning more!
feassistant.com
I generally don't comment on tutorials, but I just cannot begin to express how useful these are and how easy it is to follow. Thank you for these awesome tutorials!
@@kartiktripathi9441 that’s very kind of you to say. I’m glad they helped!
@UnpopularMechanics I have a quick question. Let's say that I want to simulate a structure made out of just steel tubes welded together in 3D space. Can I just create that structure by creating linear elements and assign beam type to it? Also, how would the results vary between beam and truss elements?
Thank you so much! I absolutely like your authentic, down to earth style. You just casually say "cookies are done". It´s sooo random, but also provides some comic relief in this very technical video.
Haha thanks for the kind words. Glad it was helpful
Thx you so much mate.
~From all the interns learning finit element simulation in few days.
Great content! You're seriously improving quality of life for years to come.
Haha glad to hear it!
Is no one literally going to talk about global turn-ons at 10:40? :D Great video never the less!!
Great content! Thank you so much! Please upload other videos also!
Hi there, Thanks so much for the presentation really clear and very useful.
When I set mine up I found the ball passes through the block contact? do U have any suggestions about why that maybe? I rechecked everything and even inverted master and slave but it still happens? Sure I have messed up cant see where. Also is it possible to post the .k file so we can compare? kind regards
A
Hmm this is a good idea, I'll see if I can find a place to upload all my tutorial models so that people can check them directly.
@AlexC the same thing happened. Were you able to sort the issue out?
17:45 What is that solver called that you are using for the simulation?
30:32
Could it be because the ground cannot move and consequently has to take all the force from the block..whereas the block can dissipate the force to be absorbed as internal energy..hence the lesser force spike in 'Ball to Block' as compared to 'Block to Ground'?
Also i think surface area concept expects the opposite to happen..right?
Great work, thank you. Regarding the energy unit, kN-mm. One J (Joule) of energy, equals to the force of one Newton acting through one meter (Nm). To be consistent with other units, kJ (Kilo-joule) is kN-mm.
When I run this on LS-Run, it immediately shows the status 'Terminated' with red. What can be wrong?
Thankyou for sharing! Great content!
Sir, I want to apply a certain downward force from the top of the structure, then want to simulate blast effect on that loaded structure, I am succeeded by doing without load, but unable to apply force on that structure. Could you provide a hint that how to apply force/load on a certain part of the structure, I will be thankful to you.
You can do this a few ways. The easiest would be to apply a point load at the top of the structure using *Load_Node_Point where you have to select the node to apply the force and provide a force vs time load curve (LCID). You can also define a local coordinate system to apply the load in a specific direction, but you don't need to if your global coordinate system works for the direction that you want to apply the load.
@@UnpopularMechanics But sir, by applying load through "Load_Node_Point" can I solve explicit problem such as "Blast" effect on structure?
Thanks, it help me so much, do you have curs on line?.
Some one would you like to help me in ls dyna? I'm nee in the software
good job!! it's useful for me .Thank you so much.
Thanks, glad I can help
Unpopular Mechanics I am doing reinforced concrete in ls prepost, how to make a model of reinforced concrete and the relationship of the bond and slip of reinforced concrete. I hope you have a video like this, appreciate it if you can
@@AmeenTopa okay. Thank you so much!
Hello, I don't know if you'll read this comment but I have come across some problems with the simulation. In LS-Run I couldn't choose to export the file in d3plot, as you showed in the video. Do you know what is wrong ?
I love your tips and content. there is a question. during selecting the contact you said it's better to choose segment set!! there are differences? or because you just want to choose top and bottom you do that?
Honestly, there are a lot of small details regarding contacts that you can modify, depending on issues that you are seeing in your model. Segment sets within a contact are more accurate for a 3D mesh than a basic part to part contact.
Awesome video. I wonder where r u from and may u make abaqus tutorials videos in future
Once upon a time, I said I would learn Abaqus.
And then I didn't. So sorry about that.
Thank you for the tutorial - I'm just getting into this, and it is rather daunting. I'm following your tutorial, but when I compute, it throws negative volume errors. It occurs for a single solid element. If I stiffen up the block to 0.1, I can complete the simulation, but I would enjoy seeing the jello-effect that you observe. Can you advise on how to debug this? Cheers.
I am doing an analysis of load blast on the structure and inserted the stress-strain curve graph in "DEFINE_CURVE" option for the structural response to high impact blast, but in output, I am getting relevant data such as displacement, velocity, the stress in standard units (meters, second, pascal, newton) but getting acceleration in 6th power, which is damn high, where I am failing?
Hmmm that’s strange that you are getting realistic velocity and displacement values but not acceleration. Have you tried differentiating your velocity to get acceleration to check that it’s not just a bug with prepost?
@@UnpopularMechanics Yes sir I have differentiated the velocity but result is similar.
You're just amazing! Amazing content and I hope you upload more videos on LS Dyna. I've few questions.
1) How do I get the reduced keyword text file so that I can print it for reference etc.
2) How do I do a convergence study of a complex model. i.e if I need to make a mesh finer after a simulation without deleting anything.
3) Which Software you used to record these tutorials?
Thanks
Thanks I really appreciate the kind words!
1) Do you mean how do you collapse the keyword .k files so that only the *Keywords are showing? I use a text editor called CAXedit that makes it easy but there are probably some plugins for editors like textpad and notepad++ that can do something similar.
2) This is a complex question that requires a complex answer. I'm honestly not too familiar with that type of study but I'm sure I could help you walk through it. Make a topic on the forum and it'll be easier for both of us to interface on how this can be done: feassistant.com/forums/ls-dyna/
3) I use OBS studio. It's free and works pretty well!
Let me know if I did not understand your questions correctly.
@@UnpopularMechanics Thanks a lot for replying.
1) If you go to any examples tutorials in LS-Dyna website they have given reduced keyword with all values etc. I wish to do something similar. So CAXedit can do that I guess. I'll check it out.
2) Wow! What a nice forum. Will surely do it asap. Thanks.
I guess I may not have understood the first question. Feel free to post a picture with an example of what you are talking about to the forum and I’ll probably be able to help.
@@UnpopularMechanics But from the same page, by clicking on the adjacent tab, the same page, you can download the zip files that would contain the entire .k file
Thanks for the inituative video man ! Unfortunatelly I have one small problem with the analysis. My block is going through the ground like there is no ground ( . I've checked the contact settings and material settings but they all look correct. ı would be happy if you help me to solve this issiue.
I don't know if it's of any interest, but I know what you need to change. You have to change the order on the contact between plate and block. So not SSID 2 and MSID 3, but instead SSID 3 and MSID 2.
@@el_barto2012 Hey, yes that worked. But do you know why is it so. Shouldn't it not matter which way we assign the segments?
Hi, can you help me, because I don't understand how to read data base me
Great Tutorial. I'm new to LS Dyna at it helps a lot. I'm exactly following your instructions in the video but still getting the issue that the block penetrates the ground. Do you know why this could be?
I would check that there are no initial intersections between the bottom of the cube and the plate before you run the simulation. Then try to change the contact to a segment set to segment set Automatic Surface to Surface contact
Hey, great video and a huge thanks! You make learning this program much easier! But I have a question for you or someone else who can help me:
I followed your Tutorial step by step. However when I run the simulation (over 12 minutes btw, University Linux PC :D ) the Bottom to plate contact doesn't seem to work. The block always glitches through the plate. I double checked if the entities and the surface to surface keyword is correct. I translated the block another 0.5mm in positive z direction, to see if it's already through the plate before the ball even hits the block. But it still won't work. Anyone got some ideas what could be wrong here?
Thanks!
EDIT: I just swapped the Slave and the Master, so that the plate is the slave and the block is the master... and it worked?! Any idea why that could be? :D
Ah I see good call with that. Usually only matters when there is a big difference in element size between the parts. Usually the part with larger element size should be the master. Not sure which way that would be in this case because I haven’t looked at this model in quite a while haha
Thanks for answering man!
Element size is the same, the block only has way more of them... no idea why it worked for you but not for me :D
Anyways thanks for the content and the support! :)
When is the third video comming?
I’m sorry I haven’t had time to finish it. I will try to get it uploaded this week
thank you. very helpful
I'm glad it was helpful! I'll have part 3 out soon.
Thanks for all your tutorials!
I am new to LS Dyna and am working on NURBS patches. Can you please provide some tutorials on NURBS elements too?
thanks.very useful
Glad that you found it useful!
amazing!!!
Thanks alot
No problem Nik
Ball goes through block and plate Problem FIX: Check your material properties for the block and the ball, make sure that they are different. MID 2 for the ball is Elastic 8e-6|40|0.45 ..................... MID 1 for the Block is Elastic: 1e-6| 0.001| 0.3........ I did this and it worked because the problem is from having the materials for the ball and block to be the same I think the reason for that mistake is that I didnt accept the changes properly. HOPE this helps
Topic is misleading... I was expecting something related to 'sensor' in LS-Dyna. "Sensor" has different meaning in LS-Dyna. Other than that, good vdo. Thnx.