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Hello sir....Thank you very much for learning tutorials... However I could not understand why we need to devided applied load by number of nodes...In practica, whole suface, hence all nodes will be subjected to 4 KN load....But we definded 4/820 KN on each node.....this need to be done in all kind of simillar probelm ?
If we didn't divide by the no. of nodes, then we will be applied 4kN on each nodes of the surface. If the surface has 100 nodes, then the total load applied with be 400 kN!! If you don't want to divide, no problem. But the force of 4kN will be concentrated on one single point which is not the case in real life.
Thank you so much. I have learned a lot from your tutorial. I want to define preloaded under gravitational force before impact simulation which is called dynamic relaxation. Can you make tutorial or guidance how to do it?
Very thankful to you sir. Sir, I'm solving an explicit model (blast effect on the structure) but initially, I will have to apply load/force on the structure (as per condition), and then have to analyze blast effect on the structure. After inserting load curves for selected nodes, the solver is showing error termination. How to overcome this type of issue?
Hello. Thank you for the tutorial. can you please explain the function of the all "implicit" you used? i understand others but i don't seems to know what use of implicit.
Implicit keywords are to activate and control the implicit time integration scheme. For further information about this, you can look online for a document called "Tips and Tricks for Successful Implicit Simulation" by Dynamore.
Thanks for the video it was very helpful. I tried to perform the same steps on my part but i guess due to bigger part i got an error saying Memory is short. How can I get rid of it.
Dear Ameen, I always learn from your turtorial evertime. As I model a single column and a regid cylinder was placed at top to aviod exessive local damage ( I merged duplicate nodes between the column and cylinder already). I have applied axial load the same as you. I have a few questions related to my modeling. 1) Does it need to defind the contact between regid cylinder and column, and its friction (FS, FD)? 2) I have watched yours turtorial (Reinforced Concrete and Wrecking Ball), when you defined Load_body_Z, you putted scale factor SF=1 but when I checked model truck F800 they put SF=9806. What these stand for? Do I need to assign gravity load on my model? Thanks in advance🙏
Dear Met mey, If you merge the duplicate nodes, then no need for any contact. SF is the scaling factor, in my tutorial, I defined the curve for gravity as 9.81 so there is no need for any scaling. But in the truck model, the curve has a value of 1, that's why they put 9806 as the scaling factor. They are using tonne, kg, mm, s units that's why the gravity constant is 9806 not 9.806 in their model.
Hello Dear!! How to decide the time duration of confinement and deviatoric loading if one wish to do triaxial test on cylindrical concrete specimen. Besides this, can u also give me some advice as in plotting curve, axis magnitude are not visible. Thanks in advance...
The start time of boundary conditions can be controlled wirh SPC SET BIRTH. And end time can be controlled by DEATH in SPC SET. Regarding the graph, you can check my tutorial on post processing.
This value depends on the RAM, not the CPU specs. You can try the same value, if it didn't work, then reduce it. But this simulation is not that big, you can leave it as default, it would be just fine.
dear sir，May I ask why I used your method to analyze the bearing capacity of reinforced concrete columns? Why did the result obtained be greater than the force I applied? Thank you for your answer
Thank you for the video. I am trying for similar parameters but getting an error 60022 (IMP+22) saying "LS-DYNA Implicit is not supported in single precision, Please switch to DOUBLE Precision (I8R8) version". Can you suggest the solution to this?
The problem is quite clear. You are using single precision solver for implicit analysis. Implicit analysis can run only on double precision, for example smp_d_R10.
Thank you for the tutorial. It is very useful! I tried modeling the exact same and if I increase the load it looks as if not all the nodes at the end where the force is applied have the same displacement. It looks as if every other node has a large displacement. The other nodes only have small displacements. Do you know why this occurs and how to fix it?
First thing to check, your nodeset. Make sure all the nodes on the surface is defined in the set. If this still doesn't work, then you can make a rigid plate on the top, then apply the force or displacement on that plate.
Thank you for the tips Mr Topa. I have already checked the nodes, and it looks as though they all are defined. So I think I'll try your solution with the rigid plate.
Thank you for your video. I want to run compressive test of concrete cube. i do not know how to put experimental data for materials. which materials we have to choose. would you mind to help me?
Hello sir, i was trying to do the post processing display settings as shown in the video but I wasn't able to find the tool. Is it due to me having a student version?
No. It might be that you are using a different version of LS-PREPOST. For more tutorials about postprocessing, you can check my video "Postprocessing with LS Prepost".
Hi, I found this video to be very informative and I quite like it however, I followed the video to a tee and keep getting an Error 20001 reading 1st control card with improper format in line 2. Is there there a quick generic fix that any knows of for this? Thanks
Hello. First of all great job on the tutorials, but when I want to define LOAD_NODE_SET and want to accept it i get warning Data of repeat card widget changed, but not saved. Then I save it but still getting same warning. What could be a problem to cause this issue?
ahaha, in 1 hour I noticed that in my version of LS-Dyna there is a subwindow with buttons insert, delete and replace (but it was not in the video), and AmeenTopa talked about these buttons in the comment.
am dealing with a concrete filled steel tube subjected to blast load.. i need to find out the mid-height deflection of the tube. for the above said problem i have divided the full length of the tube into three parts so as to find the deflection in the middle part. but i have been unable to establish the contact between the respective parts... can u suggest me the appropriate keyword that is to be used for establishing the contact between the parts.. waiting for ur reply... thanking u
i have also tried with one part that is without dividing but was unable to find the mid-height deflection of the tube.can u suggest me the CONTACT keyword that is to be used for creating the contact between concrete and steel..
You can follow the same steps used here. However, instead of making solid cylinder. You make a hollow one. Check my tutorial on the following link where I covered how to make shell cylinder. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-KVUBsmqkRxk.html
@@AmeenTopa means that the force distribution is taken from the total force to be evenly distributed on the surface, right, sir? Or is the total force distributed in the nodes sir?
if it inputs the load at each node, is there a way if I directly input the load on the surface with the load evenly distributed? or is there a way to calculate how many nodes are input on the load curve as a divider of the load? 
@@nathasya2492 if you do not want to calculate the force per node, then you can use LOAD RIGID BODY. With this option, you can directly put the total force to be applied.
So can we load already meshed surface with nice flow to get more accurate results.... and can we do this stimulation in different ways with less number of steps?
If I intend to utilize an overpressure time history as a blast load, would the procedure be the same? If so, how does the software differentiate between the defined curve for pressure versus time and the curve for load versus time, given that the units for force and pressure are distinct?
Hi, just a basic question. In LS-Dyna, in the legend for stress, why is compressive stress positive and not negative? For my specific problem, I have both positive and negative values of stress. How do I know which is compressive stress and which is tensile?
Following the standard convention in mechanics of solid, positive is tensile stress and negative is compression. What do you mean by 'compressive stress'? There is only x, y, z stress, shear stress, and effective stress options in contour plots.
@@AmeenTopa I mean, when looking at the legend for effective stress, for example, the legend goes from negative values to positive values. There are both negative and positive values of effective stress in the model. What do positive and negative stress values mean?
Could you please tell the unit you are using for time. According to the other units you are using, it should be ms. But in the termination time you chose 1. Does it mean that the simulation is only for one millisecond?
Hey Ameen, could these steps be used in simulating the compression of reinforced concrete concrete columns except for having different material properties and models? Thanks
@@AmeenTopa hello Ameen, i have created a concrete column model to run a buckling test but i get an error message saying negative eigenvalues, could you please advise on how i can solve this issue. Thank you
No problem. Sometimes, you need to apply distributed load instead of point load. The method used in Tutorial 4 is for you if you want to apply distributed load.
I am just wondering about the NCPU=8. Was the computer that you used for the static analysis is an HPC? I was trying to model a large-scale model and it required time of 55hrs. any suggestions to speed up the simulation?
CPU time depends on many factors such as: file size, number of elements, and elements quality. If your keyword file size is 200 Mb or above, then it is normal that it would take that amount of time.
@@AmeenTopa Thank you very much for the reply. The file size is 23 Mb though. If I want to do a simulation for the half of the model (cut along a symmetric axis), how should I apply the boundary condition to the cutting plane? Also, do I need to input or consider any other keywords or factors in addition to the boundary condition? and after I simulate the half model, how should I scale up the values for the full model?
If that's the file size, and you are doing static analysis, then I assume you are using implicit solver. If my assumption is right, then you can use variable time step, and control the initial time step. For model reduction, you don't need go remove or reduce the load, you can simply apply boundary conditions at the symmetric plane with BOUNDARY SPC SET or use SPC SYMMETRY PLAN condition like in my video here. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-Xidr0p6EplQ.html
@@AmeenTopa Thank you very much. You are right, I am applying a static load through a spherical ball on a wall. Ye, I tried with implicit solver with variable time step (after watching one of your videos) but it is still taking longer time. I will try with the SPC SYMMETRY PLAN and check. Thank you very much for your much helpful videos and advice.
@@amzzano For implicit analysis, everything should be fixed and there is not 'loose' ends. If there is some gap between the ball and the wall, then this might cause your run time to go very large. The ball should be touching the wall at the beginning of the simulation. The wall (if you are using shell or solid part) should be fixed too at its boundaries.
am dealing with reinforced concrete column under blast loading. not getting how to make contact between the concrete ,stirrups and main reinforcement. Please suggest keyword for contact between the three. thank you
hi sir, i am new to this software and trying to learn from your tutorial. however, when i try to run analysis, it says error 70004. my steps and files saved as in the video.
Check my tutorial on Torsion. Quasi static analysis is usually done with implicit. Using explicit will take decades. In my Torsion tutorial I used mass scaling which reduces the computation time.
Hello Sir, i want to attach Cfrp wrapping material to concrete column, it is just like frabic. I am not able to do this?. Any solutions, as i am not able to get results.
Vinod, you can model with Beam Elements, or shell elements as in this video. Instead of making solid cylinder, you can make hollow cylinder. The rest of the things should not different.
In define_curve...when I changed value of SIDR to 1 then while plotting it is showing invalid curve id ......this is happen when I am doing dynamic relaxation method.....any solution?
Ameen Topa thank you for this....but do you have any pdf for dynamic relaxation method because its hard to understand this method....if you have any video or document ..that will be helpful for me
"Finally after 32 minutes the analysis is done"That is because of the 99 completely unnecessary intermediate steps...using an implicit solver like an explicit one :)Still a great tutorial though!
Thanks for all your tutorial videos Ameen. It so easy to follow. I'm currently trying go learn how to do a compressive testing of a concrete specimen and tried to follow this video. Could you please do a video on how to simulate the compressive testing on a concrete cylinder sample? It differs from this problem in a sense that force is applied until the concrete sample cracks, and the output required for the test is a stress-strain curve. (I could only find a tutorial on this using ABAQUS ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-PTRQib7C6po.html) It would be greatly appreciated!
