Hi Sir
Material assignment problem resolved. But Sir again the results from the abaqus seems not feasible. The bone is bending to large which seems to be practically unfeasible. Sir this project is very important for my thesis work completion. Plz check my files that what is going wrong:confused:. Im attaching the all files. codings are given below-
the converter scales the forces, which it shouldnât, when you apply these â1000 ⌠1000â. So you need to change the amplitudes with the names ending with (1,2,3) or you could change the CLOAD definition from:
Hi Sir
If i want to do the analysis of this model in walking condition instead of standing model. So please suggest me the workflow to do this and which tutorials will helpful for me?
Regards,
Mohit.
Sir
You mean to say that all that we have been done is for the walking posture. Sir we want to compare stresses on implant in walking condition and a standing posture. So i want to know that how can i compute forces on standing model. because i was thinking we have done the standing model part and now i was to do analysis in walking condition.
Thanks.
Sim 1: Export forces for standing model in an XML format, construct FE model like discussed before
Sim2: Export forces for walking model in an XML format, construct FE model like discussed before
The principle does not change, but the first one will have a static load, whereas, the second one will have a dynamic load (check *amplitudes). And another problem - your walking simulation needs to be perfectly consistent with the standing model. Otherwise you will have 2 different bone lengths, e.g. MoCap model utilizes a subject-specific C3D file, meaning that the bone length changes.
Possible option for you is to compare different frames of the gait simulation to generate 2 different FE models.
Hi Sir
It means that a output file which contains varying amplitudes are walking simulation and with constant amplitude are standing model.Sir my output have a varying amplitudes. Sir you discussed earlier about the generation of .xml file for both cases(static or varying amplitudes). I was checking the tutorials regarding fea interface to generate .xml file for that cases. I am unable to find the point regarding static or varying amplitudes generation of the .xml point. Sir could you have any research papers regarding this?
Thanks.
I am not sure what seems to be the problem. The XML file is automatically generated with the corresponding loads - for no motion it will have constant amplitudes and for models with some motion they will vary. You donât need to do anything special in this sense.
For your education - a) try taking a standing model, export forces for a relevant segment, b) make a single bone move by adding some velocities in the mannequin file, export forces for a relevant segment. Leave all settings exactly the same (number of steps, etc). Process both files equally through the converter and make a line by line comparison. What you are expected to see is that some amplitudes will change from being constant (case a) to be dynamic (case b).
The workflow for setting up your FE models is not supposed to change.
Thanks Sir
Now iam getting your point exactly.It means i should work in the mannequin files to assign motion. And all another procedure should be same.:o
Dear Sir
I have been completed the last problem with your suggestion. Now i take a example of tumor femur bone. In this case i have not done any unit conversion so in this i not use 1000 string in this. I am using original units in this case and all other workflow is same.Scaling and forces are also seems to be ok. But in this case also the results from abaqus seems infeasible. Amplitudes and forces in this case seems to be ok. In last problem i use the trick suggested by you which which works. But now i am confused use that trick or not because i never do any unit conversion or nor 1000 string in this. Please check the issue that what step we are doing wrong that every time we are getting same problem.
Thanks.
Sir
We tried with both set of material properties(mpa and gpa). In this case we apply following material properies-
Youngs modulus 21e9 , poison ratio .3 and density 1600.
I checked the forces - the maximum is in the joint reaction forces (300-400N), and some moments as large as 1Nm. That level of load cannot bend a properly defined bone with realistic materials properties like you suggest in the picture.
So i would still blame the consistency of units, the implementation of materials properties and constraints. Please check it thoroughly and possibly try to exaggerate stiffness values to see whether that changes something or not.
And this does not seem to be related to the AnyBody and conversion anymore - itâs already a purely FEA task. So please refer to the relevant forums if you struggle. The code that you sent seems to be correct.
Hi Sir
To check my workflow i first done the analysis of clavicle bone,in this everything goes well. Then second think which i had done- i export the clavicle bone .inp file (from anybody tutorials) in 3-matic and try to measure it dimensions, in this software was enable to measure it. Could you tell me in which software this file has prepared. Idea behind that to check the exact workflow ,that where is the devil is occurring in the approach.
Thanks.
the clavicle exported from AnyBody would be written by our STL generator (no magic there). You canât probably measure this one because it is in meters - it will look very small in 3matic (at least it did for me in MIS). So the recipe would be to scale it to mm.
But not sure whether this helps you to move further or not.
What I could recommend you is to take your femur bone and apply a compressive force, say, 3-400N from the femoral head distally and the same load proximally in the knee joint. This is somewhat similar to what you see in your AnyBody analysis. I think it will bend your model in a similar fashion, which would indicate that you have a problem with the materials properties. There might also be some moment involved - please check the values in the output files.
But judging from the files you sent - it is not really the loading problem that your femur bends a lot, the loads are reasonably small. So there could be unit/material property problems.
Hi Sir
We discussed this issue with abacus team.Because the team member that represents abaqus in our country, they do not know more about anybody. I show him the clavicle example in anybody tutorials. And do all operations as discussed in tutorials.They said they can only help us in edit of constraints and loads. I was remained surprised that at a side where mostly loads occuring in clavicle is bending . And our sterss-strain distribution is also not matching with tutorials. In this case i dont play with any abaqus activities where may be the chance of error.
I just add density additional 1000.I not change the constraints as discussed in tutorials)to the outermost point.
So sir question is that if i define all in anybody(MATERIAL,CONSTRAINTS,LOADS) in the case of clavicle, just run the analysis so why my results is nit matching with anybody tutorials. And edit of constraints is an mandatory step or optional?
2) There may be another possibilty that results may be ok but my mind thinking may be not matching with results. Because i seen in some research papers that hip stem and bone are bending from top in anybody webcasts. Could you share with me the exact results file of clavicle or any other bone that you done in abaqus+anybody(.odb) just the sake of matching of yours results. This will help me to compare results and may i find what is going wrong.
Thanks.
We do not keep the simulation database files since we have all the input that can generate the data. As well as that the simulation results may change slightly depending on the improvements we apply to the repository from time to time. But you should be able to get exactly the same result if you follow all the tutorial steps.
So if you think the results are wrong - there are only a few reasons:
AnyBody results are not valid (you can try validate these results with some experimental data from various sources).
Conversion failed - you can clearly read the conversion result and see what went wrong, compare with the output XML. The input deck is a text based file, which is quite readable. You should understand what is going on - if not PLEASE refer to the Abaqus keyword manual
Base FE model is wrong (mat properties most likely): What you can do is to forget about AnyBody converter and try applying loads from literature or common sense (say apply expected reaction forces from the known body weight).
Everything is correct including results and loads, but your output display uses some sort of scaling factor (FE packages often do that to highlight smaller displacements).
So please try figuring out which one is wrong. If the first two - i will look into that, but you would need to explain what is exactly wrong. If the 3 and 4 are the problems - this is not really the right forum to figure out.
Hi Sir
In the case tumor bone i think that anybody results are wrong. Because in this i apply the loads(300-400 N) loads manually in abaqus as you suggested in previous replies and apply constraints manually with same material properties. So results are very ok in this case(no too much bending as in case of anybody loads). Sir you have been checked the all files that all the loads are ok (that can not bend bone too much) .From this point it is clear that there is no issue of material properties because there is not so bending as i did this same task manually. So sir i already checked all conversion issues. We did the scaling first and then prepare mesh and we did not use 1000 string in this.I want to request that please run the analysis in your system and check what is going wrong:(.
Thanks.
This simulation has been performed many times and no strange behaviour was observed (unless users made an error). I dont see how your analysis is different to make AnyBody results wrong - I presume you are using some sort of standard model to obtain loads, standing for example. I have looked through the files you sent and see that you have compressive loads of less than 400-500 N, and bending moments of 0.7Nm. All these loads seem to be very reasonable and should not bend properly constructed femur model too much.
I cannot run the test at this point - temporarily we are out of the Abaqus license. But I can run the test using ANSYS - but it wonât be exactly the same simulations.
In any case from what I have seen up until now there is no problem on the AnyBody side. I would need a better demonstration of the problem. Try sending the mesh and material properties definition as a text file to see what exactly is going on. You could also send the model that you use to extract the loads.
Dear Sir
As your suggestion, im trying to do analysis in ansys itself. In this im confused where the fe mesh file is to placed in template-
AnyOperationShellExec ConvertToAPDL={
Show=On;
FileName = âAnyFE2APDL.exeâ;
Arguments = â-i âŚ\Convertor\cload.xml -o âŚ\Convertor -t .\Convertor\APDLTemplate.txtâ;
WorkDir=âC:\Users\ADMIN\AppData\Roaming\AnyBody Technology\AnyBody.6.0.x\AMMR.v1.6.2-MyDemo\Application\Examples\StandingModel\Output\Convertorâ;
};