As you can see attached below, I am trying to simulate stress distribution of Dental implant and Jaw bone under dynamic loading using ABAQUS/STANDARD with Dynamic/Explicit step. I also used Mass scaling with target time increment of 1e-06 for studying quasi-static effect with ignored inertial effect. But After it successfully Runing for some time it give error with excessive distorted element as well as with another error message of "The ratio of deformation speed to wave speed exceeds 1.0000 in at least one element". So is there any one who can suggest me solution to my problem?
Thank you so much!
Hello Dawit Alemayehu,
first of all it is very difficult to give any advice without seeing the *.cae- or *.odb-files.
Nevertheles, from my own experience, using mass scalling with target time increment is not always suitable approach (By the way, it seems that you use 1e-07 target increment time in presented results). Such approach can lead to VERY high mass scalling at the parts with small mesh size, which could lead to such errors ("excessive distorion of elements"). Try to add to your field output "EMSF" variable, which represents "Element mass scaling factor". If for some elements it is more than 100, this could be the reason for such errors.
So in the end I would recommend you to change your mass scalling approach to scalling by factor. Normally maximal mass scalling factor that gives more o less reliable results is not higher than 100. If you use higher values then you should be very carefull with interpretation of obtained results.
Sincerely,
Pavlo
Dear Pavlo Pavliuchenko;
Thank you so much for the valuable answer, if you have time to check my cae file I will be more than happy to forward just text me your email. And based on your feedback I enabled the EMSF and yea it run without error but the stress in the spongy bone(Cancellous bone) is higher than expected it should be like 5-10MPa but now it is more than 200MPa and in the other componetes also the stress is beyond expected which is unacceptable.
if you do have any additional feedback please let me know, thanks a lot.
Hello Dawit Alemayehu ,
introduction additional field output, such as "EMSF" should have any influence on the simulation. It looks like you have additionaly changed something in your model. I avised you to add this output to check the real mass scaling factor in your model. Check, if for some parts your mask scalling factor is to hight (>100). It could be the reason of you problems.
Did you also changed the mass scalling approach from target increment time to mass scalling factor?
Sincerely,
Pavlo
Dear Pavlo Pavliuchenko,
Yes> but I didn't do any change other than adding EMSF in the field output request. But I know from your recent feedback I tried to change the mass scaling from target time increment to mass scaling and i put 100 in the mass scaling it really runs slow it may not finish after two days even.
still need additional help! thanks!
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