You trade-off reliability of the result using these tricks like mass scaling. Some tip on sanity check: Check that the kinetic energy (EKE) does not exceed 5-10% of Internal energy (EI) when using mass scaling. Then make sure the work done in propelling mass added in mass scaling (ALLMW) is much lesser than Kinetic energy (ALLKE). Usually, EKE, EVD, EFD should also be much lesser than EI. Finally, if you have to simulate the same model many times, you can check the result with and without using any scaling etc.
Great video, also fantastic thumbnail. I tried it for my explicit problem and the reduced calculation time is significant. However, my load displacement curve oscillates extreme, does it mean I cannot use the density scaling?
Thanks Dr. Ronald for much encouragement. With high density scaling, inertia force starts to dominate. Same is true for artificially increasing the loading rate. Trying Mass calling only in the set of bad/ small elements can reduce the effect. But if you have to use lot of small elements, try a conservative density scaling instead. I believe using small damping in solution step can also help. Share with us if you find a 'sweet' combination.
Nice content and explanation. While adding mass scaling to an explicit problem what are the possible changes in the result?? Whether it will be proportional to actual result or not??
Hi, You trade-off reliability of the result using these tricks like mass scaling. Example of some problem can be: The deformation of bodies can be totally unrealistic if high mass scaling is used. You can see high inertia effect i.e. large deformation where force is applied but small deformation in other part of the model. Stress and reaction forces can be too large. Your requested plots like stress, force etc. can give shaky curves. Simulation might abort. etc.
Hello Sir, I am using shell element S4R type for a composite material, and in the verify mesh section, I cannot select or highlight the elements that might be potentially poor so that I can create a set and assign mass scaling to only those elements. The error message I get is: 'stable time increment could not be calculated for any element in the selected regions. No section assigned...'
How do I calculate Cd if I have a composite material? There are different values to be defined for anisotropic material in the Elastic section in the material property
Sir, I am working on the explicit dynamic problem( milling operation) in Abaqus. I defined the interaction as General contact (Tangential -> penalty, Normal -> Hard contact) Master surface (Rigid) - shell element (tool) and slave surface - Node set of workpiece, but I was stuck with this error. "ErrElemExcessDistortion - STEP 1". Can you tell me what could be the mistake?
You trade-off reliability of the result using these tricks like mass scaling. Some tip on sanity check: Check that the kinetic energy (EKE) does not exceed 5-10% of Internal energy (EI) when using mass scaling. Then make sure the work done in propelling mass added in mass scaling (ALLMW) is much lesser than Kinetic energy (ALLKE). Usually, EKE, EVD, EFD should also be much lesser than EI.
Finally, if you have to simulate the same model many times, you can check the result with and without using any scaling etc.
Very informing. Thank you for sharing this content
Great video , Thank you
Super useful video! Thank you!
Very helpful and good explained video! Thank you!
You made my day！
Great video, also fantastic thumbnail. I tried it for my explicit problem and the reduced calculation time is significant. However, my load displacement curve oscillates extreme, does it mean I cannot use the density scaling?
Thanks Dr. Ronald for much encouragement. With high density scaling, inertia force starts to dominate. Same is true for artificially increasing the loading rate. Trying Mass calling only in the set of bad/ small elements can reduce the effect. But if you have to use lot of small elements, try a conservative density scaling instead. I believe using small damping in solution step can also help. Share with us if you find a 'sweet' combination.
Nice content and explanation.
While adding mass scaling to an explicit problem what are the possible changes in the result??
Whether it will be proportional to actual result or not??
Hi, You trade-off reliability of the result using these tricks like mass scaling.
Example of some problem can be:
The deformation of bodies can be totally unrealistic if high mass scaling is used. You can see high inertia effect i.e. large deformation where force is applied but small deformation in other part of the model. Stress and reaction forces can be too large. Your requested plots like stress, force etc. can give shaky curves. Simulation might abort. etc.
Hello Sir, I am using shell element S4R type for a composite material, and in the verify mesh section, I cannot select or highlight the elements that might be potentially poor so that I can create a set and assign mass scaling to only those elements. The error message I get is: 'stable time increment could not be calculated for any element in the selected regions. No section assigned...'
How do I calculate Cd if I have a composite material? There are different values to be defined for anisotropic material in the Elastic section in the material property
can you do a tutorial for a simple coating experience fretting wear
Sir.. how we can define flux limit ratio by defining stable time increment.?
Sir, I am working on the explicit dynamic problem( milling operation) in Abaqus. I defined the interaction as General contact (Tangential -> penalty, Normal -> Hard contact) Master surface (Rigid) - shell element (tool) and slave surface - Node set of workpiece, but I was stuck with this error. "ErrElemExcessDistortion - STEP 1". Can you tell me what could be the mistake?
Could you also provide us more detail to adjust the mesh for unnecessary portion of the model gradually bigger? Thanks
Hi, here is a video in our channel that might help : ua-cam.com/video/QTBrTqGKopU/v-deo.html
@play time 4:04 / is delta t 7.7e-7???
is it 9.747e-7?
Thank you for pointing it. It was my mistake.
it is a great video, but I have questions, how to calculate Le for complex geometric model?
Hi, each element might have a different Le. Mostly, you don't have a constant Le for the whole model.
3:52 calculation mistake and units. density must be tonn/mm3, E should be in N/mm2 and Le in mm.
I used SI unit system for this example.
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