How to solve energy error problem of dropping simulation
Altair EmployeeHi all,
In my dropping simulation, the energy suddenly rose and the time step was controlled by foam self contact and drop dramatically. From the animation of the process, the mesh of the foam deform dramatically at time t=4.16s, and at the same time the kinetic energy sudden rose.
The engine out file was attached and the contact parameters were listed in file ContactParameter.txt. The contact between the metal plate and the foam was defined and the self contact of foam was also in consideration.
In addition, the part 6 was metal and Ishell=24 QEPH formulation was used. part 86 was foam and Isolid=24 HEPH formulation was used.
So how should I do to solve this problem?
Best Wishes
Roy
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Answers
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Hi Roy,
The possible causes for this can be:
•Badly defined material.
•Contact interface (stiffness, gap) not correctly defined.
Check the foam material parameters and ensure the inputs are correct. Any badly defined parameters can result in weird behavior of the material.
Check the self contact interface created.
If the issue persist, please share the model file in the secure dropbox.
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Altair Forum User said:
Hi Roy,
The possible causes for this can be:
•Badly defined material.
•Contact interface (stiffness, gap) not correctly defined.
Check the foam material parameters and ensure the inputs are correct. Any badly defined parameters can result in weird behavior of the material.
Check the self contact interface created.
If the issue persist, please share the model file in the secure dropbox.
Hi George P,
The material law for the foam was LAW70, and the parameter was listed in the attachment file. I don't know if there was some problem.
I have read the card of /MAT/LAW70, however I don't think I have understood.
1. How to set the initial Young’s modulus and Maximum Young's modulus? What's the effect of these parameters? How to get this parameters?
2. What's the relation ship between initial Young’s modulus and Maximum Young's modulus and Stress-Strain curve? I think the tangent of Stress-Strain curve was Young's modulus.
3. The mesh of the foam showed before and the self contact parameters (/INTER/TYPE7/29) was listed in the attachment. How to modify parameters to solve the problem?
Best Wishes
Roy
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Hi Roy,
I'll update you regarding the material parameters. I recommend you to go through the Material Laws in the Theory Manual of RADIOSS where the formulation details are explained.
As a workaround, you can try modelling the foam with law 33 material which is also used to model foam.
Please go through the Crash e-book on Contacts (Page 145 onwards) where recommended contact parameters are specified.
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Altair Forum User said:
Hi Roy,
I'll update you regarding the material parameters. I recommend you to go through the Material Laws in the Theory Manual of RADIOSS where the formulation details are explained.
As a workaround, you can try modelling the foam with law 33 material which is also used to model foam.
Please go through the Crash e-book on Contacts (Page 145 onwards) where recommended contact parameters are specified.
Hi George P,
I set the contact parameter by referencing the documents you mentioned. However, the problem was occurred as before. I don't know how to correct. Do you have any suggestion?
Best Wishes
Roy
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Hi Roy,
Did you try modelling with /MAT/LAW33?. Can you share the model file to my dropbox link?.
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Altair Forum User said:
Hi Roy,
Did you try modelling with /MAT/LAW33?. Can you share the model file to my dropbox link?.
Hi George P,
I have share my model file to your dropbox link. Please find it and help me with the problem. Thank you.
Best Wishes
Roy
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Hi Roy,
Please check the rigid bodies in the model. Many slave nodes are again selected as slave nodes for other rigid bodies. Álso, please check the Type 2 interfaces defined in the model. And there are many penetrations in the model. Please clear these and try running.
I'll also update very soon.
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