Warning in solid element definition
Altair Employee Hi guys, I'm a very beginner user of radioss. I tried to model an honeycomb impact attenuator in Hypercrash following the 'Crash Box-Tutorial'. When I run the model in Radioss I obtaine the following warning:
'** WARNING IN SOLID ELEMENT DEFINITION
DESCRIPTION :CHANGED CONNECTIVITY OF 3D ELEMENT ID=4101 TO AVOID NEGATIVE VOLUME'
Then the simulation stops after only 1 cycle.
I followed also the advice in this discussion (http://forum.altairhyperworks.com/index.php?/topic/18360-negative-volume/), but nothing to do.
Some of you could explain me which is the problem? I uploaded the model.
Thank you very much.
Andrea.
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Altair Employee Hy George! Thank you for your fast reply. How have you solved my problem?
Thank you also for your good advices!
Andrea.
Altair EmployeeHi Andrea,
As mentioned in the last reply this error was cleared by deleting those failed elements.
As a good practice, after the model set up is done in HyperCrash, go to Quality>Model Checker and run the same. This will list all the possible modelling errors in the model and you can clear the same before running the analysis.
Altair EmployeeAaaa ok! Very useful advice. Thank you!
Radioss is running the file that you have attached from about 1 hour. Is it normal or it's taking too long?
Altair EmployeeHi Andrea,
This can due to very low time step in the model. Please review the engine out (_0001.out) file so that you can review the time step and what is causing the tie step to drop.
It can be due to an element, a node or an interface.
•For an element, check the related material (especially its Young modulus and density in case of an elastic-plastic material; and its viscosity in case of a visco-elastic material). There must not be an error in the units system that this data is given in.
Check the size of the element, since elemental length is proportional to time step.
•For a node, check the characteristics of connected elements. If the node is on the master side or the slave side of an interface, this interface must be verified.
•For an interface, the gap of the interface must be verified if some failure happens on the master or the slave side of the interface.
Once this is cleared you can run the simulation without time step being dropped.
Else you can try with imposing time step in the model. You can watch this webinar http://www.altairuniversity.com/learning-library/considerations-about-time-step/ which describes the same
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Altair EmployeeOk. I'll try to review these parameters. Thank you George.
Hi Andrea,
There were some failed solid elements in the model which were deleted.
Please try with the attached files.
Meanwhile, we have an updated honeycomb impact attenuator analysis tutorial which can be accessed at http://www.altairuniversity.com/learning-library/modeling-and-analysis-of-honeycomb-impact-attenuator/
Since you are a beginner in RADIOSS I recommend you to download our Crash Analysis With RADIOSS – A Study Guide ebook which will be a good reference for you.
Also you can learn the basics from out learning and certification from http://certification.altairuniversity.com/
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