What does this mean! Hourglass Possible On Shells?

Sebastian Yang
Sebastian Yang Altair Community Member
edited August 16 in Community Q&A

hi,

 

Recently I have created a Radioss crash model, I exported the 0.rad model and import it into HyperCrash to do a model check, what I find really really confusing is that it throws a warning saying that there are shells with possible hourglass? But what does it even mean? I have not been able to find information about that. 

image

 

I mean, some elements might have a little bit lower quality but some others are just normal shells!! Why would it say that there are problems with those elements? 

 

On the other hand, does this affect my model in terms of hourglass energy in the final results?

 

Any help is appreciated, thank you in advance!

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Answers

  • Johan Dahlberg_20306
    Johan Dahlberg_20306
    Altair Employee
    edited August 13

    Hi Sebastian
    Maybe you can try to use fully integrated shells, and then it might not print this "possible" warning!
    Kind regards
    //Johan

  • PaulAltair
    PaulAltair
    Altair Employee
    edited August 16

    Hypercrash warns for this if your shells are slightly irregular (which in real meshes, they often are), you may experience hourglass issues using classic (Ishell = 1-4) formulations, per John's comment, I would use Ishell = 24 (QEPH) as your default for all shell meshes, it is very efficient and for the vast majority of models means you won't have hourglass issues. Even if the warning persists, you can safely ignore it if using Ishell = 24

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