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Error: Material direction is almost normal to the elements

Amol_22063

I am getting error Error: Material direction is almost normal to the elements. I am trying to understand why I am getting this error I have modelled composite material with surface sandwich shell property. Changing direction vector in property instead of 0 to 0.0001 get rid of this error.

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HyperCrash

v2022.0

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Michael Herve

Hello Amol,

the reference vector is a vector which will be projected to your shell element for defining the orientation of the element in case of orthotropic or anisotropic material.

If your reference vector is (almost) colinear to your element normal, then the projection cannot determine any direction.

Please note that Hypermesh offers more flexible tools than HyperCrash for defining material orientation.

Hope this helps,

Best Regards,

Michael

Amol_22063

Is there any way to update or visualise it in hypermesh. I have tried running my model by update shown in image but run is showing errors.

Michael Herve

hello Amokl,

you can start getting familiar with composite capabilities in HyperMesh with the 2 videos below:

https://youtu.be/a6-78ab7Ttk?si=Cp1BQ5ySuClWgn7o

https://youtu.be/-cIj3NQXpPs?si=EjsSYYrVtjKAT3fg

Best Regards,

Michael

PaulAltair

What is the orientation of your mesh? Your settings suggest you have a plane that has a normal close to Z axis (e.g. in XY) in which case an orientation of 1,0,0 would make more sense here, changing slightly away from Z may give a 'valid' model but it is unlikely to be correct. The important thing is to choose a base orientation that gives the expected reference vector for your laminate. Both/Either HC and HW can visualise the orientation so you can check it.

Amol_22063

Hi Paul,

Composite component in my model is shown below. I have checked element normal and material orientation direction is not matching. Material orientation is I have checked it using option 2D>Composite>Properties. I have also tried using orientation of 1,0,0 in my property card. Still getting error after running model.

PaulAltair

Ok, it is likely because you have the 'flanges' around the edges of the part that are quasi perpendicular to the main plane of the part, a single vector defined for the whole part is difficult to establish since a vector that gives a good projection in one area may be unsuitable for another, visually, looking at your screenshot, X=1, Z=1 would probably be valid, but as I commented before the projections would likely then still not be 'correct', it might be better to switch to ply based composite definition (/PROP/TYPE51 and /PROP/TYPE19 for example) and assign the element orientation at the element level using phi-s angles and set def_orth = 1 on the ply to be sure you get the intended reference orientation.

Amol_22063

What if I define web as one component and flanges as other. Also provide different property to each component.