Rule of Mixtures Composite query

[MaBra]

Hi All,
Making a 3D sandwich panel in Patran with plies simulated by 3D hex8 elements, I've thought a question about the reverse stack fabric. I mean, if the upper external solid has built through 4 plies [mat1/mat2/mat3/mat4], how can I reverse the stack [mat4/mat3/mat2/mat1] to make the last solid?

I've tried to create a new coordinate set which upside-down the normal coord, in this way the sequence should be the opposite. Is this right?

Thank you in advance for your reply.
Regards.

 

[ESPcomposites]

Why are you using hex elements to represent the plies? Are you saying that there is a hex for each ply or that you are trying to represent the laminate as a single hex?

What does this have to do with the rule of mixtures?


Brian

http://www.espcomposites.com

 

[MaBra]

Hi Brian, it's just a test to understand patran limt. I've had some trouble to optimize the fiber orientation using the laminate option, so i've want to try RoM. However there is no one hex every plies but just three solid layers. Obviously the mid layer shows the core. What do you think about?

Thank's,
Maurizio.

 

[ESPcomposites]

You seem to be using the terms wrong. The rule of mixtures is applicable at the micromechanics level (combining fiber and matrix to determine a ply property). To convert the ply/layup into an effective laminate (or equivalent material), you would use lamination theory.

I don't know what your goal is, but carpet plots would be a quick way to start if you want to use the solid to represent the facesheet stiffness. You could also use an orthotropic shell for the facesheet instead of the hex. There are many options.

Brian

http://www.espcomposites.com

 

[MaBra]

I've already done a laminate simulation by lamination theory but, results doesn't satisfy me. Therefore I've thought to do a complete solid simulation. To use a shell element 2D surfaces are required for external layers, but CLT doesn't works in right way, because it crush every ply together and the algorithm doesn't see different orientation.
Anyway, thank you a lot. If you have some suggestion, feel free to write me.

Regards,
Maurizio.