Learning Forum

[JoshikaS]

Hi!

I am using ANSYS 2020R1. I am trying to model a hemp fiber composite with epoxy as the matrix. How do I represent this on Ansys Composites PrepPost?

Do I have to specify the hemp and epoxy materials separately in Engineering Data and then combine them into one fabric in ACP? Or is there another method I'm not aware of?

I can't use Material Designer as I only have the Student version.

Any help would be great, thanks!

[Sean Harvey]

So, Material Designer is the easiest option. Without that, I would recommend you using the rule of mixtures to compute the equivalent material properties. If you search for rule of mixtures, you can find resources. This can help you determine Ex, Ey, Gxy, vxy For orthotopic materials, there are 9 constants. Some of these are more difficult to derive when with limited data, but you can make assumptions such as if the hemp is unidirectional, then transversely isotropic situation is present and can be assumed. This can lead to the relationship that Ey=Ez, Gxz =Gxy, nuxz=nuyz. Then Gyz = Ey/(2*(1+nuyz)) You may have to estimate nuyz. If you access to the composite books by Tsai or Tsai and Hahn or others, there are typically discussions on material symmetry and it also covers these topics for serving material properties.
Another more accurate method would be to model the fiber/matrix using an RVE and the parameters can be determine, much like the way Material Designer computes the material properties.
Regarding your question of defining separately, and combine into a fabric, the fabric in ACP is meant to take the already homogenized orthropic material (hemp+epoxy) and just include the thickness.
I hope this helps. Thank you.

Regards Sean