Modifying 3D tet mesh based on 2D tet shell mesh question

Check your 2D mesh for a closed volume. Then go to '3D' -> 'Tetra mesh' -> See screenshots.

<?xml version="1.0" encoding="UTF-8"?>

<?xml version="1.0" encoding="UTF-8"?>

pka 1991,

Please see a tip and trick document called A checklist for reviewing a tria mesh before tetra meshing it and tips for tetra meshing. here - http://www.altairhyperworks.com/tip_hm.aspx

since your geometry is really complicated, looks like a bone from STL, I suggest you use Shrinkwrap, see 

 HyperWorks Desktop Applications > HyperMesh > User's Guide > Meshing > Surface Meshing > Shrink Wrap Meshing in help,

When you need to convert an .stl representation of a model into a tria/quad mesh; shrink wrap provides a quick and efficient way of achieving this.

Thank you Tinh and Rahul so much. That really helps me.

Dear Rahul

You are righ. But whenever I use shrinkwrap option I have no control on the elements density on the surfaces. I think by going with bias 2D mesh I can create very good 2D emsh on  the surface and then convert them to 3D mode (the thing that Tinh;s suggested)

any way. thank you guys for helping me.

Regards