Dear Marcelo,

the reasons for this problem could be two.

When meshing a hollow semi-cylinder structure meshing problems may arise due to the difference between internal and external radius of the semi-cylinder. Using global seeds would impose the same element dimension in the internal and external radius, which would result in a different number of element between internal and external edges, hence a non-regular mesh.

Another potential source for this meshing issue could be the internal cylinder. When seeding such a geometry elements are distributed starting from the point you used to define the radius of the cylinder in the 2D sketch. This point defines a node, independently on other seeding parameters adopted.

I hope that this helps

Best regards

Hi dear Abedin

You can define small partitions on the section of the carbon fiber with the exact width of the cylinder elements and then try to mesh the fiber . The problem happens when fiber curves around the cylinder and you can use this method .