Progressive node placement (mesh)

[Jfrisch]

Dear FEAP-Users,

I want to mesh a cracktip and need to use a progression in node placement. E.g. I need to place 35 nodes along a horizontal edge between coordinates x=0 and x=1 with a progression in distance of the nodes. The nodes near to the end-node at x=1 can be quite far from each other but the distance between the nodes near the crack tip at x=0 has to be of order 1E-8 or 1E-9 (so node 1 is placed at x=0 and node 2 is placed at x=1E-9 would be favorable and afterwards a linear progression to node 34 at e.g. x=0.8 and node 35 at x=1). Is there any possibility to get a mesh like this using the BLOC-command or something similar or have I to compute all the coordinates manually and set the nodes manually to the position I want them to be?

Kind regards,
Jan Frischmann

[Prof. R.L. Taylor]

It would seem you can get something similar to what you describe by using a 9-node block with the node near the crack tip placed close to the 1/4 point between the edges.  You will have to experiment with the placement to get precisely what you need.

 

[Jfrisch]

So there is no way to pass a ratio of element lengths to the bloc-command?

[Prof. R.L. Taylor]

You can compute the ratio using the attached

[Jfrisch]

The Question is in which way do I need to create my input-file to tell FEAP using a e.g. quadratic placement of nodes during automatic mesh-creation using the bloc-command? Your document is a way to calculate the distances of a given mesh if I read it correctly but not how to tell FEAP to create such a mesh.

[Prof. S. Govindjee]

If you know what you want, then you can use Prof. Taylors write up to compute where to place the mid-side nodes on the master-block.  This will then give you the grading you want.  FEAP does not allow you to directly input the grading.

[Jfrisch]

Ah ok, I do know what I want to do - the mesh is describeable in only few words but an automatic progression in nodal placement would've made the implementation of this idea much easier. Thank you both for your help!