Learning Forum

[zz200]

Hello everyone,

Sorry for the question, I am very new to ansys.

I have two models, A is the original 3D model and B is the deformed 3D model. These models are exactly same before the deformation, which means they have same nodes. The deformation is performed with Hypermesh. After deformation, I would like to calculate the displacement of all surface nodes and use the surface displacement information to help me analyze the internal nodes displacements. My question is how to input the surface displacement to ansys and calculate the internal nodes displacements?

Thanks!

[Rameez_ul_Haq]

,if you want to just select the surface and apply the necessary displacement, then you can use the displacement option directly under the static structural tree. Just right click and you will see it. You can enter the value of the displacement that you want the whole face (on average) to have this displacement, on X, Y and Z axis.
If you want to apply the displacements independently on each node of the face, then just make a named selection of that node (I mean do this separate named selection for all the nodes that you want to apply the displacement on), again enter the displacement from static structural tree, and then instead of 'Geometry Selection', go for 'Named Selection'. Choose that named selection onto which you want to apply displacement to that node. Then again enter the values of the displacements in X, Y and Z axis.

[zz200]

Thank you so much. I am wondering how to get the displacements for these nodes. These models have 2000 nodes. My thinking is to import these two models, before and after the deformation, to ansys and use ansys to find the displacements for each surface node. Then, apply these displacements to the original model surface to find the internal node change and displacements.

[peteroznewman]

You have a text file with 2000 rows of data in the format:
node_ID, Xu, Yu, Zu
for the coordinates of the undeformed surface nodes.
You also have a text file with the same 2000 rows of data in the same format:
node_ID, Xd, Yd, Zd
for the deformed coordinates of the surface nodes.
Put those two files side-by-side in 8 columns of a spreadsheet and in the next three columns calculate the deformation as:
Dx = Xd - Xu
Dy = Yd - Yu
Dz = Zd - Zu

[zz200]

Thanks! I tried to used Named Selection to select all nodes. However, for Nodal Displacement, could any one help me about importing the displacement file? For example each node have different displacements, so should I write a file like below as input?
node A -1,-1,-3
node B 1,2,3
......
Could any one help me about how to import a file like this? Thank you!

[peteroznewman]

One way to apply displacement to the 2000 nodes is to have 6000 rows of commands.
The command to apply a displacement to a node is D, Node_ID, Label, Value
For example, if node 1001 has a deformation Dx = 0.01, Dy = -0.005, Dz = 0.001 the following 3 rows apply that Displacement.
D, 1001, UX, 0.01
D, 1001, UY, -0.005
D, 1001, UZ, 0.001
´╗┐Note that you have to keep the Units in Mechanical set correctly when you use commands like this because these commands are applied using the current unit setting unless you take steps to control that.

[zz200]

Thanks a lot. I am sorry but I am still facing two problems. The first problem is data import problem. I exported external models from hypermesh and wants to use them as input of ansys workbench. I tried to convert the file in different format, such as *.inp, *.nas, but none of them works well in ansys. The figure below shows the problem. I expected the geometry part should be a green mark since this is an external model. But it shows a question mark. Also, the geometry should be a solid model since I used tetrahedral mesh in the proprecessing software.
Another problem is the displacement analysis. In this project, I would like to obtain the model(internal node displacement) when I apply the surface node displacement. Thus, I defined the surface displacement. However, in ansys, it does not allow me to solve unless I define a fixed support for the model. But ideally, every node can move and I don't know what constraints should I add here. Below is an example of this analysis, I moved the surface node to align the model. In this case, I don't need any fixed support as constraints.



Thanks a lot.

Happy new year!

[peteroznewman]

Export both formats from Hypermesh (*.inp and *.nas) for the undeformed and the deformed mesh. Please put those four files into an archive file with a *.7z or *.rar file extension, then attach that archive file to your reply. In your reply, say what version of ANSYS you are using.
This project might be simpler to do using the Mechanical APDL interface instead of the Workbench interface.

[zz200]

Thanks. I am using 2021 R2 student version.

[peteroznewman]

I was able to open the .nas files and overlay them in Femap.
I found this is a surface mesh of triangles. I can fill it with solid elements, but it is a lot coarser mesh than is shown here:
What is the original source of the data? Can you get the finer mesh?

[zz200]

Sorry. The original source is from the 3d slicer software for medical imaging. Here is the finer mesh version. Thanks a lot!