Learning Forum

[Yassine Naffeti]

Hi,

I am using PyMAPDL on python to process a modal analysis and optimize it. 
I solved the same model previously on the software ANSYS Mechanical directly and the number of nodes was 616169 in the software. 
Then I exported the simulation file using cdwrite with the option "ALL" containing all geometry, material property, load, and component data. Then I loaded it with python and solved it again but I get a small difference in the number of nodes, but the results like eigenfrequencies are the same. The problem is not only the number of nodes is different from what I could see on ANSYS Mechanical, it is also incoherent within some arrays/variables that I get from APDL. I will explain this more as follows, this is a python code: 

1) print(mapdl.mesh) 

Output:
ANSYS Mesh
  Number of Nodes:              616211
  Number of Elements:           322069
  Number of Element Types:      220
  Number of Node Components:    0
  Number of Element Components: 0

2)  also when getting the number of nodes using mapdl.mesh.n_node it gives back the same number

number_nodes = mapdl.mesh.n_node
print(number_nodes) 

Output: 616211

3) However when I store the nodes in an array the length of it which should correspond to the number of nodes is different from we got previously

nodes = mapdl.mesh.nodes
print(len(nodes))

Output: 616256

4) using mapdl.db.nodes 

print(mapdl.db.nodes)

MAPDL Database Nodes
Number of nodes: 616256
Number of selected nodes: 616256
Maximum node number: 616256

5) and again when I retrieve the displacements for all the nodes I get an array not matching the number of nodes that I get previously from mapdl.mesh.nodes  ; I get the displacements for 616211 nodes only which is different from 616256

all_displacements = mapdl.post_processing.nodal_displacement("ALL")
print(len(all_displacements))
Output: 616211

To put you in context: this is causing me a problem because I have the coordinates of some points where I want to get the displacement. But first what I do is that I determine the closest node to the point and then get the displacement of it from the array all_displacement. But in this case the number of nodes is varying in this interval [1, 616256] and the displacements I get are for only for 616211 nodes. So let's say I want the displacement for the node number 600000, if I use the nodal displacement array that I get from postprocessing I don't know if it actually corresponds to the same node. 

Every help is appreciated. Thank very much in advance. 

[Aniket]

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