Today’s script tip comes from Vishnu Venkataraman, Application Engineer at Ansys.
The COG of a body might vary with time as the body deforms and you might be interested in knowing how to compute the time varying COG.
This example also highlights on how you can create your own mesh with DPF.
Methodology followed:
- Get the time varying deformation vectors for all nodes using: dpf.operators.displacement
- Create a mesh region based on existing mesh using dpf.MeshedRegion
- Update the node locations of the created mesh based on the deformation vectors at each time point.
- Find the COG using dpf.operators.geo.center_of_gravity by feeding in the mesh regions at every time point .
Function to find the time varying COG of your model:
Use the below function like:
body_named_selection = ‘MYBODY’
timepoint = 3
find_COG_at_time (body_named_selection, timepoint)Please remember to create a body named selection called ‘MYBODY’
def find coG at time (bodynamedselection, timepoint):
"""
find coG at time ('MYBODY', 3) #Please remember to create a body named selection on the one you are interested in knowing the COG
"""
import mech_dpf
import Ans.DataProcessing as dpf
# Result Data
analysis1 = ExtAPI.DataModel.Project.Model.Analyses[0]
dataSource = dpf.DataSources(analysis1.Solution.ResultFilePath)
# Get mesh
my_model = dpf.Model (analysis1.Solution.ResultFilePath)
my_mesh = my_model.Mesh
# mytime
my time scoping = timepoint
# Get Deformation
u = dpf.operators.result.displacement (time scoping=my time scoping, data sources=dataSource)
disp field = u.outputs.fields container.GetData() [0]
# Create my own mesh from existing mesh
created mesh = dpf.MeshedRegion (my_mesh.Nodes.Count, 0)
for node in my mesh.Nodes:
created mesh.AddNode (node. Id,
[node.X + disp field.GetEntityDataById(node. Id)[0],
node.Y + disp field. GetEntityDataById(node. Id) [1],
node.z + disp field. GetEntityDataById (node.id) [2]])
createdmesh_nodeids = created mesh.Node Ids
for elem in my_mesh.Elements:
created mesh.AddSolidElement (elem. Id,
map(lambda x: creatednesh nodeids.IndexOf(x), elem. CornerNodeIds))
#scoping operator to scope to named selection
ns op = dpf.operators.scoping.on named selection(
requested location='Elemental', named selection_name=bodynamedselection,
data sources=dataSource)
mymeshscoping = ns_op.outputs.mesh_scoping
# cog field
cogfield = dpf.operators.geo.center of gravity (mesh=created mesh,mesh scoping mymeshscoping).outputs.field
# CoG data
return list (cogfield. GetData().Data)
