How to extract unaveraged stresses at a node using DPF?

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Rohith Patchigolla
Rohith Patchigolla Member, Moderator, Employee Posts: 139
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edited June 2023 in Structures

How to extract unaveraged stresses at a node (at all elements the node shares) using DPF?

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  • Rohith Patchigolla
    Rohith Patchigolla Member, Moderator, Employee Posts: 139
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    Below script shows how one could extract unaveraged component stresses (in this case stress Y) at a node. The values corresponding to all the elements connected to the input node id are printed at the end.

    Note: This approach cannot be used for getting unaveraged principal/equivalent stresses, as the midside node stresses will be incorrectly computed.

    ##Unaveraged Nodal Stresses based on Node Id. 
import mech_dpf
import Ans.DataProcessing as dpf 
mech_dpf.setExtAPI(ExtAPI)

#Get the data source (i.e. result file)
dataSource = mech_dpf.GetDataSources(0)

#Enter the node ID
nodeId = 100

#get Connected Elements
mesh = dpf.operators.mesh.mesh_provider()
mesh.inputs.data_sources.Connect(dataSource)
node_connectivity = mesh.outputs.getmesh().NodalConnectivityPropertyField.GetEntityDataById(nodeId)

#Create operator
sy_op = dpf.operators.result.stress_Y() 
sy_op.inputs.data_sources.Connect(dataSource)
sy_op.inputs.requested_location.Connect('ElementalNodal')

sy_fields = sy_op.outputs.fields_container.GetData()
sy_field = sy_fields[0]

#Extend stress result also to mid side nodes
mid_op = dpf.operators.averaging.extend_to_mid_nodes()
mid_op.inputs.field.Connect(sy_field)
sy_field_corner_mid = mid_op.outputs.field.GetData()

print 'Number of elements connected to node',nodeId,'=',len(node_connectivity)

for id in node_connectivity:
    elem_num = mesh.outputs.getmesh().ElementIds[id]
    elem = mesh.outputs.getmesh().ElementById(elem_num)
    node_index = elem.NodeIds.IndexOf(nodeId)
    stress_y = sy_field_corner_mid.GetEntityDataById(elem_num)[node_index]
    print 'stress at element',mesh.outputs.getmesh().ElementIds[id],'and node',nodeId,'is',stress_y

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