Get successive elements with max stress in depth of structure

Pernelle Marone-Hitz

I'd like to select an element, and based on that starting point get the successive N elements with max stress in the depth of the solid body.

Pernelle Marone-Hitz

Here is an example of Python Result that :

• allows the user to :
  • select an element "start_elem" on the surface of a solid body
  • define the number of in-depth layers that should be considered
• calculates and plots a result as follow:
  • retrieve the stress on start_elem
  • select the elements connected to start_elem, but only the elements in the depth of the structure, and identify the element with max stress on the selected elements
  • iterate this procedure N number of times, N being the number of layers defined by the user
• plot the identified elements and evaluate the average stress on these elements

This is achieved by editing the Property Provider of the Python Result as follows:

def reload_props():
    
    this.PropertyProvider = None
    # Create the property instance
    provider = Provider()


    input_group = provider.AddGroup("Input")
    ns_prop = input_group.AddProperty("Elemental Named Selection Name", Control.Expression)


    nb_layer_prop = input_group.AddProperty("Number of Layers", Control.Double)


    output_group = provider.AddGroup("Output")
    output_prop = output_group.AddProperty("Average stress over selected elements", Control.Double)
    output_prop.CanParameterize = True
    output_prop.ParameterType = ParameterType.Output
    
    # Connects the provider instance back to the object by setting the PropertyProvider member on this, 'this' being the 
    # current instance of the Python Code object.
    this.PropertyProvider = provider

As a result, the properies of the Python Result should look like this:

And the Script to use in the Python Result is:

def post_started(sender, analysis):# Do not edit this line
    define_dpf_workflow(analysis)

def define_dpf_workflow(analysis):
    
    # import DPF
    import mech_dpf
    import Ans.DataProcessing as dpf
    mech_dpf.setExtAPI(ExtAPI)
    
    # Connect to result file
    dataSource = dpf.DataSources(analysis.ResultFileName)
    
    # Retrieve property values
    selection_name = str(this.GetCustomPropertyByPath("Input/Elemental Named Selection Name").Value)
    n_layers = int(this.GetCustomPropertyByPath("Input/Number of Layers").Value)
    
    # Retrieve mesh 
    model=dpf.Model(dataSource)
    mesh=model.Mesh # whole mesh
    skin_mesh=dpf.operators.mesh.skin(mesh) # skin mesh 
    skin_nodes=skin_mesh.outputs.getnodes_mesh_scoping() # get nodes of skin mesh
    conv_to_elems=dpf.operators.scoping.transpose(mesh_scoping=skin_nodes,meshed_region=mesh) # convert to elements
    skin_elems_scoping=conv_to_elems.outputs.getmesh_scoping_as_scoping() # create a scoping with skin elements
    
    # Retrieve Von Mises stress on elements
    s = dpf.operators.result.stress_von_mises()
    s.inputs.requested_location.Connect('Elemental')
    s.inputs.data_sources.Connect(dataSource)

    # Get starting element from named selection
    selection_name=selection_name.upper()
    # Start element
    elem=dpf.operators.scoping.on_named_selection(named_selection_name=selection_name,
        requested_location='Elemental',data_sources=dataSource)
    elem_scoping=elem.outputs.getmesh_scoping()
    
    # Retrieve max stress on selected element
    s.inputs.mesh_scoping.Connect(elem_scoping)
    s_max=dpf.operators.min_max.min_max(s.outputs.getfields_container()[0])
    
    # Collect element id and stress values
    elem_ids=[elem.outputs.getmesh_scoping().Ids[0]]
    smax=[s_max.outputs.field_max.GetData().Data[0]]
    
    # Find next n elements with highest stresses but don't take into account any element with free surface (i.e. linked to outer skin)
    for i in range(0,n_layers):
        conv_to_nodes=dpf.operators.scoping.transpose(mesh_scoping=elem_scoping,meshed_region=mesh) # get nodes of selected element
        neighbour_mesh_op= dpf.operators.mesh.from_scoping(scoping=conv_to_nodes,mesh=mesh) # get elements attached to nodes
        # Remove skin related elements
        diff_scoping=dpf.operators.scoping.intersect(scopingA=neighbour_mesh_op.outputs.getmesh().ElementScoping,scopingB=skin_elems_scoping) 
        inside_elements_scoping=diff_scoping.outputs.scopingA_min_intersection.GetData()
        # Remove any of the previously identified elements from the scoping
        el_ids=list(inside_elements_scoping.Ids)
        for el in elem_ids:
            try:
                el_ids.remove(el)
            except:
                pass
        inside_elements_scoping.Ids=el_ids
        # Find element with highest stress value
        s.inputs.mesh_scoping.Connect(inside_elements_scoping)
        s_max=dpf.operators.min_max.min_max(s.outputs.getfields_container()[0])
        # Collect element id and stress values
        next_elem_id=s_max.outputs.field_max.GetData().ScopingIds[0]
        elem_ids.append(next_elem_id)
        smax.append(s_max.outputs.field_max.GetData().Data[0])
        # Before ending the loop, update start element to be last one found
        elem_scoping.Ids=[next_elem_id]
        
    # Set output value
    this.GetCustomPropertyByPath("Output/Average stress over selected elements").Value=sum(smax)/len(smax)
    
    # Display mesh will be only selected elements
    selected_scoping=dpf.Scoping()
    selected_scoping.Ids=elem_ids
    selected_scoping.Location='Elemental'
    s.inputs.mesh_scoping.Connect(selected_scoping)
    display_mesh=dpf.operators.mesh.from_scoping(scoping=selected_scoping,mesh=mesh)
    
    dpf_workflow = dpf.Workflow()
    dpf_workflow.Add(s)
    dpf_workflow.SetOutputMesh(display_mesh.outputs.getmesh())
    dpf_workflow.SetOutputContour(s)
    dpf_workflow.Record('wf_id', False)
    this.WorkflowId = dpf_workflow.GetRecordedId()

The starting element should be defined thanks to a named selection (and by providing the name of said NS in the property of the Python Result):

With an standard equivalent stress plot as follows:

This is how the Python Result will look like for 2 layers defined: