How can I plot results generated by a conditional equation using a Python Result object?

Nikos Kallitsis

In my Mechanical Model, I need to plot values at each node based on the following conditional equation:

delta = (SX + SY + SZ) / SEQV

if delta >= 0:
rV = EPTO_EQV / (a0 + b0 ** (c*delta))

if delta < 0:
rV = b0

This cannot be achieved using the standard User Defined Result object in Mechanical, as it does not support conditional statements. Importing post-processed data and plotting them with a User Defined Result would only provide values for a single time point.

Is there a way to accomplish this using DPF with a Python Result object?

Nikos Kallitsis

You can use the following script:

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

# Uncomment this function to enable retrieving results from the table/chart
# def table_retrieve_result(value):# Do not edit this line
    # import mech_dpf
    # import Ans.DataProcessing as dpf
    # wf = dpf.Workflow(this.WorkflowId)
    # wf.Connect('contour_selector', value)
    # this.Evaluate()

def define_dpf_workflow(analysis):
    import mech_dpf
    import Ans.DataProcessing as dpf
    import math

    mech_dpf.setExtAPI(ExtAPI)

    # Get components from field container
    def get_field_container(field_container, index):

        op = dpf.operators.logic.component_selector_fc()
        op.inputs.fields_container.Connect(field_container)
        op.inputs.component_number.Connect(index)
        my_fields_container = op.outputs.fields_container.GetData()

        return my_fields_container

    #Get path to result file
    analysis = ExtAPI.DataModel.Project.Model.Analyses[0]
    filepath = analysis.ResultFileName

    #Data sources
    dataSources = dpf.DataSources()
    dataSources.SetResultFilePath(filepath)

    # Model
    model=dpf.Model(dataSources)

    # Equivalent Plastic Strain result
    epto_op = dpf.operators.result.plastic_strain_eqv()
    epto_op.inputs.data_sources.Connect(dataSources)
    epto_op.inputs.requested_location.Connect('ElementalNodal')

    epto_fc = epto_op.outputs.fields_container.GetData()

    # Equivalent Stress result
    seqv_op = dpf.operators.result.stress_eqv_as_mechanical()
    seqv_op.inputs.data_sources.Connect(dataSources)
    seqv_op.inputs.requested_location.Connect('ElementalNodal')

    seqv_fc = seqv_op.outputs.fields_container.GetData()

    # Stress results
    s_op = dpf.operators.result.stress()
    s_op.inputs.data_sources.Connect(dataSources)
    s_op.inputs.requested_location.Connect('ElementalNodal')

    s_fc = s_op.outputs.fields_container.GetData()

    # Field Containers
    epto = get_field_container(epto_fc, 0)[0]
    seqv = get_field_container(seqv_fc, 0)[0]
    sX = get_field_container(s_fc, 0)[0]
    sY = get_field_container(s_fc, 1)[0]
    sZ = get_field_container(s_fc, 2)[0]

    # Constants for equation
    a0 = 1
    b0 = 2
    c = 3

    # Application of conditional equation
    resVal = []
    num_ent = epto.ScopingIds.Count

    for i in range(num_ent):

        epto_Data = epto.GetEntityDataByIndex(i)
        seqv_Data = seqv.GetEntityDataByIndex(i)
        sX_Data = sX.GetEntityDataByIndex(i)
        sY_Data = sY.GetEntityDataByIndex(i)
        sZ_Data = sZ.GetEntityDataByIndex(i)

        resVal_Data = []

        for j in range(len(epto_Data)):

            delta = (sX_Data[j] + sY_Data[j] + sZ_Data[j]) / seqv_Data[j]

            if delta >= 0:

                rV = epto_Data[j] / (a0 + b0 ** (c*delta))

            else:

                rV = b0

            resVal_Data.append(rV)

        resVal.append(resVal_Data)

    resVal_field = dpf.FieldsFactory.CreateScalarField(num_ent,'ElementalNodal')
    [resVal_field.Add(id = seqv.ScopingIds[i], data = resVal[i]) for i in range(num_ent)]

    # Plotting
    output = dpf.operators.utility.forward()
    output.inputs.any.Connect(resVal_field)

    dpf_workflow = dpf.Workflow()
    dpf_workflow.Add(output)
    dpf_workflow.SetOutputContour(output)
    dpf_workflow.Record('wf_id', False)
    this.WorkflowId = dpf_workflow.GetRecordedId()

Instead of ElementalNodal you can also request Nodal location.