How to apply a series of forces from a spreadsheet on faces arranged in a circular pattern?

Tasos

I have a series of force magnitude values in a spreadsheet, and I am interested in applying those forces on the base faces of a circular geometry pattern like in the picture below:

Tasos

Let’s assume that the force values are listed in a meaningful way e.g. in the same order as the sequence of the target faces.

This solution relies on a strategically placed cylindrical coordinate system and utilizes worksheet-based filtering to generate named selections and assign each force value to the corresponding surface. The procedure will be automated with Python scripting inside Mechanical.

An archive of the example project file is also attached for the interested reader to experiment with. A simple spreadsheet with input data is included in the user_files directory of the project.

The first step to implement this workflow is to define a coordinate system. In this example, we set the X axis towards the face where the first load in the list will be applied. Each subsequent force in our data column corresponds to the next face moving counterclockwise. Hence the coordinate system is set accordingly (positive angular coordinates (Y) towards the direction where the next force value is applied). In this example, the coordinate system is renamed to ‘CylCS’ and to reference it in the Python script. We have also set the angle units to degrees for convenience.

In the beginning of the script, we need to define some parameters. In particular:

• The number of faces in the circular pattern n_sectors
• A tolerance value for our selection. In this example we used 1o, since the surfaces are wide enough and we don’t need higher precision.
• A level value, which will be used for filtering. In this example, this is the offset of the target faces from the XY plane.

n_sectors = 8

angle = 360/n_sectors

tolerance = 1

level = 40

Next, let’s import the force magnitude data from the external spreadsheet. For this example, we created a simple column of data in csv format. Like below:

100
200
300
400
500
600
700
800

The data file is placed in the user_files folder in the project directory, which path we can quickly retrieve with Python in Mechanical using the ExtAPI.DataModel.Project.ProjectDirectory command line.

import csv

my_data_dir = ExtAPI.DataModel.Project.ProjectDirectory+'user_files\my_data.csv'

magnitude = []

with open(my_data_dir, "r") as f:

    reader = csv.reader(f)

    for row in reader:

        magnitude.append(float(row[0]))

Finally, for each face we need to iterate over the following steps:

• Create a Named Selection and set a worksheet-based scoping method. This way we can add conditional selection criteria and automate the selection process.
• Add an angular range criterion with respect to the cylindrical coordinate system to select the face of interest.
• Filter the current selection based on the plane where the face of interest resides to remove unwanted surfaces.
• Create a force load on the current selection and assign the corresponding magnitude to the corresponding component (only one component in this example, as we are applying a vertical force).
• Repeat for each sector.

my_sels = []

for step in range(0,n_sectors):

    my_sels.append(Model.NamedSelections.AddNamedSelection())

    my_sel = my_sels[step]

    my_sel.ScopingMethod = GeometryDefineByType.Worksheet

    my_sel.GenerationCriteria.Add(None)

    my_sel.GenerationCriteria[0].EntityType = SelectionType.GeoFace

    my_sel.GenerationCriteria[0].Criterion = SelectionCriterionType.LocationY

    my_sel.GenerationCriteria[0].CoordinateSystem = DataModel.GetObjectsByName('CylCS')[0]

    my_sel.GenerationCriteria[0].Operator = SelectionOperatorType.RangeInclude

    my_sel.GenerationCriteria.Add(None)

    my_sel.GenerationCriteria[1].Action = SelectionActionType.Filter

    my_sel.GenerationCriteria[1].Criterion = SelectionCriterionType.LocationZ

    my_sel.GenerationCriteria[1].Operator = SelectionOperatorType.Equal

    my_sel.GenerationCriteria[1].Value = Quantity(str(level)+' [mm]')

    sec_angle = step*angle

    my_sel.GenerationCriteria[0].LowerBound = Quantity(str(sec_angle-tolerance)+' [deg]')

    my_sel.GenerationCriteria[0].UpperBound = Quantity(str(sec_angle+tolerance)+' [deg]')

    my_sel.Generate()

    my_force = DataModel.AnalysisList[0].AddForce()

    my_force.Location = my_sel

    my_force.DefineBy = LoadDefineBy.Components

    my_force.ZComponent.Output.SetDiscreteValue(0,Quantity(str(magnitude[step])+' [N]'))

0000949851_Example_2025R1.wbpz