Retained Volume Optimisation
- Lennart Krueger
- SHK
Step 1: Start MSC Apex Generative Design
The program starts and you can directly create your optimisation model
Step 2: Model generation
You can either create the geometry directly in MSC Apex Generative Design or import already existing files. You can import .xt, .xb, .step, and .sldprt files into the program.
Import/create the Design Space including the Non-Design Spaces in MSC Apex Generative Design. For this Bracket the Design Space was imported.
The CAD-file includes several solids. The desired Design Space, as well as the dummy part for an electric motor and the needed screws to connect the parts. The latter ones are the Retained Volumes which will be used later on in the model set up.
Open the Design Space Tool in the Optimization Tools to select the imported Geometry as the Design Space.
Create the material Steel, PA12 and Aluminium in the Materials editor. Assign PA12 to the Design Space, Aluminium to the electric motor housing and Steel for the screws.
The specific values needed are the Young's Modulus, Poisson ratio and Density.
The Tension Strength is the maximum allowable stress for the material.
Name | Young’s Modulus | Poisson ratio | Density | Tension strength |
|---|---|---|---|---|
Steel | 192.000 MPa | 0,3 | 7,97 g/cm³ | 515 MPa |
Aluminium | 72.000 MPa | 0,34 | 2,7 g/cm³ | 200 MPa |
PA12 | 1.700 MPa | 0,39 | 0,9 g/cm³ | 42 MPa |
Step 3: Definition of boundary conditions
Go to the Loads & Boundary Condition Tool to enter the loads and fixations. Displacements, Forces, Moments, Gravity and Pressure Loads can be applied using different selection options.
In this case one force and one moment are applied to the electric motor:
Name | Force/Moment/Pressure/Gravity | Direction | Value |
|---|---|---|---|
Force-Moment1 | Moment | My | 15 kNmm |
Force-Moment2 | Force | x | -3 kN |
Four constraints are created and attached on the four inner surfaces of the holes at the outer attachment points:
Name | Direction |
|---|---|
Constraint 1 | x, y, z (=0) |
Constraint 2 | x, y, z (=0) |
Constraint 3 | x, y, z (=0) |
Constraint 4 | x, y, z (=0) |
Step 4: Interface Creation
Interfaces have to be created for every functional surface - so every surface where a boundary condition is applied to. With this Tool an offset to the inside with the input “Non-Design Space Thickness” and an offset to the outside with the input “Machining Allowance is created. The Offset Distance is expanding the Interface to the set value to create material on front faces.
Four Interfaces are created on the interfaces between the Design Space and the electric motor and four on the inner surfaces of the fixation points at the bottom. Hide the motor as well as the screws to have a better view. A Non-Design Space Thickness of 3 mm, an Offset Distance of 4 mm and a Machining Allowance of 1 mm is entered. Now select the surface and confirm the selection (MMB).
Step 5: Definition of the Generative Design Configuration
In the next step the interaction between the Retained Volumes and the Design Space is defined. For this the Generative Design Configuration Tool is used. Start the Tool and choose the corresponding objects for each step, then click the MMB. For this configuration, only the Design Space is selected as Initial Design Space and the electric motor and screws as Retained Volumes
Note: The prior defined Interfaces are automatically chosen after the selection of the Design Space.
After the selection click Create Configuration and Apply Configuration. The GD Configuration 1 and the corresponding Generative Design Part 1 are created. If you right-click on the Configuration object and choose edit, you can validate or change your selection. It should look like this:
Attention:
The Generative Design Part 1 is a copy of the initial Design Space. Thus, the initial Design Space can be hidden.
Boundary Conditions which have been attached to the Design Space and not to a Retained Volume need to be re-applied to the new Generative Design Part 1!
Step 6: Definition of Events (load cases)
The next steps are defined in the Studies area.
All boundary conditions must be assigned to the specific load cases, which are defined as Events. The number of Events can be changed by adding/deleting Events to the GD Scenario. The assignment of the boundary conditions to the Events can be made in the Loads & Constrains Window. The already created loads and constraints that concern the Design Space are listed in this window and can be activated for each Event individually.
Active in Event1: Force-Moment 1 and all Constraints
Active in Event2: Force-Moment 2 and all Constraints
Step 7: Definition of optimisation parameters
The optimisation parameters are selected in the Studies Area as well.
Manufacturing Method: Generic AM
Failure Criteria: Von Mises
Stress Goal: 12 MPa
Select the Strut Density: Medium
Select the Shape Quality: Balanced
Set the Complexity Setting: 8
Don’t forget to save the project!
Step 8: Starting the optimisation and visualizing the results
If all data is correct, the optimisation can be started and tracked in the Post Processing. The Analysis Readiness function checks if all information is provided and the optimisation can be started.
All result iterations are displayed as soon as they are available. Furthermore, you are able to stop the optimisation in this selection area. However, a Restart is not directly possible.
The optimisation is finished after 64 iterations (Shape Quality: Balanced).
You can check the status of the optimisation in the GD Status and get more information on Warning and Error messages. This can be done directly in the Post Processing as well as in the Studies tab for an optimisation that has already run.
Generative Design
You can always change the Strut Density, Safety Factor and Complexity to influence the results and try out different options
The Complexity can be increased for a higher resolution and more detailed result (increased calculation time!)
The Strut Density influences the structures which are formed during optimisation
Step 9: Visualization of Stresses, Displacements & Mass
The legend can be influenced in different ways. You can add and reduce the stress/displacement steps, enlarge different steps and set new minimum and maximum values. The mass of each iteration can be visualized with a diagram.
You can go back to the model setup by clicking the Exit button in the right bottom corner.
The whole MSC Apex Generative Design project with all results can be downloaded here:
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