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You can either create the geometry directly in MSC Apex Generative Design or import already existing files. You can import for example .xb, .xt, .step, and .sldprt files into the program.
Import/create the Design Space including the Interfaces (Non-Design Spaces) in MSC Apex Generative Design as one solid. For this Bookshelf the already prepared Design Space was imported.
Open the Design Space Tool in the Optimization Tools to select the imported Geometry as the Design Space. You can delete the empty part “Bookshelf” because it is no longer needed.
Create the material in the Materials editor and assign it to the Design Space. In this case the material behaviour is Isotropic.
The specific values needed are the Young's Modulus (192372 MPa), Poisson ratio (0.3) and Density (7.97e-6 kg/mm3).
The Tension Strength is the maximum allowable stress for the material and is set to 320 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.
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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.
All surfaces on which a boundary condition is applied can be selected directly as an interface with the “Select Faces from Loads and Boundary Conditions” button. The Boundary Condition surfaces will be highlighted and can be selected/deselected. With “Apply” the Non-Design Space Thickness, Machining Allowance and if available Offset Distance values will be applied to the selected surfaces.
Three Interfaces are created to insert screws and fixate the Bookshelf to the wall. Therefore, an Non-Design Space Thickness of 2 mm and a Machining Allowance of 1 mm is entered. Because not only the inner faces touching the screw but also the front and back face are supposed to contain material and have sharp, functional faces, an Offset Distance of 3 mm is entered. Now select the inner surfaces of the fixation and confirm the selection (MMB).
All Constraints are selected in the table and the settings are applied.
One Interfaceis created on the top plate to use this as the book storage. Therefore, an Non-Design Space Thickness of 1mm and a Machining Allowance of 1mm is entered. Now select the top plate and confirm the selection (MMB).
Note: Sometimes the Interface Offset (usually displayed in red) is not visualized due to a limitation. The correct value will be considered in the optimisation.
Step 5: 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 Eventscan be changed by adding/deleting Eventsto the GD Scenario. The assignment of the boundary conditions to the Eventscan 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 Eventindividually.
If you have followed all the steps, you will see two studies at this point. The first study refers to the imported geometry and can be deleted. The second study refers to the Design Part and is used to set up the optimisation parameters.
Active in Event1: Force-Moment 1, Constraint 1, Constraint 2 and Constraint 3
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The optimisation parameters are selected in the Studies Area as well.
Manufacturing Method: Generic AM
Failure Criteria: Von Mises
Stress Goal: 2 MPa
You can switch between the Safety Factor and Stress Goal in the properties panel by clicking the gear wheel.Select the Strut Density: Medium
Select the Shape Quality: Balanced
Set the Complexity Setting: 14
The Stress Goal seems to be chosen quite low for the material selection however when considering the low loading conditions, it is a suitable choice. The resulting stresses deliver a well-formed design.
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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 start.
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.
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Step 8: Visualization of Stresses, Displacements & Mass
Inside the Post Processing the von Mises stress and the displacements are visible for all iterations and for every Event
The Scale can be influenced individually
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.
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You can always change the Strut Density, Stress Goal and Complexityto influence the results and try out different options
The Complexitycan be increased for a higher resolution and more detailed result (increased calculation time!)
The Strut Densityinfluences the structures which are formed during optimisation
The optimisations below show the influence of the Strut Density when nothing else is changed.
Strut Density: Medium
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Strut Density: Dense
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Strut Density: Sparse
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The whole MSC Apex Generative Design project with all results can be downloaded here:
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