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Topology Optimization and Reusable Workflows 3D
tem,” explains Martin Blanke, an AM proj- ect engineer at DMG Mori. The primary goal of the project: develop a lightweight design with the same external form factor as the original assembly but with a reduced number of components and weight, which meant finding a way to maintain the original structural profile while removing as much material as pos- sible from the interior.
Early in the design process, Blanke and his team decided on variable shelling and latticing as the best way to reduce the original design’s weight. However, per- forming these tasks in a timely fashion would be nearly impossible using tradi- tional CAD tools.
Blanke explains: “With our traditional CAD system, it was only possible to shell this component with a constant thickness of 2 or 3 mm, but we found our solution in nTopology.”
nTopology’s field-driven capabilities helped Blanke and his team overcome this bottleneck. Their process:
• Color-code all surfaces of the original design in CAD, each color corresponding to a different subsystem and later used as an input parameter in the topology- optimization software to determine the thickness of each section.
• Import the CAD file in nTopology and shell each section before combining them
into a single body. The thickness of the outer shell was driven by topology opti- mization to maximize its stiffness.
• Fill the interior volume with a confor- mal lattice to increase the part’s structural strength and create a support structure for AM. Using nTopology’s engineering sim- ulation tools, the team rapidly iterated to select the optimal lattice.
Design Automation with Color-Coding
Instead of just designing a one-off light- weight component, the design team devel- oped a robust and reusable optimization process. It based the reusable workflow on the color-coded surfaces of the import- ed CAD body. First, the team defined col- ors for the surface of each subsystem in an external CAD system: blue for the pneumatic inlets and outlets, yellow for the pneumatic channels, red for the inter- faces with the robot, purple for mounting points, green for contact surfaces, and white for the external surfaces.
It then used the color property in nTopology to select relevant surfaces and develop a reusable workflow. If the input geometry changed in future iterations or other projects, the team would only have to import the new CAD file and the opti- mization process would automatically rerun.
An essential design requirement: The external form factor of the original design needed to remain unaltered. The same restriction applied to the contact points with the arm and end effector, the pneu- matic system’s inlets and outlets, the mounting screws for the electronics, and the cabling holes. While topology opti- mization could not be used directly as the final design, the team used the topology- optimization results to drive the thickness of the outer shell.
Using the color-coding system, the team automatically defined the design space for topology optimization. Then, the optimization-process result was used as input to create an outer shell of variable thickness, adding material where required.
“A big advantage of using nTopology,” says Blanke, “is that it’s possible to convert the result of the topology optimization into a useful model that can be used either directly or indirectly in another function.”
This process helped the team grasp some of the structural benefits of topology optimization without changing the part’s exterior.
With the exterior shell developed, the team turned to the structural and pneu- matic systems, also seeking to reduce their weight and integrate them into the design. Using the color-coding system, Blanke’s team easily was able to apply a different
Designing the new metal-AM robot-arm component, the DMG Mori team first color-coded all surfaces of the original design (a-b) in CAD, each color corresponding to a different subsystem and later used as an input parameter in the topology-optimization software. It then imported the CAD file in nTopology and shelled each section (c) before combining them into a single body. Lastly, it filled the interior volume with a conformal lattice (d) to increase the final part’s (e) structural strength and create a support structure for AM.
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