Description
The Additive Manufacturing class at BU imbibed in us design techniques and principles surrounding 3D printing across different materials and processes.
This included both collaborative and solo projects spanning problem statements, dimensional constraints and end objectives
FDM: Bridge Project
Using Creality Ender 3 Printers (FDM, printable bed size: 220mm x 220mm), the teams were tasked with designing a bridge that would:
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Span across a 450mm distance horizontally
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Be simply supported over a flat table
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Bear a weight of 10Kg hung through the center
Considering the limitations on print bed size, the bridge would have to be made as multiple separate components, and would need to be combined using geometrical features or metal pins.
Ideation
The need for assembled pieces on the bridge, the importance of strength to weight ratio pushed us to think of lean designs.
Using generative design software Altair Inspire, problem constraints were used to analyze an organic shape best suited to the load bearing requirement.
This exercise was carried out assuming homogenous thermoplastics (ABS), meant more for topological inspiration than direct end significance.
Generative Bridge Designs
(Design Space: Left, Solutions: Right)
Development
Generative designs suggested an arched shape for utilizing design space for load bearing strength. The height utilization of the arch would help increase stiffness against bending.
We thought of combining the topological suggestion with the idea of identical elements to our bridge. Considering the nature of FDM printing, a design incorporating identical part elements seemed like a good way to assure reliable performance and strength in the overall structure.
The Da Vinci Bridge
The Da Vinci bridge was an ideal candidate for design inspiration. It is known for its light-weight, self clamping design, and is, to day used in many emergency and military applications for temporary bridging.
It also provided the opportunity for creating simple, identical elements to our design which would be more predictable to test and deploy.
Da Vinci Bridge
Prototyping: Scale Model
A simple Da Vinci bridge was prototyped to test performance against a centrally strung weight at a reduced scale.
It helped us identify some key observations:
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It was easily controllable in terms of print orientation and strength
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While the load bearing direction exhibited a lot of strength and rigidity, the bridge, by itself was very weak and prone to toppling sideways due to its simply supported interaction among individual elements
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The semicircular notched interaction among different beams was prone to slipping nd disengaging before structural failure
Reduced Scale Prototype
Improvement and Design Optimization
Even at a roughly 1:2 scale, the bridge was able to sustain about 7Kg of weight at 25 percent Infill. This was very positive news with regards to optimizing the sizes, shapes and infill density towards the target load.
Further design activities included:
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Changing element interaction from simply supported to closed hole and pin design
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Topology Optimization of individual elements
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Testing individual elements with full load to predict overall bridge strength
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Infill testing to reduce overall weight
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Adding an aesthetic theme to the design
Topology Optimization
(Autodesk Fusion)
Aesthetic Theme Addition
Infill Testing
Final Design
(weighed less than 200g)
SLA: Diorama Design
Using Formlabs SLA printers, the project involved creating a creative diorama within a specified volume of 35mm x 35mm x 75mm. The project statement was left to an open-ended creation of something 'breath-taking'.
Ideation
I wanted to create a moving entity within my piece, with a creative element to it. Considering the surface finish advantages in an SLA print compared to an FDM, I investigated simplistic, minimal designs with moving elements to create within the specified volume.
Self Climbing Double-Cone
The self climbing cone is a classic optical illusion that leverages basic principles of physics against illusive geometry to create an effect of an object defying gravity. On a carefully designed path that appears to go upwards in inclination, the Center of Mass of the double cone actually move slightly downward, hence through coupled forces of gravity and normal reaction, the cone rolls spontaneously 'upwards' on the path.
Upwards Rolling Double Cone
I gravitated towards the simplicity and dexterity of this design. Both the track and the cone was printed within the specified volume in a single print job, and the cone was then detached from the remaining geometry and made into a separate moving piece.
Test Piece
Final CAD
Final Piece
(Added a joke about Sisyphus)
Metal 3D Printing
Using a Concept Laser Metal 3D printer, I created a Boston University Terrier based piece. This project exposed me to free form modeling using Blender 3D.
I created a Terrier head statue with a neck collar to print a free standing piece.
CAD Concepts
Final Print