The end-to-end mechanical design process for an economical, stiff, strong and aesthetic truss bridge.
Asymmetrical Truss Bridge
Timeframe
Oct - Nov 2021
(2 months)
Team
3 mechanical engineers
Role
design, manufacturing, testing
Scope
end-to-end process to design miniature laminated paper bridge
Tools
SolidWorks, Laser Cutter
Role
While the team contributed equally on most aspects of the project, I had 2 distinct contributions:
I led ideation & concept development. Out of 18 initial designs, my team adopted one of my bridge concepts for its aesthetic appeal and the added challenge of designing an asymmetrical structure. My design achieved the highest score for aesthetics and creativity.
I executed Finite Element Analysis (FEA) in SolidWorks with preliminary and final designs to predict maximum stress and deflection.
I played an equal part in SolidWorks modeling and manufacturing.
Process
Brainstorming > Truss Analysis > Design Iterations > CAD Modeling & FEA > Failure Prediction > Manufacturing > Testing
Detailed Process Diagram
Evaluation metrics & Specifications:
economical (low weight & limited amount of material)
stiff (low deflection)
strong (able to support high load)
aesthetically pleasing & creative
Full Project Report
Challenges & Takeaways
My team was the only team that decided to take on the challenge of designing an asymmetrical truss bridge for our final project. We achieved high scores for creativity, aesthetics, and economical design for the low weight of our structure.
While we predicted the first member to fail correctly, our predictions of maximum load and deflection were erroneous, shedding light on a few key takeaways:
SolidWorks best practices:
We learned the importance of developing consistent CAD design methodologies when working collaboratively. We designed the bridge by building on each other’s work, but did not apply a consistent method, which led to difficulty troubleshooting and delays in our final analysis. In a real-world scenario, I would have optimized the design of our bridge at least another time before manufacturing.
Accounting for testing & real-world conditions:
We learned to more holistically define design constraints. When designing our bridge, we did not account for the importance of aligning compression members with the test support jigs, which we hypothesize would have increased maximum load. In simulation, we were constrained to place point loads at the nodes closest to where the supports actually touched, which yielded different results than the real-world scenario.
We learned to analyze ambiguous design tradeoffs and the importance of prioritization. While optimizing for weight by using different materials for tensions and compression members, we believe we lost some of the potential strength of our bridge. Using the same material would have ensured an even distribution of stress through the members.