Building Bridges
Mechanics of Solids and Structures (MechSolids), Spring 2014
As part of the final project for the class, Mechanics of Solids and Structures, there were two bridge building projects: the first was built out of spaghetti and the second one built out of tongue depressors (popsicle sticks). In both final projects, each team of five students was required to mathetmatically predict the performance of their bridge in terms of breaking strength, magnitude of deflection before breaking and strength to weight ratio. Each team then built their and, at the end of a week of building, a bridge contest took place where each team's bridge was loaded to its breaking point. Each team then had to write a report detailing their findings and the closeness of their mathetmatical predictions to actual bridge performance.
Both of the bridges built by me and my team are shown below and the final reports can be found in the corresponding section for each project.
Both of the bridges built by me and my team are shown below and the final reports can be found in the corresponding section for each project.
Spaghetti Bridge
The first was the spaghetti bridge project. Because we wanted a challenging and non-conventional design, my team chose to attempt a design utilizing just a single arch instead of the conventional bridge design consisting of two arches joined together along the circumference to form the truss of the bridge. The pictures below are pictures from the design and building of the bridge. Below the pictures, you will find a link to the final report.
In the end, the data for our bridge showed that we were able to predict the load that would break the bridge to within 17.4% (actual breaking load of 16.94lbs instead of the predicted 20.5lbs) and thus, we were also able to predict the strength to weight ratio of our bridge to within 17.4% as well (actual strength to weight ratio of 22.83lb/kg instead of 27.63lb/kg). Remarkably, we were also able to predict the precise point that the bridge would break.
In the end, the data for our bridge showed that we were able to predict the load that would break the bridge to within 17.4% (actual breaking load of 16.94lbs instead of the predicted 20.5lbs) and thus, we were also able to predict the strength to weight ratio of our bridge to within 17.4% as well (actual strength to weight ratio of 22.83lb/kg instead of 27.63lb/kg). Remarkably, we were also able to predict the precise point that the bridge would break.
Popsicle Stick Bridge
The second project was the tongue depressor (popsicle stick) bridge project. This time, however, my team chose to prioritize ease of fabrication. Hence, for this project, we chose a more conventional truss design for our bridge. Becuase of the increased complexity with this design, we were unable to use solidworks to obtain simulation results for the performance of our bridge. Thus, all predictions were made using hand calculations and estimations only. The pictures below are pictures from the design and building of the bridge. Below the pictures, you will find a link to the final report.
Despite our choice to prioritize ease of fabrication, we now had a design that unfortunately was too sensitive to manufacturing inaccuracies. As a result, we failed to reliably predict any of the prediction criteria but learnt alot about the allowable tolerences in manufacturing. For more details, see the report at the link below.
Despite our choice to prioritize ease of fabrication, we now had a design that unfortunately was too sensitive to manufacturing inaccuracies. As a result, we failed to reliably predict any of the prediction criteria but learnt alot about the allowable tolerences in manufacturing. For more details, see the report at the link below.