MATERIALS: 1⁄4"x1⁄4"square balsa wood (Nine balsa woods of 3 ft lengths) and water soluble Elmer's white glue.
RULES FOR SIZE: Bridge Dimensions
| Maximum length |
40 cm |
| Maximum width |
10 cm |
| Maximum height |
24 cm |
| Minimum clearance |
10 cm |
| Minimum span |
25 cm |
| Maximum Bridge weight |
75 grams |
When running a Finite Element Analysis (FEA) the results collected show that the optimized angle for this was close to 130°. The picture below show a deformation scale of 10 for displacement results.
In our optimization test the main goal is to change the angle that the support makes with the horizontal part of the top bridge. This table below show the results we obtain from the optimization. The failed results are values that goes over the ~20 MPa yield strength of the balsa wood used in the experiment. This means the bridge cannot support stresses over 20 MPa. The GREEN column shows the optimized results and any values in the white column are passing but not optimized. Further optimization around 130° can be done to find a better result.
The gif animation below show the various angle that were tested at. Note that while the angle is changing the supporting wood position also changes as well.
You can check out the video of my actual bridge test above.
Please bare with me as this information is outdated and there is only displacement FEA results for now. I have lost my other results such as stress and strain FEA and the other balsa wood designs I have done. It might be uploaded much later when I have the time.