Tim Wyckoff David Cenidoza Sachin Narvekar Felix Liu Weston Wells Teh Sl4ck0rz!!!1!1 (group 8) Tim Wyckoff David Cenidoza Sachin Narvekar Felix Liu Weston Wells

Table of Contents Project Introduction Component Testing I-beams Prototype Designs (pros and cons) A-Frame design Prototype Test Results Final Design (changes) Final Test Results Evaluation of changes and recommendations Conclusion

A Project Introduction “A-Frame” Bridge This PowerPoint will outline: Why we chose this design Different Ways it can be done How effective it is

Component Testing Fish line Test Tension Testing Tongue Depressor Test Torsion & Bending Test

Compression The test is responsible for testing the integrities of different truss structures, finding it’s strong and weak points Finding the best way to put it all together and maximize the efficiency of the bridges Some of the tests on the tongue depressors involved compression, tension and bending/torsion. To do this we just applied vertical pressure on the depressors with a scale underneath it and read of the weigh limit using visual confirmation at the first sign of bending Box Structure

Torsion and Bending Testing The testing involved building platforms that were different in design, and they were Tested for their strength and flexibility by twisting and bending. The testing was to find out which designs would excel in strength and flexibility, therefore ways that help maximize the strength and flexibility of the bridges can be known. There are many platforms that were designed and it was easy to distinguish which designs provided more strength and flexibility “X’s” into the designs helped with the strength and it wasn’t too flexible

Fish line Testing The purpose of this test is to figure out the amount of tension 4 different fishing lines could withstand. Used four different types of fish lines; 10,20,30,65 65 lb line despite it’s in ability to hold its alleged weight, it still managed to withstand the most tension under the least strain 65 l line is recommended

Tension Testing The test is to determine the amount of tension two tongue depressors could withstand before breaking Three types of glue; super glue, Elmer’s glue and Elmer’s glue wood Popsicles were glued together at three different overlap lengths, which were ¼”, ½”, and ¾”. Elmer’s glue

I-Beam Effective beams with I or H shaped cross-section Commonly use in construction. Strong is bending and Torsion. Extremely Strong in compression (perfect for our side beams).

Prototype Designs: Cable-stay Bridge Pros Lightweight Potential for high efficiency Simple design Cons Not ideal for point loading Weak design

Truss Bridge Pros Very symmetrical Strong Cons Heavy Difficult design Too many meaningless pieces

A-frame Bridge Pros Ideal for point loading Strong Very symmetrical Simple design Cons Pretty heavy Great opportunity for torsion

Why the A-Frame? The A-frame bridge has a very strong, supportive design. It is ideal for point loading, which is how these bridges were being tested The design is very simple and does not take long to assemble. Picture of Prototype

Prototype After Testing Prototype Results Weight: 0.656 lbs Max. Load: 181 lbs Score: 276 What went wrong? Bridge was not built for point loading Many unneeded beams or tongue depressors Tongue depressors not placed in supportive places Bridge failed mainly due to torsion. Prototype After Testing

Final Design Changes we implemented Making side beams touch in the middle by changing the angle Turned all beams into I-beams Added middle I-beam Used fewer tongue depressors Made bridge more stable (even sides, less wobbly)

notice the bottom right corner Final Test Results notice the bottom right corner Weight: 0.58 lbs Max. Load: 379 lbs Efficiency: 654 What Went Wrong? Some torsion along bottom beams Weak base-side connection Use of hot glue instead of Elmer’s.

Side by Side Comparison Prototype Final Design Before After

Final Word Angling of side beams = Success Omission of diagonal beams = Success Addition of middle I-beam = Partial Success Recommendations for more improvements Maybe take out middle beam Strengthen base-side connection

Conclusion Overall: Success Results: Efficiency: 276 -> 654 Did well on original goal of building a tongue depressor bridge that held maximum amount of force, with minimum weight. Results: It is important to give direct support to wherever the point loading is applied It is extremely important to build your bridge precisely and carefully (make precise measurement, glue well, etc.) Connecting Parallel beams gets rid of torsion Don’t use pointless beams and tongue depressors. Having a lighter bridge really helps