Define the problem
One goal of the project is to construct two different trusses with different amounts of beams and joints. Another goal is to solve for both trusses. A third goal would be to test both trusses to see how much force can be applied before they break.
Generate coNcepts
The break point on the first truss was expected because the force on both sides of the triangle was equal so it was estimated that it was going to be either the left or right side of the triangle. We estimated that the force the truss would be able to handle would be high since we used a stronger type of wood. Our estimate was around 25n of force. The truss ended up holding 53.31n of force. This was over two times more force than we predicted. The design was statically determinant so it was stable and it could hold a load without collapsing.
The breaking point of the truss was not what I had predicted. I had predicted that it would break on the center vertical beam since it was under a high amount of pressure in compression and the load was being applied directly above it. But, it had snapped at the point in the top left part of the truss when it was tested. The max load it held was 7013.0 grams. Since we had used a stronger type of wood, we had predicted it would hold a lot of force, around 35 n but it ended up holding 68.7 n. The design was statically determinate which meant it was stable and it was capable of bearing a load Without collapsing.
Develop a solution
The force values for the beams are slightly off due to the way I rounded my values during solving.
Construct and test a prototype
Truss 1- max force held in grams: 5439.8g
Truss 2- max force held in grams: 7013.0g
Evaluate solution
The first truss is better because it has a higher efficiency than the second truss. The first truss has an efficiency of 3400 while the second truss has an efficiency of 3049.1.
Present a solution
This was the beginning process of constructing the second truss. Only a few of the beams had been hot glued together.
This was the second truss fully completed before testing.
This was the first truss fully completed before testing.
Conclusion
For the first truss, I think failure occurred where it did because the side was under a lot of stress in compression. It was the same amount of stress in compression as the other side, so either side was expected to break. The truss broke where the members had the most stress. For the second truss, I think failure occurred where it did because maybe the joints weren’t very well secured. The member with the most stress was member t, the beam that was diagonal going across the square part of truss 2. It would’ve been expected for the truss to break there, but instead it broke at joint D. If I was to redesign the trusses I would put gusset plates only on the joints undergoing tension. I would also use a stronger type of wood and find a different type of adhesive that would keep the joints together better.