Truss Construction
Brainstorming
The main idea of this project was to design, build, and test trusses that can hold 100 lbs of force. A truss is made up of triangles and is used for a support for bridges or roof framing. The first thing I did was sketch out a few truss ideas in my notebook. These trusses had to have a length of 7 inches and had to be in between three and 4.25 inches for the height. I chose a truss that was statically determinate. I calculated that it would hold a load of about 65 pounds. I created my truss on MD Solids and found that it should work.
Construction
After making the decision that I wanted to make the calculated truss, I started to build it. We used thin wood material and manila folders for gusset plates. A major problem with building this truss was that the angles in which the members were cut at weren't perfect and didn't fit with each other as well as they should have. The gusset plates also weren't cut very nicely. The glue was left to dry for about 48 hours.
Testing
The truss was placed into a machine that applies force to the top of the truss. The force was set at 100 lbs, and the truss didn't last very long after the machine was started. As it turns out, I had calculated for two sticks to be laminated together which would have possibly doubled the 29 pounds of force that it held.
Results
The truss broke at a member which was suprising to me because the joints weren't glued as much as I would have liked them to be. If I could do this project over again, I would have liked to cut the angles more precisely. Because the angles weren't cut right, the truss was a little too tall which threw the calculations off. Also, I would have glued the joints a little bit better and cut the gusset plates more accurately. The truss would have worked out better if I had used the thicker material I had calculated for. Besides that, I'm glad that I learned from my mistakes well enough to know what I could improve on.