The Truss Tester Accessory for the Vernier Structures & Materials Tester makes testing single trusses quick and efficient. Testing trusses can be a great engineering design project by itself, or you can use it as a building block for designing a bridge or another structure that is comprised of trusses.
I’ve been reading and thinking about trusses a lot lately, but I decided to get my nose out of the books and collect some of my own data. I took my construction skills out of the picture as much as possible and used the corner brackets that ship with the Truss Tester. These are also available for download as a 3D printer file. These brackets really make truss construction a breeze! I simply slid them on the bottom beam of the truss, anchored them in place with a small brad, and cut the rafters to length. I hot glued the rafters together at the peak, although the truss holder tended to keep those parts together during the test. I ended up making five different angles of simple triangular trusses, ranging from 34 to 53 degrees, all with a 21 cm base. I tested each truss, noted the maximum force required for it to fail, and plotted this data.
My data indicate that there is an optimum angle—not too steep and not too shallow. I also observed that most of my trusses seemed to buckle rather than pull apart or push together. In my next redesign, I started with a 40 degree truss angle and added some mid-rafter supports.