The S.T.E.M. Program mainly focuses on factors of education that are based upon engineering and design degrees. This project was to test our ability to create and build a bridge out of popsicle sticks that met certain criteria. Engineers need to be able to do this all the time. Bridges help people, cars, and all other kinds of vehicles of transportation get from one place over another thing to another place. They help people cross over roads, water, and sometimes they just serve as decorative pieces that can still function and hold a lot of weight.
Research
The type of engineer that designs and build bridges are civil engineers. They have to be able to design a multiple of different bridge types. The four major types are:
There are four forces that act on a bridge. Compression is a force that pushes objects together. Tension is a force that expands, lengthens, and pulls things apart. Shear is two structure that are forced in opposite directions. Torsion is the twisting of an object due to force.
The students had to design a truss bridge that could withstand 100x its weight out of popsicle sticks.
Tools
We were given three different computer applications to aid our drafting and building. Those three applications were AutoCADD, Autodesk ForceEffect, and Westpoint Bridge Designer. AutoCADD is a computer aided design and drafting application for 2D or 3D structures. Autodesk ForceEffect is an application on Google Play that does all the simulation and engineering calculations for you right on a mobile device. Westpoint Bridge Designer is an engineering game and virtual bridge simulator that has you build a design for a bridge at the lowest possible cost.
Design
My original design was a truss that included three different layers of trusses all arranged in an arch formation. It was a howe truss on top of another howe truss on top of a warren with verticals truss on top of a pratt truss with arch attributes with a camelback truss-like arch. The two howe trusses were designed to even distribute the force of compression to the sides, the warren truss was to balance it out between all of the beams of the bridge, and the pratt truss was to center to force of tension into the middle of the bridge.
Building Process
The bridge was made out of popsicle sticks, hot glue, and wood glue. We had to cut angles in the popsicle sticks for the interlocking triangles of the truss at 60 degrees each in order to create equilateral triangles. It took two weeks to fully complete the bridge.
Each horizontal beam of popsicle sticks had a row of normal popsicle sticks glued together with hot glue, then a layer on top and a layer of popsicle sticks on bottom attached with krazy glue. Each angle for the triangles and the vertical popsicle sticks were attached with hot glue and measured to fit the AutoCADD drawing.
After a few sessions of building, my partner and I realized we wouldn't have enough time in class to complete the two halves of the bridge that we needed. I took the rest of the supplies home and completed the second half there. Later, my partner attached the two halves together by creating T's of popsicle sticks and hot gluing them onto either half of the bridge.
Performance
In order to get full credit for the bridge, it had to hold 100 times its weight. My bridge was 14.7 ounces, so it had to hold 67.5 pounds. Sadly, it only held 65 pounds before it broke. The bridge broke in the crevices of the angles of the middle layer's triangles. The triangles created were not strong enough to hold all that weight on top of it. If I were to build the same design of bridge again, I would use wood glue instead of hot glue in order to attach the angled popsicle sticks.