An apparatus to measure force in a simple truss system

A simple bench-top apparatus has been developed to experimentally determine the forces in the members of a simple truss system. The device is notable in being an inexpensive stand-alone device, which is easily constructed. The truss is a fundamental design element in many structures. There is a need for a low-cost truss experiment which allows first or second year engineering students to compare theory with experiment. While the truss is a simple structure, obtaining convincing agreement between theoretical predictions and experimental measurements requires careful design of the laboratory device. With the apparatus developed, it is possible to obtain experimental measurements of forces in a truss member which agree within a few percent to predictions from elementary mechanics. The apparatus is easy to operate, and is suitable as either a classroom demonstration or a laboratory experiment. The total cost of materials to fabricate the apparatus is less than $100. The apparatus is appropriate for inclusion in freshman physics laboratories, engineering statics, mechanics of materials, or an experimental methods course.