Truss Design Challenge Experiment - Group 4

thingiverse

Experiment Description For this experiment, the students in the lab were required to design a truss or bridge to span a specific distance and resist a 100 lb load in a four point flexure test. All the requirements for the bridge are shown below: • Span length of 400 mm • Width of 75 mm • Maximum height of 75 mm • Maximum weight 100 grams • Must hold 45 kg (100 lbs) • No adhesion (glue, etc..) for connections The challenge for the student in this experiment was their bridge had to be printed in separate parts because the bridges were to large to print all at once. The students had to design connections for these parts without the use of glue or other adhesives. The connection design was critical because that is the weakest points on their trusses. Information on Group 4’s Bridge: This is the design from Group 4 in the laboratory. This group decided to design their own truss for this experiment. They took inspiration from the Warren and Howe truss for their design. This group had a more complex and asteticallying interesting design with a total of 7 parts. Their intent with the taller midsection was to resist the high moment acting at the midspan of their truss. The bridge had a total weight of 85 grams and resisted a load of 60 lbs. The truss failed due to the tall rise at the midspan. This tall midspan caused the bridge to overturn laterally during testing because of the larger lateral moment arm acting on the truss at this point. The group recommended to increase the thickness of the members at midspan or simply shorten the height of the midspan to improve the truss design. Note: The handout for this experiment will be available soon. I will provide a link to the handout in this description when it is complete, so you can perform this experiment yourself or with your students.