russ Design Challenge Experiment - Group 5

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 5’s Bridge:
This is the design from Group 5 in the laboratory. Their truss design is commonly known as a Warren Truss. This group had an intermediate design with a total of 4 parts. Their designed focused on resisting overturning failure with their top and bottom cross braces in the middle as well as braces at each corner of the truss. The bridge had a total weight of 92 grams and resisted a load of 85 lbs. This bridge did not experience a failure but was difficult to test due to the rounded ends on the nodes. The loading bar would slip off the round nodes during testing before the maximum load of 100 lbs could be reached. The group recommended creating a flat platform on the top of the truss at the nodes to improve the design of the truss.

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.