Rewriting of Bride Lab

docx

School

University of Missouri, Columbia *

*We aren’t endorsed by this school

Course

1100

Subject

Mechanical Engineering

Date

Dec 6, 2023

Type

docx

Pages

3

Uploaded by CorporalLorisPerson977

Report
Bridge Lab Introduction The purpose of this lab was to create a bridge out of plastic that could whistand as much sand as possible. The bridge must cover a gap between two tables that is 18 inches and also must be at least 3 inches in width. We are supposed to keep the cost in mind while creating and designing the bridge. Each different length of plastic cost a certain amount ranging from $3,000 to $7,000. Each plastic joint costs an additional $500. Procedure We began the lab by brainstorming different designs. We decided to go with a design that was made up of small triangles which we thought would make the bridge as sturdy as possible. We wanted to use the least amount of joints thinking that it would allow for our bridge to be stronger and less likely to collapse. We started with building the base making sure it was at least 18 inches. After that we started to build up using small triangles until we created a large triangle that we felt was strong enough to hold enough sand. Our design most closely resembled the Pratt Truss in the end. Bill of Materials Part Quantity Cost Joint 20 $4,000 7.5” 6 $42,000 5” 22 $132,000 3” 2 $10,000 2” 8 $32,000 Total Cost: $220,000 This table is a Bill of Materials that shows all of the parts that we ended up using and their corresponding costs. Under it is the total cost of materials used that was $220,000 Photos
This picture shows a rough sketch of the front, top, and right side views with approximated dimensions. This photo shows a front view of our final design.
This photo shows an isometric view of our final design. Discussion After testing our bridge was able to hold a final weight of 10.6 lbs. It did this while itself only weighing a total of .38 lbs. This resulted in a total efficiency of 2789%. During the test our bridge began to fail at the second joint from the bottom that can be seen in the front view photo on the left side. The plastic stick slipped out of the joint causing the bridge to collapse on itself. We believe this happened because the weight shifted from one side to another causing the stick to shift outwards from the rest of the bridge. To strengthen our bridge where we failed we estimated that it would cost roughly $30,000 more than the current cost. The cost of this bridge today with added maintenance for 50 years would total up to be $1,245,000. Conclusion In conclusion, bridges that include fewer square/parallel beams with no supporting cross members (specifically ones that form triangles) are both more expensive and less efficient. Conversely, bridges that include many small triangles and fewer large triangles tend to be just as efficient while costing more overall. The bridge we built had the lowest cost out of the class while still maintaining nearly 2800% efficiency. This gave us a cost per percent efficiency of $78.57 per percent efficiency. Additionally, reducing the amount of zero force members in a truss while maximizing the member that will experience a compressive force when the load is applied will reduce the cost while maximizing the efficiency of the bridge. So the ideal bridge is one that has larger inexpensive triangles, fewer joints, and as few zero force members as possible.
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help