UCR Machine Design Bridge Project
ME 174 Machine Design
The objective of this project was to build a bridge of the teams choosing from straws of unknown properties and accurately estimate the maximum load carried before failure as well as the mode of failure. To add to the complexity only 25 straws were given to each team and although any adhesive could be used to hold the bridge together nothing could be poured inside the straws.
Structural Member Load Analysis
ME 174 Machine Design
The loads in each member where calculated via nodal method. After Identification of the member with the highest load column buckling analysis could be performed in order to determine failure mode.
Structural Member Failure Mode
ME 174 Machine Design
After determining geometric properties such as the slenderness ratio failure method such as Johnson regime or Euler Buckling could be considered. With these calculations the failure position and load where estimated. Additionally other unknown values such as the modulus of elasticity where estimated with a compression rig with assumed cantilever end conditions.
Loading to Failure
ME 174 Machine Design
The estimated location was as predicted being the top most members. Due to out of plain buckling likely caused to uneven gluing of members the bridge buckled to one side and failed at the anticipated member as well as adjacent members.  Actual failure load of 8400g was only off the predicted load by 16%
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