(from hand analysis to implementation)

Stress Analysis - Design Project

Team Members: Irene Lee, Taisha Vargas

(Course Layout: Wooden obstacle blocks path.)
Performance: Our group placed 1st at the Second Design Review, at which point we were excused from the remaining reviews. Sometimes I question whether my teammates were more excited about the project or taking selfies with the professor. Either way, Taisha and Irene are very talented and fun to work with, and I look forward to doing future meche design projects with them!

Design Iteration

Components which allowed us to knock the total mass down to 7.3oz were minimizing torsional moments at the lifting arm and using a thin u-beam with a minimal number of supports at the base. 

Mitigating Torsional Deflection: Early on there were torsional deflection issues with the u-beam. While the u-beam does well to inhibit vertical deflection due to bending, its gap leaves it susceptible to torsional deflection. To mitigate this issue, the lifting arm attachment was fixated directly below the beam, such that the load didn't induce a moment in either direction. This solution allowed us to successfully implement the lightweight u-beam.

Minimizing Number of Supports: Through iteration we observed which supports were and were not contributing to supporting the load. We found that our struts supported a great deal of compressional force and performed well to resisting the downward vertical deflection. The supports farther behind the struts are in tension, and resist a tendency for vertically upward deflection in the u-beam.

Objective: Build a mechanism which extends past the obstacle without contact, and lifts the cylindrical weight 2in. Mechanism will be powered by a provided servo and may fixate its base with the two clamps provided. Competition - build the lightest mechanism.

Analysis: Our design involved a minimalistic base, with a u-beam extended to support our servo actuated lifting mechanism. To ensure our preliminary design worked on paper, some hand analysis was done for the forces acting along the supports, deflection of our u-beam, and range of motion for our lifting mechanism.