Week 10

Week 10

this week the team worked on finishing up solid work models and conducted FEA on most of them
Through rapid prototyping we were ale to see that our designs had a few problems that needed to get fixed before the final product.

Articulation

• The problem with articulation structure where it would fail when loaded with 2500lb was fixed by adding a small section that helped reduced the moment arm caused by the bearing carriage. Shown in next figure. 

The following figure shows the redesigned part.

• This new design greatly reduces the moment arm allowing the structure to carry more weight.
• This design has a factor of safety of 8.86 this means there is alot we can do to improve the design and reduce its weight from current 14 pounds.
• Since the bogie will not be using an axle we had to think of a new way to mount wheel housing to the new articulation system for now we designed this component which works as a carriage for the thrust bearing and also has mounting holes for the wheel housing.
• 
• This component is made out of aluminum. the others will be made out of 1020 steel
• This articulation uses a series of bearings two flange and a thrust bearing.
• The flange bearings (red arrows) at the top and bottom help keep thrust bearing carriage aligned.
• the thrust bearing (orange arrow)will take any upward forces.
• 

Guide Arm

• Rapid prototyping was done at half-scale for the main spring loaded components of the guide arm. 
• It showed concerns of manufacturing next semester because possible difficult of welding slots
• also, if load is not always perpendicular, another mounting point needs to be added to the end of the slots.
• the Second design solved the issue of failling under the applied forces, and fitting inside the 12 cm gap
• however, the factor of safety was just slightly above 1.
• A third version was design and FEA was done separately on the parts.
• material thickness was increased to 5 mm
• mounting points were moved
• ribs were added to design.
• A spring has also been selected for the design from McMaster-Carr.

 

Emergency Braking System

• Rapid Prototyping is completed at 1/3 scale. 
• Main system in CAD is completed, but will need modification due to some issues
• Bracket for electromagnet needs to be made
• Issues: Need a way to compress spring after the system is deployed. After inspecting the prototype, I learned that the rod inside the slider assembly may rotate during brake deployment. 
• FEA still needs to be worked on after a solid design is made. The updated model needs to fix the issues listed above. 
• Need to decide which material to use. Aluminum will definitely work for Maker Fair, but not sure it will work for the actual design. 
• Spring and electromagnet has been chosen, which can be seen in our last weeks posting.