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Credits
I did not come up with this on my own, in fact I just copied and pasted the vast majority from the mech leads design sprint. So huge shoutout to Aidan Lehal, Min Qian Lu, Kevin Bui, and Emily Guo!!! They did an amazing job getting this together, I only made a couple changes to help make the process a bit smoother.
Sprint Goals
Get members accustomed to designing relevant components and critiquing each other’s work.
Making self-driven decisions throughout the entire process, starting from basic requirements + constraints, to selecting OTS components, all the way to sim validation.
This is very important as we anticipate to be designing with little direct supervision (i.e you can rely on leads so much; being able to think critically for ourselves is huge).
Getting comfortable with holding each other accountable to our own deadlines.
Documenting our progress and decisions.
Topics to be Covered
Force Analysis (hand calculations)
Geometric Analysis (more complicated hand calculations)
Off the Shelf Part Selection
Concept → Design
Material and Manufacturing Selection
Sprint Introduction
We are challenged with designing the bellcrank, bellcrank clevis, and pushrod for the inboard suspension pictured below. The given parameters are as follows. Requirements and constraints will be at the discretion of each person.
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Specification | Value | ||||
|---|---|---|---|---|---|
Shocks from MSXIV | Spring Force: https://www.ridefox.com/family.php?m=bike&family=floatx2 | ||||
Chassis and Suspension Geometry (assume the chassis and control arms can withstand the loads already) |
Made in Solidworks 2019; hopefully there won’t be any issues with backwards compatibility. Shock Info: https://www.ridefox.com/dl/bike/my22/605-00-253-FLOAT-X2-Tuning-Guide-revA.pdf Shock CAD Model: https://grabcad.com/library/fox-float-x2-factory-2019-8-75-x2-75-mtb-bike-rear-shock-1 | ||||
Mass of Vehicle | 192kg | ||||
Center of Gravity Location |  | ||||
Loading Conditions |  | ||||
Assembly Max Height | Final bellcrank, clevis, and pushrod assembly should not exceed 100mm past the top or bottom chassis members. |
Timeline
Note that independent reviews with leads and other members throughout this entire period are encouraged! You are not limited to just the scheduled reviews!!!
Phase 1 [Feb 5 - 19; ~2 weeks] - Review Feb 12 & Feb 19 @ 3:00PM EST
Phase 1 is all about getting some of the thoughts on how to solve the design, along with some of the key constraints/considerations to get ready for detailed design.
Conceptual Design: Sketches of design concepts, with labels and descriptions where needed to effectively communicate design ideas.
Force analysis: Using the diagram of force locations on the model car above, find the center of mass/gravity (CG) for the vehicle, use the CG to determine the load distribution between axles, use the load distribution to find out how much load each independent suspension assembly needs to withstand, calculate how much load each component in your design undergoes based on the front left independent suspension load force.
Kinematic Geometric Analysis: Using different conditions, mathematically determine the optimal geometry of the parts to minimize forces experienced by the shock and chassis. Tie this into the force analysis to see what the shock needs to do in relation to the forces experienced by the tire
Off the Shelf Part Selection: Ensure that your sketches and designs include what types of off the shelf (OTS) parts you would like to use (e.g. You want to join two components together without welding? What type of fastener will it be? Will you use a pin? Shoulder Bolt? Zip tie?). In Phase 1, the selection process does not need to be specific (diameter, thread length, head type, etc.), but these factors should be considered when designing.
Phase 2 [Feb 19 - Mar 05; ~2 weeks] - Review Feb 26 & Mar 05 @ 3:00PM EST
Phase 2 gets into the nitty-gritty of the design. What dimensions do all the parts need to be? What materials? How are we going to make it? Is it cost effective? And plenty more questions. Hopefully by the end you have a fully designed suspension system that hits all the checkboxes.
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In the middle and at the end of this phase, the participants should get together and review each others work, providing advice, feedback, and expressing issues they have experienced along the way.
Sprint Deliverables
The review sessions will be held to share ideas, get feedback, and inspire your teammates! The following deliverables should be presented in a Slide Deck**
TO BE COMPLETED FOR FEB 12: 3 Concepts sketches with details labelled and OTS parts (not specifics)
TO BE COMPLETED FOR FEB 19: Force and kinematic geometric calculations complete for one design.
TO BE COMPLETED FOR FEB 26: Detailed design (CAD) of one sketch with refined OTS parts and material selection.
TO BE COMPLETED FOR MAR 05: Manufacturing methods and some FEA on the Bellcrank and Bellcrank Clevis.
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https://www.icloud.com/keynote/076I-a9-DNFU-WY12J4m1eiAQ#Kevin_Bui_FYDP_FDR - Password is “midsun”
Appendix
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