Balance Bike Frame
(Onshape Hackathon)
Feb 2024
GOAL: design a frame for a balance bike that deforms 4mm under a 200N load
SKILLS: CAD (Onshape), iterative design
In 1 hour, we had to design a suspension frame for a hypothetical adult balance bike design. The frame must allow for a 4mm deflection of the seat under a 200N load.
I got first place with the lowest score and won a backpack--wahoo!
It took me about 190N to reach 4mm, which was second closest in terms of force and deflection, but I then had the lowest weight.
Scoring Criteria
lowest score wins
if you reach a deflection of 4mm before 200N, the difference of th eforce you reached and 200 is added to your score
if you reach a force of 200N before you reach a deflection of 4mm, the difference of the distance you reached and 4 is multiplied by 10 and added to your score
finally, the weight of your frame is multiplied by 10 and added to your score
Challenge
What made this difficult was that the properties of the material and the simulation were not completely accurate. It was difficult to decide whether to try to get close to 4mm, or instead choose a different target distance. Based on the two examples they ran while demonstrating the testing mechanism, I recreated the conditions in the simulation and used proportions to come up with a target deflection of about 3.5.
Simulation
Reflection
One of the most challenging aspects of this, for me, was the time constraint. I spent a lot of time in the beginning trying to decide how I would account for the error in the simulation. I probably could've gotten a lot more information from quickly prototyping 3 designs and getting 3 data points to work from. By the time I realized this, I only had time to make two designs, one as an indicator, and one final. In some ways, my planning paid off because I spent a while considering the different reasons that the simulation might be off. In others, I might've been better off realizing sooner that my planning was still going to have so much error that just jumping in and gathering more information may have been a better use of my time. Because of this, I was the last person to test, so at least I got to have a dramatic win.
