[Manta Ray - Solar Car]
[Manta Ray - Solar Car]
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Currently serving on UCSD's very own solar car team as mechanical lead and co-president. Very similar to FSAE, but with a focus on energy efficiency over speed and track performance. Designs must be light, and fit around an Aerobody that reduces drag and maximizes surface area for solar panels. The components must be sufficiently strong to endure long road trips, as the race we aim to qualify and compete for is the American Solar Challenge, and is 1500 miles across the US. I have grown the team over the past two years from ~10 to ~50 active members. This will be more like a blog and documenting things as I approched them, so earlier things will change and you will see how I learned alot about design. Eventually will push my other project managers and members to make their own blogs and documentation so we can tell our story as a whole, and maybe help budding teams in the future.
Making a solar car from scratch is no easy task.
Suspension front final design completed and passing extensive FEA. Made with a combination of Solidworks and Fusion360. FEA done with integrated tool from Fusion 360. I focused on making it easily fabricatable and cheap, while also having acceptable handling. More FEA Screenshots below. I have also started a full assembly of the car, integrating subsystems. This was done in Solidworks, and imported back into fusion as a ridgid body. The rear suspension is a placeholder, just a mirror of the front. Still waiting to confirm which motor we are using and it's dimensions. W.I.P PVDR Report
Utilized Solidworks to make the full assembly of the car. Mock up of the front suspension and steering system. This was an old version. You can see how the steering tie rod was moved lower.
update: modified initial suspension design to sit on a bellyplate, Made the cad model much more accurate to real components. Components bought, waiting for the chassis to finish construction. Helping weld and jig the chassis but much love for Ivan and Dylan putting in the hours on that thing. The front ballast also sits in front of the rack and pinion, balancing out the weight distribution from the battery box in the rear.
Initial steering column design. The length and angle subject to change. The force to turn the wheels was calculated to be ~30N, using this source as a reference. No need to change to power steering. Need to figure out what is most comfortable. for driver, as well as pedal position next.
Fall 2025 update - Handed off Steering PM position to Carson Ly, and Suspension PM to Dante Hernandez. Will still be serving with decent oversight as Mechanical Lead, but will be focusing on more design and analysis, while they refine the original designs further and focus on fabrication. First order of business is to help the battery box team with their FEA. Guidelines are that we must prove it will not break free in collision. I also updated the full assembly during this time. Now includes bellypan, steering, seat and seat mounting, Battery box and it's mounting points as well.
First attempt used the assembly as a whole, without assigning specific materials in order to test convergence and boundary conditions. This is also my first time using Ansys for solar car, I have been using it a lot at my internship. The highest stresses were on the bolt holes of the plywood base. All contacts were not explicitely defined but this helped guide me to the right solution.
Now will focus in on plywood base. Modeling it as 7 layers of bonded oakwood.
Acceleration force of 5G, based on worst case for chassis impact. Compression only supports on bolt holes, and remote point mass scoped to face calculated from summing all electrical components (thanks Sean). Weak springs were turned on, had minimal effect
Final results. Stress is low, but next step is to get a physical test rig to tensile test out specific plywood. Does it have enough strength to withstand these loads? Need to test longitudinal and laterial strength as it is anisotropic. A real wood plank would be strong enough though, using ultimate strength as a criteria.
2026, Spring - Back in person and at school after 6 months at Energy Recovery Inc. Jumped straight into rear suspension design. Incorporated 2 new meeting times that run from 7pm - 1am, as I'm running out of time and I want this car done before I graduate and also so we can compete. Meeting our new members was awesome and its nice to see the team so large and close knit after starting from nothing. Starting with redoing the front suspension analysis for new load cases. Now considering a worst case scenario where the car experiences 2G bump, 1G braking, and 1G turn at the same time. The side with the turning force outwards will have the highest stress.
Reaction forces are pretty nasty too (highligted). Upper control arm sees magnitude 805 Lbs, lower control arm sees 1540 lbs. Steering tie rod sees 108 lbs.
Re ran front with new skills and vehicle parameters. Had to design an upgrade package for all the components.
Re designed front suspension. Considered combined loading now and got nasty results at first. Made a comprehensive upgrade package to all the components in order to pass this new challenge with FOS minimum 1.4. Gussests, additional plate reinforcements, and welded in pins to maximize strength while making sure it is possible for us to reuse the parts I designed and that the team fabricated earlier.
Chassis shock attachment is now 14Ga. There is a pin welded in to increase strength and make fabrication/jig easier and more precise (machine cuts holes). Front kingpin now has a reinforcing plate on top of the spindle (part that sticks out for wheel). We still have enough clearance as we are changing the brake system to have 2 caliper up front, but using a thinner brake disk. It's a different color since I modeled it in Solidworks, but our team stores files in Fusion.
Front Arms will see more reinforcements. Both will use a reinforcing sleeve welded ontop of the existing pipe connecting the arm to the kingpin. It is a standard pipe, but there is an 8 thou clearance between the two, Hopefully shrinkage and tolerances will make them fit nicely. The analysis for the arms was done by Dylan Lee and Rafael Medina Perez, under my guidance and mentorship with Ansys.
Now on to my Rear suspension finalized design. Had to consider new factors which were including the motor and its mounting provisions, as well as the abscense of the steering tie rod keeping the kingpin from moving side to side. The rear suspension also had to closely match the front suspension in order to keep our track width uniform. This lets us reuse the same aerofairings in development with Ivan Medrano's aeroshell project team, reducing drag and speeding up fabrication and development time. The motor we are settling on is the QS 205 3000W hub motor found here. This means we need a keyway to secure the end of the motor and it's key that keeps it from spinning in place.
Kingpin sees a unique design of a cut out in 4130 steel tubing (0.120") with reinforcements and geometry kept as close as possible to the front's geometry, but now must accomodate a motor with a keyway. Keyway will be cut using wire edm for highest precision, avoiding wear and tear as it moves around. Bolted and welded into the tube to keep it as secure as possible. The upper control arm will use the same design as the front but now turned rod end vertical to reduce side to side motion. The lower control arm is an all new design, drawing similarities to a swing arm style suspension. This should hopefully reduce all lateral movement and increase weight savings. The packaging is strict due to all 4 aero farings having to be the same size (reuse molds). The will be a machined delrin bushing inside, can change to bronze oil insert later if it causes issues during testing. The rear was not evaluated with combined loading. This design was made in a rush, and definitely FM (design for manufacturing). I've also learned how to CNC parts on 3axis and manual bridgeport, and will probably use it for this kingpin.
Here is the analysis. Did not do the upper control arm, since it's worst case loading is derived from the reaction forces coming from the front combined loading scenario. Kingpin is 4130 steel tubing, giving FOS 1.4. Lower arm is about the same, and two different configurations tested. Will probably settle on the 10in long one since shortening the kingpin to accomotate for a shorter arm brings it's stress up to 77ksi, above our yield. Only benefit would be that it would match the front track width exactly, instead of sticking out 1.4in further. Bolts are grade 8, and will experience 47 Ksi pure shear. Some online estimates suggest yield is 90ksi, giving FOS around 2, but will monitor these during testing for other conditions not accounted for such as temperature creep, fatigue, and vibrations. Would love to do vibration analysis if I had more time. Next step is to dive in to fabrication and finally testing the car!
2/6/26 - Taking rear suspension to machine shop. Good chance to brush up on my drawing skills that I learned at ERI
made sure to split up all the reinforcing pieces from the main assembly as well. Will have to fabricate each one and check critical dimensions, mainly the ones relating to the bolt holes. Arbitrarily assigned tolerances, will consult with school's machine shop to get more insight
3/13/26
Things have been moving very fast: I shifted my focus to accelerating the fabrication timeline. The full front suspension assembly was completed and fully welded. I also sponsored a project for the less epxerienced members in order to build a placeholder for the rear, so the steering team could begin testing on the road (powered by electric skateboard clamped underneath)
I also helped fabricate many misc things such as the upper rollcage, a steering wheel adaptor, bellypan, and pedalbox. I am currently the only member on the team able to use the waterjet, which has made my life very busy. Wrapping up the quarter in a good spot, motors have finally been ordered! Changed the rear suspension design slightly and purchased materials. Began manual milling and pipe cutting.
For more information, although less detailed Triton Solar Car Website
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