Dynamics CDR Notes

Harshit:

CDR Overview - Harshit

For unsure truss solver do some hand calcs b/c that can help figure out if things are correct - Parra
Can also try putting the truss solver in Ansys to see bending - Robert (need to talk to him more about this)

Suspension Overview and Pushrods - Kayla

Is there a reason for designing for less travel in the rear than the front? - Philip
- Traditionally one wheel rear solar cars have smaller max - Kayla
  - Less Inertia in the back - Jacob
Order of parts bottoming out - Philip
- First was top shell - Kayla
- 2.5 in bump max in shocks
- Make sure there is a bump stop or make a bump stop for the shocks to limit the travel, otherwise you have to do something with the upright to do that - Nathanial
- Assume it can bottom out if needed to
Uphill climb and gravity shocks - Philip
- Chose the uphill shock because more tunability in valves of the shocks and packaged better with our stack - Kayla
Tolerancing issues - Philip
- Just things we seem to see have a tolerance like welding - Kayla
What is the acceptable tolerance error for connection to frame - Jacob
- Might be worth to look at degree of free with rod end (1 degree) seems scary - Leo
- Make sure to check the interference of the spacers - Nathanial
What are we trying to get out of showing the graphs? - Philip
- What is a good amount vs negligible amount of bump toe? - Kayla
- Mainly a reason to show changes from before
- Bump toe seems good, 2 degrees is good - Robert

Shocks and Bellcrank - Andrew

Rot pot may be able to be done cheaper - Jacob
Exploring putting rot pots on the pivot of bell crank - Nathanial
Purpose of sensors - Parra
- How much we think it will travel vs how much it actually travels - Andrew
- What does this inform and what does it help change in design for this year or future years - Parra
- Can use this to double check our calcs - Andrew
- Our attempt at collecting data, shock is traveling wheeling - Kayla
- How is that informing our design? - Parra
- Put some more thought into the shocks and if we actually need it because if you don't really need the data then why spend time and effort in it
Bellcrank feedback slide - Parra
- Preload on thrust bearings, yes
- Depending on the bolt you choose is going to be relatively soft seal, you are going to very quickly bolt past the yield of the bearings
- If you can get a non-threaded shank then great but it's very hard to find the actual non-threaded shank - Nathanial
- If we are adverse to machining the shaft we can buy a precision ground shaft for bearings. Def worth to save time because getting that ground shaft is going to be very hard if you make it in house - Parra
Suggest linear pot - Robert
- Look back at video for reasoning
What was intention with snap rings - Nathanial
- Need to look into the ultra low clearance snap rings
- Could
Greece your bearings - Parra

Pushrod

Compressive loads will cause more things than just buckling but the tearing of the fibers around the insert - Nathanial

Control Arms - Oliver

Jigging for control arms, how are you planning on jigging the control arms - Jacob
Quite a lot of bending stress on the ends of the CAs, can be done a hand calc on the apex
How are you constraining plate for push rod? - Philip
- Consider not doing 3D prints because they will just melt, would be better to do metal parts - Leo
Look into laser cutting or water jetting the parts instead of manufacturing in house because of timelines
Sim for control arm - Jacob
- Everything should be in the z-x plane for bending, unsure about the setup
- Fixed translation
- Lower control arm, pushrod can constrain rotation
- Fixed translation on the two ends and then fixed translation at pushrod mount
- Beam element bearing to bearing
  - Get reaction forces at the upright mounts
- Remote force to contact patch
Staking bearings are much faster - Robert
- Used Arora in the past for bearings and can make it faster and decrease uncertainty
- Might have to China some parts because precision because you need 1/10th precision for housing
- Staking is overall going to be much faster and won't take many weeks of man hours to get it done
You should be trying to constrain your HDPT locations instead of the angle of your control arms - Parra
All the sim stuff talk to Parra afterwards - Parra

Trailing Arm - Jonathan and Manas

Not great to sim lugs (bolts) - Parra
Draw a FBD to solve for trailing arm, one lug is in bending you can hand calc it
Add a centering feature
Putting bolts in bending very bad, suggestion put the bolts 90 degrees to what it is
Good choice in not welding
Shear of bolts in braking lots of preload and having threads in shear plane
Considered the bolts but not the flanges, don't FEA bolts
You transfer the weight forward when you brake because you have no lateral load transfer - Chris

Intro Steering - Evan

Lower Steering - William

At max steer it's basically perfect Ackermann - Robert
Why do we want to be able to take the rack off? - Parra
- Seems like too much complexity and why can't we change the way belly pan is mounted to make it easier regardless
- Overall find a better way to mount belly pan so that we can service under it
Don't sim bolted joints - Philip
Shoulder to extender part why change material rather than change geometry
Need to add helicoil to any aluminum threaded hole

Upper Steering - Joshua

Why put so much effort in trying to sim something you are hand calced? - Philip
For the aluminum contact with the needle roller that aluminum piece will get torn through - Parra
- Switch to some sort of hardened steel either machine in house or look into Misumi as they have sleeves that are designed for this exactly
Any bearing contact must add lube
Take a look at shaft seals

Intro Unsprung + Axle - Sami

Hubs + Brakes - Sohan

Hub FEA - Harshit

Upright - Sumi