CR21 assembly-level line for the rear lower A-arm.
See the Rear A-Arms entry.
No part-specific design process is documented. The Arms subsystem design process applies: 1. Take the geometry points from kinematics and the wheel loads from the load cases: CR26I front outside cornering 648.691 lbf vertical and 786.094 lbf lateral, braking 585.523 lbf vertical and 763.26 lbf longitudinal, combined 768.095 / 785.550 / 444.124 lbf. 2. Resolve loads into each member with Altair HyperWorks MotionView. 3. Size the tubes in the calculator against buckling and yield. CR26I front upper 0.375 in OD / 0.305 in ID at minimum FoS 1.946; rear upper same tube at 2.581; front lower 0.625 / 0.527 at 2.49; rear lower 0.5 / 0.402 at 2.62. 4. Analyse the spherical bearing holder with two FEA setups so the boundary conditions are cross-checked: bearing fixed with loads at the pullrod bolt and arms, then arms and pushrod bolt fixed with a remote load at bearing centre. Validate the tab stress against a hand calculation for a hole centred in a wall (calculated 18.95 ksi against 22 ksi FEA). 5. Weld in the jigging assembly, then measure the finished arm.
None recorded. This part has no entry in Knowledge_Transfer/Issue Logging/Fault Vault.xlsx, in either Issue Log.xlsx, in CR22/Issue Tracking/Shakedown 7-15-23.xlsx, or in any design review issue list found in CrimsonStorage or Box.
Measured mass: 442.0 g average across 2 weighed instances (RL Lower Arm 442.0 g, RR Lower Arm 442.0 g), uncertainty +- 1 g. Weighed mass: 442.0 g (0.974 lb), 458.0 g (1.010 lb) (recorded as: RL Lower Arm). Weighed mass: 442.0 g (0.974 lb), 456.9 g (1.007 lb) (recorded as: RR Lower Arm). Measured mass, as built: CR25 458.0 g (1.010 lb) (weighed as: RL Lower Arm). Measured mass, as built: CR25 456.9 g (1.007 lb) (weighed as: RR Lower Arm). Dimensions called out on the cost report drawings. These are the figures printed on the drawing, not a labelled specification; open the drawing itself for what each one refers to. RL Tab (as drawn): 0.17, 1.45, 0.48, 2.74 Source: CR22 Suspension Component Weights.xlsx (weighed, not CAD) | Subteam weight books: CR22/Suspension/Validation/Full System Analysis/Component Weights.xlsx | CR26e Weight Tracker.xlsx, Final IRL Weights (weighed, not CAD) | Cost report drawings: CR22/Suspension/Design/01_Cost_Report/Cost Report Drawings/Suspension & Shocks/Rear A-Arms/RL Tab.pdf Quantity per car, as costed: 2
Nothing in CrimsonStorage covers these yet.