House the outboard spherical bearing of the rear upper A-arm and carry the pushrod tab.
A machined part providing the interface between the component and the structure, positioning it accurately enough that the designed geometry is what the car actually has.
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.
Setup 1, bearing fixed: peak stress 32 ksi, yield FoS 2.084, maximum displacement 0.001728 in. Setup 2, arms fixed: peak stress 33.7 ksi, yield FoS 1.979, maximum displacement 0.003479 in. Tab stress validated against a hand calculation for a hole centred in a wall: calculated 18.95 ksi against 22 ksi from FEA. Separate tab study at 0.25 in thickness gave 39.78 ksi and FoS 1.677, and 9.315 ksi with FoS 5.89 for the holder body. A convergence study was run on the fixed-arms setup using a curvature-based mesh with an element size growth ratio of 1.4.
Three-setup mill part with soft jaws.
AISI 4130 steel, 0.1875 in tab thickness. From the cost report drawings and CAD: From the cost report drawings: AISI 4130 Alloy Steel (CR25_SUS_RLUpperAArm_Steel_FreshProj).
Fault Vault, CR26I, Potential Failure: upper arm ball joints became loose within the housing and had vertical compliance, theory being excessive staking force. A pressure gauge on the pneumatic press is the proposed control.
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. CR25_SUS_RLUpperAArm_Steel_FreshProj (as drawn): 9.40, R0.94, 72.25, 7.23, 3.18, 0.32, 72.447.24, 6.35, 0.63, 2.41 CR26I_RearUpperBearingHolder (mm): TRUE R7.9, TRUE R11.7, R7.5, R2.4, 54.4, 55.3, 19.1, 9.5, 30.8 Source: Cost report drawings: CR25/Suspension/Management-Comp/Cost Report/Drawings/Sus Shocks - Rear A-Arms/CR25_SUS_RLUpperAArm_Steel_FreshProj.pdf; CR26i/Suspension/Competition/Cost Report Drawings/Suspension and Shocks/Rear A-Arms/CR26I_RearUpperBearingHolder.pdf Quantity per car, as costed: 2
Nothing in CrimsonStorage covers these yet.