The rear friction surface.
Same full-floating architecture as the front, on a slightly smaller disc since the rear does less braking work.
No part-specific design process is documented. The Brakes subsystem design process applies: 1. Set tire loads at the maximum airspeed seen (90 mph): rear 291.60 lbf at max acceleration, front 454.21 lbf under braking, 427.97 lbf cornering. 2. Sweep master cylinder bore combinations against required pedal force and achievable deceleration, then select. 3. Run a transient thermal simulation of the rotor for a single braking event (2.4 s, 260 C initial, 90 W/m^2-K film coefficient, 0.8 emissivity, 25,375 W heat flux front) and import that thermal load into a static structural run (1.84 g deceleration, 12 MPa pad pressure, 707 N-m moment) with cylindrical and frictionless supports. 4. Compare candidate materials on peak and low temperature and on minimum factor of safety. 4340 gave 741.2 C high, 344.5 C low and FoS 3.6438, against Class 40 cast iron at 490.5 C, 256.5 C and FoS 2.1622. 5. Validate with brake rotor temperature sensors on all four corners and compare measured against calculated.
ANSYS worst case: 35 mph, 810 N-m moment, 27,063 N clamp force, 260 C initial temperature, 90 W/m^2-K film coefficient, 0.85 emissivity, 18,000 W heat flow.
4340 steel (previously Class 40 gray cast iron). From the cost report drawings and CAD: From the cost report drawings: AISI 4340 Steel, annealed (Rear Rotor).
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.
Diameter 6.72 in, thickness 0.1875 in, mass 449.153 g. Rear rotor assembly with ISR 22-049 OC/D calipers totals $352.09 against CR22's $374.68. From the cost report drawings and CAD: Measured mass: 424.5 g average across 2 weighed instances (RL Rotor 418.0 g, RR Rotor 431.0 g), uncertainty +-.5 g. Left-to-right deviation -3.02%. Weighed mass: 418.0 g (0.922 lb), 498.0 g (1.098 lb) (recorded as: RL Rotor). Weighed mass: 431.0 g (0.950 lb), 497.0 g (1.096 lb) (recorded as: RR Rotor). Measured mass, as built: CR25 498.0 g (1.098 lb) (weighed as: RL Rotor). Measured mass, as built: CR25 497.0 g (1.096 lb) (weighed as: RR Rotor). 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. REAR BRAKE ROTOR (in): 170.69, 6.72, 4.76, 0.19 CR22_SUS_R_Rotor_RevFinal (as drawn): 17.07, 0.64, 0.51, 0.95 Rear Rotor (as drawn): 17.46, 0.64, 0.48 CR26I_RearBrakeRotor (mm): 17.5, 0.6, 0.5 CR26I_RearRotorAssembly (mm): 17.5, 2.1, 0.5 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/Document Submissions/Cost Report/Suspension/Cost Report Drawings/Brake System/PDFS/REAR BRAKE ROTOR.pdf; CR22/Suspension/Design/01_Cost_Report/Cost Report Drawings/Brake System/CR22_SUS_R_Rotor_RevFinal.pdf; CR22/Suspension/Design/01_Cost_Report/Cost Report Drawings/Brake System/PDFS/REAR BRAKE ROTOR.pdf; CR25/Suspension/Management-Comp/Cost Report/Drawings/Brakes - Rotor Assembly/Rear Rotor.pdf and 2 more Quantity per car, as costed: 1, 2
Nothing in CrimsonStorage covers these yet.