PYRFOROS IV.

The bodywork is the chassis — a foam-core CFRP sandwich monocoque, replacing the previous generation's steel spaceframe and non-structural fairing outright. Laminate properties came from micro-mechanical RVE homogenization of the team's actual epoxy system rather than generic datasheet values, with ply count and orientation tailored to the FEA-driven load state at each location.

The structure was validated across five load scenarios in EPILYSIS (static, cornering, acceleration, braking, and bump impact), with a Tsai–Wu failure check in META returning a minimum reserve factor ≥ 1.0 on every primary carbon layer. That validation — plus the suspension isolating road-shock energy before it reaches the shell (see Section 04) — let the monocoque down-gauge to a 2.1 mm average thickness. Every CFRP-to-aluminium joint (clevises, mounting brackets) carries a fibre-glass isolation layer against galvanic corrosion, validated to a safety factor of 3.

The shell is laid up regionally, not uniformly: four different stacks assigned by region, an extra twill ply where the handles and local reinforcements sit, the core dropped where it would be pierced, and an aluminium 6061 layer embedded only where the suspension attaches. The monocoque case study sets out all four stacks, the five load cases with their magnitudes, and why the material properties were homogenised rather than looked up.

The previous generation ran rigid and un-sprung, transmitting vertical impact loads over 4.5g straight into the chassis and forcing an over-engineered, heavier layup to avoid delamination. PYRFOROS IV replaces that with a double-wishbone front / trailing-arm rear system on a clevis mounting interface, acting as a structural low-pass filter: peak transmitted chassis loads dropped 65%, and on-track coast-down testing measured a further 12% cut in rolling resistance on uneven surfaces. The platform can be re-tuned for a different circuit surface by hardware alone.

The suspension loads trace to a documented derivation, and the dampers to a shock dynamometer rather than to a catalogue — five rebound and gas-pressure settings, 118 to 191 J of energy dissipated per cycle across the range. The suspension case study carries the input loads, the joint-by-joint resolution, the damper characterisation and the steering geometry, including which parts of the steering work were a teammate’s.

The wheels moved from heavy aluminium rims to CFRP, but the rim and wall aren't a from-scratch PIV design — they're the Master's thesis wheel carried over unchanged: same ER-25S2xx drawing series, same tyre, hoop and wall masses identical to the thesis part to the gram (278 g and 284 g). Only the central hub was revised, to package the belt final-drive pulley and PIV's own mounting interface. That's a stronger claim than an in-house build for this car alone — a CFRP wheel structure designed and validated on one vehicle, adopted unchanged by a different team on a different platform, and re-validated to the same Tsai–Wu reserve-factor standard as the monocoque under PIV's own transient bump-load case, with rotational inertia rather than mass alone driving the analysis: spin-up losses are invisible to steady-state drag but real under the circuit's compulsory stop-and-go. The drive motor's mechanical design and the 6:1 belt drivetrain around it are covered in their own case study.