Mitigating porpoising through variable stiffness suspension in ground effect motorsport cars
Porpoising in ground effect motorsport vehicles represents a critical aerodynamicstructural coupling phenomenon that limits performance and compromises driver safety. This research investigates the application of passive variable stiffness suspension systems to mitigate porpoising oscillations while...
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| Tipo de documento: | dissertação |
| Data de publicação: | 2025 |
| País: | España |
| Recursos: | Universitat Politècnica de Catalunya (UPC) |
| Repositório: | UPCommons. Portal del coneixement obert de la UPC |
| Idioma: | inglês |
| OAI Identifier: | oai:upcommons.upc.edu:2117/449415 |
| Acesso em linha: | https://hdl.handle.net/2117/449415 |
| Access Level: | Acceso aberto |
| Palavra-chave: | Aerodynamics Automobiles -- Dynamics Automobiles -- Springs and suspension Ground effect aerodynamics Aerodynamic-suspension coupling Dual-rate torsion bars Vehicle dynamics simulation Racing suspension technology Oscillatory instability control Aerodinàmica Automòbils -- Dinàmica Automòbils -- Ressorts i suspensió Àrees temàtiques de la UPC::Enginyeria mecànica |
| Resumo: | Porpoising in ground effect motorsport vehicles represents a critical aerodynamicstructural coupling phenomenon that limits performance and compromises driver safety. This research investigates the application of passive variable stiffness suspension systems to mitigate porpoising oscillations while maintaining competitive performance in racing applications. The study employed a comprehensive simulation framework combining Chassis Sim vehicle dynamics modelling with MATLAB signal processing to analyse a validated GP2 2011 vehicle model. Porpoising characterization confirmed oscillation onset at 230 km/h with frequencies of 5.2 Hz during straight-line operation, accompanied by downforce losses exceeding 50% (2849N to 1419N). A systematic parametric analysis evaluated six distinct rear suspension stiffness configurations, ranging from baseline 180 N/mm to negative stiffness scenarios, across critical speed ranges of 230-260 km/h. Results demonstrated that reduced stiffness configurations consistently improved porpoising mitigation metrics across all performance parameters. The selected configuration for the study transitioned from 180 N/mm to 120 N/mm at 30mm compression. Moreover, frequency domain analysis using Fast Fourier Transform and Power Spectral Density methods confirmed reduced system energy concentration at critical porpoising frequencies. Three passive mechanical implementations were comprehensively evaluated: magnetic assistance systems, dual-rate coil springs, and dual-rate torsion bars. While magnetic systems proved impractical due to limited linear operating ranges (maximum of 3.67mm) and extreme manufacturing tolerances, the dual-rate torsion bar system emerged as the optimal solution. This configuration achieved equivalent functionality with superior packaging efficiency (65% height reduction) and weight optimization (2.5kg total mass versus 3.41kg for coil springs). The research validates passive variable stiffness technology as an effective porpoising mitigation strategy, offering a purely mechanical solution that complies with current racing regulations. The dual-rate torsion bar system provides immediate implementation potential across ground effect racing applications, representing a paradigm shift from traditional aerodynamic compromises toward targeted suspension-based solutions. |
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