Browsing by Author "Le Roux de Bretagne, Olivier"

Now showing 1 - 3 of 3
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    Comparative analysis of various hyperelastic models and element types for finite element analysis
    (MDPI, 2023-11-22) Lin, Po-Sen; Le Roux de Bretagne, Olivier; Grasso, Marzio; Brighton, James; StLeger-Harris, Chris; Carless, Owen
    This study aims to evaluate the precision of nine distinct hyperelastic models using experimental data sourced from the existing literature. These models rely on parameters obtained through curve-fitting functions. The complexity in finite element models of elastomers arises due to their nonlinear, incompressible behaviour. To achieve accurate representations, it is imperative to employ sophisticated hyperelastic models and appropriate element types and formulations. Prior published work has primarily focused on the comparison between the fitting models and the experimental data. Instead, in this study, the results obtained from finite element analysis are compared against the original data to assess the impact of element formulation, strain range, and mesh type on the ability to accurately predict the response of elastomers over a wide range of strain values. This comparison confirms that the element formulation and strain range can significantly influence result accuracy, yielding different responses in various strain ranges also because of the limitation with the curve fitting tools.
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    On a numerical methodology to assess the fatigue life of connecting rods
    (SAGE, 2023-06-18) Xu, Wentao; Le Roux de Bretagne, Olivier; Grasso, Marzio; Harrison, Matthew F.; Carless, Owen; St Leger-Harris, Chris
    Although simulation-based fatigue analysis is a standard tool adopted in every sector including automotive industry, the design of engine components in automotive and motorsport applications mostly relies on simplified design approaches supported by time-consuming testing programs. This manuscript proposes a new methodology based on individual engine speed damage estimation and engine speed time history combined with Palmgren-Miner linear damage rule to predict the fatigue state of the connecting rod. The track data, engine multibody simulation (AVL ExciteTM) and engine combustion simulation (AVL BoostTM) are used to generate the initial variable trace that is processed to obtain the block programs. Stress amplitude estimated with finite element analysis (Abaqus) are used to estimate the damage from S-N curve and the cumulative damage is estimated with Palmgren-Miner cumulative damage model. The method proposed is demonstrated using a connecting rod case study and the duty cycle from the race on Sebring international raceway. This work shows the suitability of the approach and the benefit in terms of accuracy in the prediction of the fatigue life.
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    Thermodynamic and combustion characteristics of ultra-high performance engines for motorsport applications
    (Cranfield University, 2023-08) Le Roux de Bretagne, Olivier; Harrisson, Matthew F.; Temple, Clive
    Using steady-state and transient one-dimensional gas dynamic engine models developed with AVL Boost™, critical assessment of the performance characteristics of the current 2014+ Formula One™ engine and of the future 2026 Formula One™ Power Unit are investigated. For the 2014+ regulations, a Digital Twin, aiming at replicating the trends of the real engine despite a lack of component-level-detail data, is created and used to scientifically explain how this engine achieves 50+% brake fuel conversion efficiency and to rank the contribution of each enabling technologies (high compression ratio, lean combustion, passive pre-chamber, direct injection, asymmetric valve profiles, MGU-H and waste gates used as pressure-relief valves). The impact of the 2026 Formula One™ Power Unit regulations on engine performance is investigated and highlights that the reduction in fuel flow will not only result in the obvious reduction in power output but also in in-cylinder pressure which introduces opportunities for enhanced combustion process and higher air/fuel ratios. Nevertheless, with the high MGU-K power, both the 2014+ and 2026 Power Units are predicted to have similar peak output power despite an advantage at low speed for the 2026 regulations thanks to the capacity of electric motor to produce torque at low speed. Using transient simulations, the impact of the removal of the MGU-H in the 2026 regulations is assessed and an anti-lag solution using the MGU-K called torque consuming is investigated. It is demonstrated that always operating the engine at full load during acceleration phases and using the MGU-K to absorb the excess power compared to the power demand / to control the amount of power delivered to the wheels helps to reduce turbo lag, improve engine efficiency, and reduce the need for the MGU-K to torque fill, but at the expense of a higher fuel consumption.