Browsing by Author "St Leger-Harris, Chris"

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    Experimental and numerical investigation of heave damper hydraulic seal for racing car
    (Elsevier, 2022-06-29) Azar, Michel; Grasso, Marzio; Rose, Timothy; Carless, Owen; St Leger-Harris, Chris; Lawson, Carl
    This article presents a combined experimental and numerical approach to analyse the failure of a heave damper hydraulic seal for racing car. The post-mortem analysis of the damaged seals was carried out with both optical microscopy and finite element analysis using material test data from Dynamic Modulus Analyser (DMA). The stress in the seal and damper was simulated modelling each step including the press-fitting on the piston, the interference with the cylinder and the oil pressure due to the service. The combination of the evidence collected from the numerical simulation and the observation of the surface damages on the seals proved that the cause of failure was the insufficient lubrication during high frequency, short stroke applications since these working conditions induce oil film break. The detailed damage mechanisms have been identified and explained and an alternative seal design that requires further study and testing in this application has been proposed.
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    Numerical simulation of plasticity in double lap metallic bolted joints
    (Taylor and Francis, 2023-02-08) Grasso, Marzio; Bai, Yuanli; Brighton, James; Carless, Owen; St Leger-Harris, Chris
    This article aims to compare three plasticity models, namely Bai-Wierzbicki (BW), von Mises and Drucker Prager, to predict the failure modes in double-lap metallic bolted joints under shear loading. The double-lap bolted joint finite element model has been validated against literature data, which demonstrated the application of BW ductile fracture model to bolt joint failure prediction. Taguchi Design is used to investigate the effects of geometrical parameters, preload and stress triaxiality on the failure modes. Force–displacement response amongst the three models differs up to 20% when failing in shear and a different prediction of the failure mode (shear out vs. net section) under the same loading and geometry conditions is observed.
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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.