Browsing by Author "Sheikh Al-Shabab, Ahmed A"

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    A mixed-elastohydrodynamic lubrication model of a capped-T-ring seal with a sectioned multi-material film thickness in landing gear shock absorber applications
    (MDPI, 2024-11-21) Feria Alanis, Aaron; Sheikh Al-Shabab, Ahmed A; Antoniadis, Antonis F; Tsoutsanis, Panagiotis; Skote, Martin
    Numerical investigations of capped T-ring (CTR) seals performance in reciprocating motion for landing gear shock absorber applications are presented. A lubrication model using the Elastohydrodynamic lubrication theory and deformation mechanics is developed in a multi-material contact zone, and a procedure for coupling fluid and deformation mechanics is introduced. By conducting Finite Element Method (FEM) simulations, the static contact pressure is obtained, which subsequently is used within the model developed herein consisting of a modified Reynolds equation and an asperity contact model, to calculate the fluid film pressure, and the deformation of the fluid channel is determined using an elastic deformation model applied to a multi-component multi-mechanical property channel. These computational results are used for estimations of the seal leakage and friction under various conditions. In addition, the influence of asperity orientation is compared with other parameters, such as sealing pressure and piston velocity. A correlation between asperity orientation and leakage was found, and a general trend of reduced leakage with longitudinally oriented asperities was established.
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    A modular multifidelity approach for multiphysics oleo-pneumatic shock absorber simulations
    (Springer Nature, 2024-12-03) Sheikh Al-Shabab, Ahmed A; Silva, Paulo ASF; Grenko, Bojan; Tsoutsanis, Panagiotis; Skote, Martin
    A numerical framework is developed and tested to simulate the internal dynamics of oleo-pneumatic shock absorbers. A modular approach is devised to address the multiphysics nature of the problem, starting with three dimensional scale resolving turbulence simulations and two dimensional axisymmetric multiphase URANS simulations. These simulations capture the main dominant aspects of energy dissipation through turbulence, and the multiphase mixing which can affect the working fluid properties. Internal flow simulations are run on a representative shock absorber geometry based on dimensions provided in the validation study together with sizing guidelines from the literature. A lower fidelity two-equation dynamic system solver is used to scan the design space and test the sensitivity towards various design parameters, in addition to identifying parameter combinations that would be of interest to investigate using higher fidelity methods.