The Experts below are selected from a list of 9621 Experts worldwide ranked by ideXlab platform
Emile S Greenhalgh - One of the best experts on this subject based on the ideXlab platform.
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on the dynamic tensile behaviour of thermoplastic composite carbon polyamide 6 6 using split hopkinson pressure bar
Materials, 2021Co-Authors: Muhammad Ameerul Atrash Mohsin, L Iannucci, Emile S GreenhalghAbstract:A dynamic tensile experiment was performed on a rectangular specimen of a non-crimp fabric (NCF) thermoplastic composite T700 carbon/polyamide 6.6 specimens using a split Hopkinson pressure (Kolsky) bar (SHPB). The experiment successfully provided useful information on the strain-rate sensitivity of the NCF carbon/thermoplastic material system. The average tensile strength at three varying strain rates: 700, 1400, and 2100/s was calculated and compared to the tensile strength measured from a standardized (quasi-static) procedure. The increase in tensile strength was found to be 3.5, 24.2, and 45.1% at 700, 1400, and 2100/s strain rate, respectively. The experimental findings were used as input parameters for the numerical model developed using a commercial finite element (FE) Explicit Solver LS-DYNA®. The dynamic FE model was validated against experimental gathering and used to predict the composite system's behavior in various engineering applications under high strain-rate loading conditions. The SHPB tension test detailed in this study provided the enhanced understanding of the T700/polyamide 6.6 composite material's behavior under different strain rates and allowed for the prediction of the material's behavior under real-world, dynamic loading conditions, such as low-velocity and high-velocity impact.
Le D Touze - One of the best experts on this subject based on the ideXlab platform.
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a cartesian Explicit Solver for complex hydrodynamic applications
ASME 2014 33rd International Conference on Ocean Offshore and Arctic Engineering, 2014Co-Authors: P Bigay, A Bardin, G Oger, Le D TouzeAbstract:In order to efficiently address complex problems in hydrodynamics, the advances in the development of a new method are presented here. This method aims at finding a good compromise between computational efficiency, accuracy, and easy handling of complex geometries. The chosen method is an Explicit Cartesian Finite Volume method for Hydrodynamics (ECFVH) based on a compressible (hyperbolic) Solver, with a ghost-cell method for geometry handling and a Level-set method for the treatment of biphase-flows. The Explicit nature of the Solver is obtained through a weakly-compressible approach chosen to simulate nearly-incompressible flows. The Explicit cell-centered resolution allows for an efficient solving of very large simulations together with a straightforward handling of multi-physics. A characteristic flux method for solving the hyperbolic part of the Navier-Stokes equations is used. The treatment of arbitrary geometries is addressed in the hyperbolic and viscous framework. Viscous effects are computed via a finite difference computation of viscous fluxes and turbulent effects are addressed via a Large-Eddy Simulation method (LES). The Level-Set Solver used to handle biphase flows is also presented. The Solver is validated on 2-D test cases (flow past a cylinder, 2-D dam break) and future improvements are discussed.Copyright © 2014 by ASME
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development of a new cartesian Explicit Solver for hydrodynamics flows
ASME 2013 32nd International Conference on Ocean Offshore and Arctic Engineering, 2013Co-Authors: P Bigay, G Oger, Le D Touze, C Leroy, P M GuilcherAbstract:In order to solve complex problems in hydrodynamics, a new method is developed. This method aims at finding a good compromise between computational efficiency, accuracy, and easy handling of complex geometries. The chosen method is an Explicit Cartesian Finite Volume method for Hydrodynamics (ECFVH) based on a compressible (hyperbolic) Solver, with an embedded method for interfaces and geometry handling. The Explicit nature of the Solver is obtained through a weakly-compressible approach chosen to simulate nearly-incompressible flows. The Explicit cell-centered resolution allows for an efficient solving of very large simulations together with a straightforward handling of multi-physics. The use of an embedded Cartesian grid ensures accuracy and efficiency, but also implies the need for a specific treatment of complex solid geometries, such as the cut-cell method in the fixed or moving body frame. Robustness of the cut-cell method is ensured by specific procedures to circumvent small cell volume numerical errors. A characteristic flux method for solving the hyperbolic part of the Navier-Stokes equations is used for which upwinding is necessary, also introducing numerical viscosity. This numerical viscosity is evaluated before trying to model viscous and turbulent effects. In a first approach viscous effects are computed via a finite difference Laplacian operator introduced as a source term. This Solver is validated on 2-D test cases and future improvements are discussed.Copyright © 2013 by ASME
E. Codina - One of the best experts on this subject based on the ideXlab platform.
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Numerical simulation of a supersonic ejector for vacuum generation with Explicit and implicit Solver in openfoam
Energies, 2019Co-Authors: Ll Macia, R. Castilla, P. J. Gamez-montero, S. Camacho, E. CodinaAbstract:Supersonic ejectors are used extensively in all kind of applications: compression of refrigerants in cooling systems, pumping of volatile fluids or in vacuum generation. In vacuum generation, also known as zero-secondary flow, the ejector has a transient behaviour. In this paper, a numerical and experimental research of a supersonic compressible air nozzle is performed in order to investigate and to simulate its behaviour. The CFD toolbox OpenFOAM 6 was used, with two density-based Solvers: Explicit Solver rhoCentralFoam, which implements Kurganov Central-upwind schemes, and implicit Solver HiSA, which implements the AUSM+up upwind scheme. The behaviour of the transient evacuation ranges between adiabatic polytropic exponent at the beginning of the process and isothermal at the end. A model for the computation of the transient polytropic exponent is proposed. During the evacuation, two regimes are encountered in the second nozzle. In the supercritic regime, the secondary is choked and sonic flow is reached. In the subcritic regime, the secondary flow is subsonic. The final agreement is good with the two different Solvers, although simulation tends to slightly overestimate flow rate for large values region.
Conor T. Mccarthy - One of the best experts on this subject based on the ideXlab platform.
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Modelling bearing failure in countersunk composite joints under quasi-static loading using 3D Explicit finite element analysis
Composite Structures, 2014Co-Authors: Brian Egan, R M Frizzell, Michael A. Mccarthy, P.j. Gray, Conor T. MccarthyAbstract:Abstract Three-dimensional Explicit finite element modelling is used to predict the quasi-static bearing response of typical countersunk composite fuselage skin joints. In order to accurately simulate bearing failure, a user-defined 3D composite damage model was formulated for Abaqus/Explicit and included Puck failure criteria, a nonlinear shear law and a crack band model to mitigate mesh sensitivity. A novel approach was developed to employ characteristic element lengths which account for the orientation of composite ply cracks in the Abaqus/Explicit Solver. Resulting models accurately predicted initial joint sticking behaviour and the elastic loading response of single-bolt and three-bolt joints, but preliminary predictions of bearing failure onset were overly-conservative. Improved failure predictions were obtained by utilising a fracture energy for compressive fibre failure which was considered more relevant for simulating bearing damage. The Explicit models were exceptionally robust, showing capability to predict extensive hole crushing. Methods of dramatically improving joint model efficiency were highlighted.
P Bigay - One of the best experts on this subject based on the ideXlab platform.
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a cartesian Explicit Solver for complex hydrodynamic applications
ASME 2014 33rd International Conference on Ocean Offshore and Arctic Engineering, 2014Co-Authors: P Bigay, A Bardin, G Oger, Le D TouzeAbstract:In order to efficiently address complex problems in hydrodynamics, the advances in the development of a new method are presented here. This method aims at finding a good compromise between computational efficiency, accuracy, and easy handling of complex geometries. The chosen method is an Explicit Cartesian Finite Volume method for Hydrodynamics (ECFVH) based on a compressible (hyperbolic) Solver, with a ghost-cell method for geometry handling and a Level-set method for the treatment of biphase-flows. The Explicit nature of the Solver is obtained through a weakly-compressible approach chosen to simulate nearly-incompressible flows. The Explicit cell-centered resolution allows for an efficient solving of very large simulations together with a straightforward handling of multi-physics. A characteristic flux method for solving the hyperbolic part of the Navier-Stokes equations is used. The treatment of arbitrary geometries is addressed in the hyperbolic and viscous framework. Viscous effects are computed via a finite difference computation of viscous fluxes and turbulent effects are addressed via a Large-Eddy Simulation method (LES). The Level-Set Solver used to handle biphase flows is also presented. The Solver is validated on 2-D test cases (flow past a cylinder, 2-D dam break) and future improvements are discussed.Copyright © 2014 by ASME
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development of a new cartesian Explicit Solver for hydrodynamics flows
ASME 2013 32nd International Conference on Ocean Offshore and Arctic Engineering, 2013Co-Authors: P Bigay, G Oger, Le D Touze, C Leroy, P M GuilcherAbstract:In order to solve complex problems in hydrodynamics, a new method is developed. This method aims at finding a good compromise between computational efficiency, accuracy, and easy handling of complex geometries. The chosen method is an Explicit Cartesian Finite Volume method for Hydrodynamics (ECFVH) based on a compressible (hyperbolic) Solver, with an embedded method for interfaces and geometry handling. The Explicit nature of the Solver is obtained through a weakly-compressible approach chosen to simulate nearly-incompressible flows. The Explicit cell-centered resolution allows for an efficient solving of very large simulations together with a straightforward handling of multi-physics. The use of an embedded Cartesian grid ensures accuracy and efficiency, but also implies the need for a specific treatment of complex solid geometries, such as the cut-cell method in the fixed or moving body frame. Robustness of the cut-cell method is ensured by specific procedures to circumvent small cell volume numerical errors. A characteristic flux method for solving the hyperbolic part of the Navier-Stokes equations is used for which upwinding is necessary, also introducing numerical viscosity. This numerical viscosity is evaluated before trying to model viscous and turbulent effects. In a first approach viscous effects are computed via a finite difference Laplacian operator introduced as a source term. This Solver is validated on 2-D test cases and future improvements are discussed.Copyright © 2013 by ASME
