Smoothed particle hydrodynamics for high velocity impact simulations

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Title: Smoothed particle hydrodynamics for high velocity impact simulations
Authors: Connolly, Adam
Item Type: Thesis or dissertation
Abstract: The subject of this work is the application of the Smoothed Particle Hydrodynamics (SPH) method to modelling high-velocity impact dynamics. The first part of this thesis proposes an extension of the original first-order Godunov SPH scheme, for material with strength, to second-order in space using a time-splitting approach for the hydrodynamic and deviatoric components of the stress tensor. A non-linear slope-limiting procedure is used to extend the hydrodynamic component to second-order while the deviatoric component is discretized directly. Exact conservation of total energy is enforced in the new scheme using a time-centering approach for the velocity field. The new scheme is shown to perform well for a variety of one and two-dimensional fluid and solid-dynamics test cases. In particular, the numerical viscosity is shown to be lower than the original first-order scheme and particle clustering is less pronounced than in the standard artificial viscosity method. The second part of this thesis applies the newly developed SPH scheme to modelling high-velocity impacts on a synthetic porous poly-crystalline graphite material. In the course of investigation it was found that the applicability of the porous P - α equation of state is questionable for this type of graphite; an experimental investigation concluded that the assumptions required for the use of the porous equation of state are invalid. Therefore, an empirically derived polynomial equation of state is proposed instead. A widely used material model for brittle materials, based on the Continuum Damage Mechanics (CDM) approach, is used for the graphite deviatoric constitutive equation. In light of the time-splitting procedure, an algorithm for inclusion of CDM constitutive models was developed. Numerical simulations of high velocity impacts on the graphite material were then performed and compared with experimental results.
Content Version: Open Access
Issue Date: Jul-2013
Date Awarded: May-2013
URI: http://hdl.handle.net/10044/1/17983
Supervisor: Iannucci, Lorenzo
Hillier, Richard
Warburton, Keith
Sponsor/Funder: Defence Science and Technology Laboratory (Great Britain)
Department: Aeronautics
Publisher: Imperial College London
Qualification Level: Doctoral
Qualification Name: Doctor of Philosophy (PhD)
Appears in Collections:Aeronautics PhD theses



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