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Development of a cell centred upwind finite volume algorithm for a new conservation law formulation in structural dynamics. / Chun Hean Lee

Swansea University Author: Chun Hean Lee

Abstract

Over the past few decades, dynamic solid mechanics has become a major field of interest in industrial applications involving crash simulation, impact problems, forging and many others to be named. These problems are typically nonlinear due to large deformations (or geometrical nonlinearity) and nonl...

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Published: 2012
Institution: Swansea University
Degree level: Doctoral
Degree name: Ph.D
URI: https://cronfa.swan.ac.uk/Record/cronfa42726
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For this reason, computer simulations for such problems are of practical importance. In these simulations, the Lagrangian formulation is typically used as it automatically satisfies the mass conservation law. Explicit numerical methods are considered to be efficient in these cases. Most of the numerical methods employed for such simulations are developed from the equation of motion (or momentum balance principle). The use of low-order elements in these numerical methods often exhibits the detrimental locking phenomena in the analysis of nearly incompressible applications, which produces an undesirable effect leading to inaccurate results. Situations of this type are usual in the solid dynamics analysis for rubber materials and metal forming processes. In metal plasticity, the plastic deformation is isochoric (or volume-preserving) whereas, the compressible part is due only to elastic deformation. Recently, a new mixed formulation has been established for explicit Lagrangian transient solid dynamics. This formulation, involving linear momentum, deformation gradient and total energy, results in first order hyperbolic system of equations. Such conservation-law formulation enables stresses to converge at the same rate as velocities and displacements. In addition, it ensures that low order elements can be used without volumetric locking and/or bending difficulty for nearly incompressible applications. The new mixed formulation itself shows a clear advantage over the classical displacement-based formulation, due to its simplicity in incorporating state-of-the-art shock capturing techniques. In this research, a curl-preserving cell centred finite volume computational methodology is presented for solving the first order hyperbolic system of conservation laws on quadrilateral cartesian grids. First, by assuming that the approximation to the unknown variables is constant within each cell. This will lead to discontinuities at cell edges which will motivate the use of a Riemann solver by introducing an upwind bias into the evaluation of the numerical flux function. Unfortunately, the accuracy is severely undermined by an excess of numerical dissipation. In order to alleviate this, it is vital to introduce a linear reconstruction procedure for enhancing the accuracy of the scheme. However the second-order spatial method does not prohibit spurious oscillation in the vicinity of sharp gradients. To circumvent this, a nonlinear slope limiter will then be introduced. It is now possible to evolve the semi-discrete evolutionary system of ordinary equations in time with the aid of the family of explicit Total Variation Diminishing Runge Kutta (TVD-RK) time marching schemes. 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spelling 2018-08-02T16:24:30.2426040 v2 42726 2018-08-02 Development of a cell centred upwind finite volume algorithm for a new conservation law formulation in structural dynamics. 61e6ab37893c26024588abeef1f15649 NULL Chun Hean Lee Chun Hean Lee true true 2018-08-02 Over the past few decades, dynamic solid mechanics has become a major field of interest in industrial applications involving crash simulation, impact problems, forging and many others to be named. These problems are typically nonlinear due to large deformations (or geometrical nonlinearity) and nonlinear constitutive relations (or material nonlinearity). For this reason, computer simulations for such problems are of practical importance. In these simulations, the Lagrangian formulation is typically used as it automatically satisfies the mass conservation law. Explicit numerical methods are considered to be efficient in these cases. Most of the numerical methods employed for such simulations are developed from the equation of motion (or momentum balance principle). The use of low-order elements in these numerical methods often exhibits the detrimental locking phenomena in the analysis of nearly incompressible applications, which produces an undesirable effect leading to inaccurate results. Situations of this type are usual in the solid dynamics analysis for rubber materials and metal forming processes. In metal plasticity, the plastic deformation is isochoric (or volume-preserving) whereas, the compressible part is due only to elastic deformation. Recently, a new mixed formulation has been established for explicit Lagrangian transient solid dynamics. This formulation, involving linear momentum, deformation gradient and total energy, results in first order hyperbolic system of equations. Such conservation-law formulation enables stresses to converge at the same rate as velocities and displacements. In addition, it ensures that low order elements can be used without volumetric locking and/or bending difficulty for nearly incompressible applications. The new mixed formulation itself shows a clear advantage over the classical displacement-based formulation, due to its simplicity in incorporating state-of-the-art shock capturing techniques. In this research, a curl-preserving cell centred finite volume computational methodology is presented for solving the first order hyperbolic system of conservation laws on quadrilateral cartesian grids. First, by assuming that the approximation to the unknown variables is constant within each cell. This will lead to discontinuities at cell edges which will motivate the use of a Riemann solver by introducing an upwind bias into the evaluation of the numerical flux function. Unfortunately, the accuracy is severely undermined by an excess of numerical dissipation. In order to alleviate this, it is vital to introduce a linear reconstruction procedure for enhancing the accuracy of the scheme. However the second-order spatial method does not prohibit spurious oscillation in the vicinity of sharp gradients. To circumvent this, a nonlinear slope limiter will then be introduced. It is now possible to evolve the semi-discrete evolutionary system of ordinary equations in time with the aid of the family of explicit Total Variation Diminishing Runge Kutta (TVD-RK) time marching schemes. Moreover, a correction procedure involving minimisation algorithm for conservation of the total angular momentum is presented. To this end, a number of interesting examples will be examined in order to demonstrate the robustness and general capabilities of the proposed approach. E-Thesis Mechanical engineering.;Computer engineering. 31 12 2012 2012-12-31 COLLEGE NANME Engineering COLLEGE CODE Swansea University Doctoral Ph.D 2018-08-02T16:24:30.2426040 2018-08-02T16:24:30.2426040 Faculty of Science and Engineering School of Engineering and Applied Sciences - Uncategorised Chun Hean Lee NULL 1 0042726-02082018162517.pdf 10807495.pdf 2018-08-02T16:25:17.1670000 Output 18278581 application/pdf E-Thesis true 2018-08-02T16:25:17.1670000 false
title Development of a cell centred upwind finite volume algorithm for a new conservation law formulation in structural dynamics.
spellingShingle Development of a cell centred upwind finite volume algorithm for a new conservation law formulation in structural dynamics.
Chun Hean Lee
title_short Development of a cell centred upwind finite volume algorithm for a new conservation law formulation in structural dynamics.
title_full Development of a cell centred upwind finite volume algorithm for a new conservation law formulation in structural dynamics.
title_fullStr Development of a cell centred upwind finite volume algorithm for a new conservation law formulation in structural dynamics.
title_full_unstemmed Development of a cell centred upwind finite volume algorithm for a new conservation law formulation in structural dynamics.
title_sort Development of a cell centred upwind finite volume algorithm for a new conservation law formulation in structural dynamics.
author_id_str_mv 61e6ab37893c26024588abeef1f15649
author_id_fullname_str_mv 61e6ab37893c26024588abeef1f15649_***_Chun Hean Lee
author Chun Hean Lee
author2 Chun Hean Lee
format E-Thesis
publishDate 2012
institution Swansea University
college_str Faculty of Science and Engineering
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hierarchy_top_id facultyofscienceandengineering
hierarchy_top_title Faculty of Science and Engineering
hierarchy_parent_id facultyofscienceandengineering
hierarchy_parent_title Faculty of Science and Engineering
department_str School of Engineering and Applied Sciences - Uncategorised{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Engineering and Applied Sciences - Uncategorised
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description Over the past few decades, dynamic solid mechanics has become a major field of interest in industrial applications involving crash simulation, impact problems, forging and many others to be named. These problems are typically nonlinear due to large deformations (or geometrical nonlinearity) and nonlinear constitutive relations (or material nonlinearity). For this reason, computer simulations for such problems are of practical importance. In these simulations, the Lagrangian formulation is typically used as it automatically satisfies the mass conservation law. Explicit numerical methods are considered to be efficient in these cases. Most of the numerical methods employed for such simulations are developed from the equation of motion (or momentum balance principle). The use of low-order elements in these numerical methods often exhibits the detrimental locking phenomena in the analysis of nearly incompressible applications, which produces an undesirable effect leading to inaccurate results. Situations of this type are usual in the solid dynamics analysis for rubber materials and metal forming processes. In metal plasticity, the plastic deformation is isochoric (or volume-preserving) whereas, the compressible part is due only to elastic deformation. Recently, a new mixed formulation has been established for explicit Lagrangian transient solid dynamics. This formulation, involving linear momentum, deformation gradient and total energy, results in first order hyperbolic system of equations. Such conservation-law formulation enables stresses to converge at the same rate as velocities and displacements. In addition, it ensures that low order elements can be used without volumetric locking and/or bending difficulty for nearly incompressible applications. The new mixed formulation itself shows a clear advantage over the classical displacement-based formulation, due to its simplicity in incorporating state-of-the-art shock capturing techniques. In this research, a curl-preserving cell centred finite volume computational methodology is presented for solving the first order hyperbolic system of conservation laws on quadrilateral cartesian grids. First, by assuming that the approximation to the unknown variables is constant within each cell. This will lead to discontinuities at cell edges which will motivate the use of a Riemann solver by introducing an upwind bias into the evaluation of the numerical flux function. Unfortunately, the accuracy is severely undermined by an excess of numerical dissipation. In order to alleviate this, it is vital to introduce a linear reconstruction procedure for enhancing the accuracy of the scheme. However the second-order spatial method does not prohibit spurious oscillation in the vicinity of sharp gradients. To circumvent this, a nonlinear slope limiter will then be introduced. It is now possible to evolve the semi-discrete evolutionary system of ordinary equations in time with the aid of the family of explicit Total Variation Diminishing Runge Kutta (TVD-RK) time marching schemes. Moreover, a correction procedure involving minimisation algorithm for conservation of the total angular momentum is presented. To this end, a number of interesting examples will be examined in order to demonstrate the robustness and general capabilities of the proposed approach.
published_date 2012-12-31T03:53:32Z
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score 11.036706

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