TY - THES

T1 - Development of an automated preprocessor for the micromechanical modeling of foundry sands

AU - Ralph, Benjamin

N1 - no embargo

PY - 2018

Y1 - 2018

N2 - The focus of this thesis is the preparation of a preprocessor for the micromechanical modeling of molding material systems used in the foundry industry. Molding material testing is an essential aspect of quality assurance in the casting industry. The quality of the finished casting parts depends significantly on the various properties of the foundry sand and the associated binder system used. The aim of this master thesis was to create an executable input file for the finite element program Abaqus. This input file is capable of randomly arranging grains of variable grain size, with arbitrary grain size distribution in three-dimensional space, as well as corresponding binder systems of variable volume fraction. Sand grains are based on spherical geometry, which can be extended to more complex geometric figures. The density of the ball packing can be defined by the user and adapted to the respective requirement. The mechanical properties of the various sands and binder systems can be varied directly in the code. For the underlying material model of the binder system, data of previous experiments was collected, converted and integrated into the code. The formation of the binder bridges, which are mainly responsible for the strength of the molding material, is realized by a forced superimposition of binder sleeves. For the sake of computational efficiency, not the whole test specimen used in practice was modeled, but a statistically representative volume unit is generated. The relationship between this volume element and a real sample is made by a suitable set of boundary conditions, depending on the location of the considered unit in the real sample body. This preprocessor should function as a basis for a wide variety of micromechanical simulation models in the molding and foundry industry.

AB - The focus of this thesis is the preparation of a preprocessor for the micromechanical modeling of molding material systems used in the foundry industry. Molding material testing is an essential aspect of quality assurance in the casting industry. The quality of the finished casting parts depends significantly on the various properties of the foundry sand and the associated binder system used. The aim of this master thesis was to create an executable input file for the finite element program Abaqus. This input file is capable of randomly arranging grains of variable grain size, with arbitrary grain size distribution in three-dimensional space, as well as corresponding binder systems of variable volume fraction. Sand grains are based on spherical geometry, which can be extended to more complex geometric figures. The density of the ball packing can be defined by the user and adapted to the respective requirement. The mechanical properties of the various sands and binder systems can be varied directly in the code. For the underlying material model of the binder system, data of previous experiments was collected, converted and integrated into the code. The formation of the binder bridges, which are mainly responsible for the strength of the molding material, is realized by a forced superimposition of binder sleeves. For the sake of computational efficiency, not the whole test specimen used in practice was modeled, but a statistically representative volume unit is generated. The relationship between this volume element and a real sample is made by a suitable set of boundary conditions, depending on the location of the considered unit in the real sample body. This preprocessor should function as a basis for a wide variety of micromechanical simulation models in the molding and foundry industry.

KW - Finite Elemente

KW - Mikromechanik

KW - Formstoffprüfung

KW - Finite elements

KW - micromechanics

KW - molding material testing

M3 - Master's Thesis

ER -