The Experts below are selected from a list of 90 Experts worldwide ranked by ideXlab platform
Paul Steinmann - One of the best experts on this subject based on the ideXlab platform.
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Material Force method within the framework of the x fem distribution of nodal Material Forces
Pamm, 2007Co-Authors: J Glaser, Paul SteinmannAbstract:The Material Force Method (MFM) and the Extended Finite Element Method (X-FEM), both have been major subjects of computational fracture mechanics in recent time. Thus combining the advantages of both concepts [1, 2] seems a promising approach to describe the behaviour of discontinuities such as cracks in otherwise continuous bodies. As the X-FEM models a crack independently of the mesh, the crack tip is in general not located at a node which is why a central question is, which nodal Material Forces do contribute to the resulting Material Force vector at the crack tip. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
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on the comparison of two approaches to compute Material Forces for inelastic Materials application to single slip crystal plasticity
Computer Methods in Applied Mechanics and Engineering, 2004Co-Authors: Andreas Menzel, Ralf Denzer, Paul SteinmannAbstract:Abstract The main goal of this contribution is the application of the Material Force method to dissipative Materials whereby special emphasis is placed on the application to crystal-plasticity. Balance equations on the Material manifold, as e.g. the Material motion balance of momentum, generally necessitate the computation of the spatial gradient of additional internal degrees of freedom or rather internal variables. We therefore focus in this work on the comparison of two different numerical approaches to compute these gradient fields within a finite element setting, namely a node point based––and an integration point based formulation. Several numerical examples underline that the latter framework, which is the convenient, numerically comparatively cheap and well-established approach in computational inelasticity, turns out to be sufficiently accurate for the problem at hand.
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studies in elastic fracture mechanics based on the Material Force method
International Journal for Numerical Methods in Engineering, 2003Co-Authors: Ralf Denzer, Franz Josef Barth, Paul SteinmannAbstract:The object of this work is to discuss a further improvement of the Material Force method for non-linear hyperelastostatic fracture mechanics. We investigate the accuracy of the Material Force method within a 'modified boundary layer'-formulation using a Ramberg-Osgood Material type for the sake of comparison. The proposed improvement leads to a reliable and very accurate method to compute the vectorial J-integral in fracture mechanics.
Ralf Denzer - One of the best experts on this subject based on the ideXlab platform.
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on the comparison of two approaches to compute Material Forces for inelastic Materials application to single slip crystal plasticity
Computer Methods in Applied Mechanics and Engineering, 2004Co-Authors: Andreas Menzel, Ralf Denzer, Paul SteinmannAbstract:Abstract The main goal of this contribution is the application of the Material Force method to dissipative Materials whereby special emphasis is placed on the application to crystal-plasticity. Balance equations on the Material manifold, as e.g. the Material motion balance of momentum, generally necessitate the computation of the spatial gradient of additional internal degrees of freedom or rather internal variables. We therefore focus in this work on the comparison of two different numerical approaches to compute these gradient fields within a finite element setting, namely a node point based––and an integration point based formulation. Several numerical examples underline that the latter framework, which is the convenient, numerically comparatively cheap and well-established approach in computational inelasticity, turns out to be sufficiently accurate for the problem at hand.
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studies in elastic fracture mechanics based on the Material Force method
International Journal for Numerical Methods in Engineering, 2003Co-Authors: Ralf Denzer, Franz Josef Barth, Paul SteinmannAbstract:The object of this work is to discuss a further improvement of the Material Force method for non-linear hyperelastostatic fracture mechanics. We investigate the accuracy of the Material Force method within a 'modified boundary layer'-formulation using a Ramberg-Osgood Material type for the sake of comparison. The proposed improvement leads to a reliable and very accurate method to compute the vectorial J-integral in fracture mechanics.
Huajian Gao - One of the best experts on this subject based on the ideXlab platform.
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a Material Force method for inelastic fracture mechanics
Journal of The Mechanics and Physics of Solids, 2005Co-Authors: Thao D Nguyen, Sanjay Govindjee, P A Klein, Huajian GaoAbstract:Abstract A Material Force method is proposed for evaluating the energy release rate and work rate of dissipation for fracture in inelastic Materials. The inelastic Material response is characterized by an internal variable model with an explicitly defined free energy density and dissipation potential. Expressions for the global Material and dissipation Forces are obtained from a global balance of energy–momentum that incorporates dissipation from inelastic Material behavior. It is shown that in the special case of steady-state growth, the global dissipation Force equals the work rate of dissipation, and the global Material Force and J-integral methods are equivalent. For implementation in finite element computations, an equivalent domain expression of the global Material Force is developed from the weak form of the energy–momentum balance. The method is applied to model problems of cohesive fracture in a remote K-field for viscoelasticity and elastoplasticity. The viscoelastic problem is used to compare various element discretizations in combination with different schemes for computing strain gradients. For the elastoplastic problem, the effects of cohesive and bulk properties on the plastic dissipation are examined using calculations of the global dissipation Force.
E H Davies - One of the best experts on this subject based on the ideXlab platform.
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the influence of bracket Material ligation Force and wear on frictional resistance of orthodontic brackets
Journal of Orthodontics, 1993Co-Authors: O Keith, S P Jones, E H DaviesAbstract:AbstractPlanar static frictional phenomena were investigated for two types of ceramic and one type of stainless steel orthodontic bracket against rectangular stainless steel archwire. The brackets studied were ‘Starfire’ (single crystal aluminium oxide), ‘Allure III’ (polycrystalline aluminium oxide), and ‘Dentaurum’ (stainless steel). The investigative parameters were: bracket Material, Force of ligation and whether the brackets were new or ‘worn’.Without exception, both types of ceramic bracket produced greater frictional resistance than the stainless steel brackets throughout testing. At a ligation Force of 500 g, the Starfire bracket gave the greatest frictional resistance. At ligation Forces of 200 and 50 g, the greatest frictional resistance was seen with Allure III. After a period of simulated wear, frictional resistance of Starfire tended to increase at the greatest ligation load while that of both ceramics decreased slightly at the two lower ligation loads. The ceramic brackets caused abrasive we...
Thao D Nguyen - One of the best experts on this subject based on the ideXlab platform.
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a Material Force method for inelastic fracture mechanics
Journal of The Mechanics and Physics of Solids, 2005Co-Authors: Thao D Nguyen, Sanjay Govindjee, P A Klein, Huajian GaoAbstract:Abstract A Material Force method is proposed for evaluating the energy release rate and work rate of dissipation for fracture in inelastic Materials. The inelastic Material response is characterized by an internal variable model with an explicitly defined free energy density and dissipation potential. Expressions for the global Material and dissipation Forces are obtained from a global balance of energy–momentum that incorporates dissipation from inelastic Material behavior. It is shown that in the special case of steady-state growth, the global dissipation Force equals the work rate of dissipation, and the global Material Force and J-integral methods are equivalent. For implementation in finite element computations, an equivalent domain expression of the global Material Force is developed from the weak form of the energy–momentum balance. The method is applied to model problems of cohesive fracture in a remote K-field for viscoelasticity and elastoplasticity. The viscoelastic problem is used to compare various element discretizations in combination with different schemes for computing strain gradients. For the elastoplastic problem, the effects of cohesive and bulk properties on the plastic dissipation are examined using calculations of the global dissipation Force.
