Nichtlineare Finite-Elemente-Berechnungen

Rust, Wilhelm

doi:10.1007/978-3-8348-8148-9

Cited by 15 publications

(8 citation statements)

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“…This conversion helps to correct the effect of specimen elongation and of area reduction in the tensile test and thus leads to the true or real values. It is based on the following equations, which are recommended by Rust:

ε_{log} = l n ((), 1 + ε_{i n g})

σ_{real} = σ_{i n g} ((), 1 + ε_{i n g}) .

…”

Section: Validation Of the Methodsmentioning

confidence: 99%

Design rules for autofrettage of an aluminium valve body

Sellen

Maas

Andreas³

et al. 2015

Fatigue Fract Eng Mat Struct

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The following paper is intended to improve the fatigue behaviour of a complex aluminium valve geometry under high internal cyclic pressure loading. The autofrettage process helps to increase the fatigue durability and a simple but efficient design method for this process is pointed out. Based on non-linear material's behaviour, finite element simulations of the crack-free geometry help to determine the minimum and maximum autofrettage pressure to be used, without iterative crack simulations, which would require a lot of computational time. Material tests under inverse plastifications were performed in order to determine the correct material model. The derived design method was verified with simplified specimens subjected to different autofrettage pressure levels and subsequent cyclic fatigue tests.

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ε_{log} = l n ((), 1 + ε_{i n g})

σ_{real} = σ_{i n g} ((), 1 + ε_{i n g}) .

…”

Section: Validation Of the Methodsmentioning

confidence: 99%

Design rules for autofrettage of an aluminium valve body

Sellen

Maas

Andreas³

et al. 2015

Fatigue Fract Eng Mat Struct

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“…For a simple account of viscoelasticity of materials, two models are established. These are the Maxwell model and the Kelvin–Voigt model . The Maxwell model consists of a purely elastic spring and a purely viscous damper connected in series.…”

Section: Methodsmentioning

confidence: 99%

Modeling of transient flow through a viscoelastic preparative chromatography packing

Hekmat

Kühn

Meinhardt

et al. 2013

Biotechnology Progress

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The common method for purification of macromolecular bioproducts is preparative packed-bed chromatography using polymer-based, compressible, viscoelastic resins. Because of a downstream processing bottleneck, the chromatography equipment is often operated at its hydrodynamic limit. In this case, the resins may exhibit a complex behavior which results in compression-relaxation hystereses. Up to now, no modeling approach of transient flow through a chromatography packing has been made considering the viscoelasticity of the resins. The aim of the present work was to develop a novel model and compare model calculations with experimental data of two agarose-based resins. Fluid flow and bed permeability were modeled by Darcy's law and the Kozeny-Carman equation, respectively. Fluid flow was coupled to solid matrix stress via an axial force balance and a continuity equation of a deformable packing. Viscoelasticity was considered according to a Kelvin-Voigt material. The coupled equations were solved with a finite difference scheme using a deformable mesh. The model boundary conditions were preset transient pressure drop functions which resemble simulated load/elution/equilibration cycles. Calculations using a homogeneous model (assuming constant variables along the column height) gave a fair agreement with experimental data with regard to predicted flow rate, bed height, and compression-relaxation hysteresis for symmetric as well as asymmetric pressure drop functions. Calculations using an inhomogeneous model gave profiles of the bed porosity as a function of the bed height. In addition, the influence of medium wall support and intraparticle porosity was illustrated. The inhomogeneous model provides insights that so far are not easily experimentally accessible.

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“…To do so, the Nusselt number is calculated automatically by the simulation tool using empirical equations of Müller (Müller, 1999). For Nusselt numbers larger than 1, equation 4 will be applicable, if not, the value of Nu is set to 1, which means that no natural convection exists within the gap.…”

Section: Conduction and Convectionmentioning

confidence: 99%

Influence of Gas-Filled Gaps on the Thermal Behaviour of Dual Purpose Casks

Dinkel

Billenstein

Rieg

et al. 2019

Proc. Int. Conf. Eng. Des.

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Basically, the safe dissipation of heat is among others an important protection objective of dual purpose casks. Gas-filled gaps within such casks can play a major role for the thermal behavior as they act as thermal barriers due to the lower heat conductivity of gaseous fluids in comparison to metallic materials. However, additional heat transmission mechanisms, such as natural convection and radiation can also occur in a gaseous medium. This leads to both an expanded modelling and a prolonged computing time in numerical simulations. Within the scope of a research project in cooperation with Swiss Federal Nuclear Safety Inspectorate ENSI a simulation tool for the fast thermal evaluation of dual purpose casks is developed which combines analytical methods and FEA. The innovation is that the thermal effects of gas-filled gaps are considered by using analytical equations. Main focus lies on the implementation of heat radiation as a non-linear transfer mechanism. Therefore, an iterative calculation process is used and the effects of the iteration number is investigated. Furthermore, the influence of radiation in comparison to pure conduction is examined depending on the gap width.

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Nichtlineare Finite-Elemente-Berechnungen

Cited by 15 publications

References 0 publications

Design rules for autofrettage of an aluminium valve body

Design rules for autofrettage of an aluminium valve body

Modeling of transient flow through a viscoelastic preparative chromatography packing

Influence of Gas-Filled Gaps on the Thermal Behaviour of Dual Purpose Casks

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