Werkstoffverhalten unter zügiger elastischer Beanspruchung

Evertz, Th.; Sonne, H.-M.; Steinbeck, G.; Engl, Bernhard

doi:10.1002/mawe.200400768

Cited by 15 publications

(16 citation statements)

References 2 publications

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“…Therefore, the elastic parameters of pure iron given in literature have been applied: C 1111 = 226 000 MPa, C 2222 = 140 000 MPa, and C 1122 = 116 000 MPa . With this approach the predicted macroscopic elastic moduli are 210 GPa in rolling direction, 220 GPa in diagonal and 212 GPa in transverse direction and in good agreement with values reported in literature …”

Section: Using Single Crystal Plasticity and Numerical Homogenizationsupporting

confidence: 89%

“…[32] With this approach the predicted macroscopic elastic moduli are 210 GPa in rolling direction, 220 GPa in diagonal and 212 GPa in transverse direction and in good agreement with values reported in literature. [33] The microstructure of the DC04 material consists of ferrite grains with a bcc crystallographic lattice. For this lattice type plastic slip on three different types of slip system families has been observed.…”

Section: Identification Of the Materials Parametermentioning

confidence: 99%

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Determination of Mechanical Properties of Polycrystals by Using Crystal Plasticity and Numerical Homogenization Schemes

Baiker

Helm

Butz

2014

steel research int.

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The modeling and simulation of metal forming processes is typically based on experimental data. Unfortunately, the experimental investigation of the mechanical behavior and the related properties of polycrystalline materials is a difficult task, because only limited stress and strain states can be investigated experimentally. For example, the testing of sheet metals is simple under tension, complex under compression due to buckling, and costly under biaxial load. In order reduce these drawbacks, a virtual testing concept is applied. In this concept, the behavior of single crystals is modeled by crystal plasticity and the behavior of polycrystalline microstructures is represented by using finite element solutions of periodic microstructures. The success of the strategy is validated on the mild steel DC04. In order to calibrate the virtual testing, only a small number of experimental information like crystallographic and morphologic texture and tension test data will be incorporated. Other quantities, like the tension behavior in other directions, the multi‐axial material behavior, as well as the Lankford coefficients and the initial yield behavior will be predicted by virtual testing and compared to experimental data for validation. The demonstrated approach for calibrating the virtual testing and for predicting key material values is successful and leads to valuable contributions to the modeling and simulation of sheet metals.

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Section: Using Single Crystal Plasticity and Numerical Homogenizationsupporting

confidence: 89%

Section: Identification Of the Materials Parametermentioning

confidence: 99%

Determination of Mechanical Properties of Polycrystals by Using Crystal Plasticity and Numerical Homogenization Schemes

Baiker

Helm

Butz

2014

steel research int.

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“…For practical purposes this limits the system sizes for determining the impurity energies to a periodic 16 × 16 lattice for the 2D geometry. The quantum Monte Carlo program we developed uses the loop algorithm in a single cluster variety implemented in continuous time [12][13][14][15], which gives efficient and fast updates even at very low temperatures. From now on all temperatures and energies are given in units of J = 1.…”

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confidence: 99%

Interaction effects between impurities in low-dimensional spin-(1/2) antiferromagnets

Anfuso

Eggert

2006

Europhys. Lett.

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PACS. 75.10.Jm -Quantized Spin Models. PACS. 75.30.Hx -Magnetic impurity interactions.Abstract. -We are considering the interplay between several non-magnetic impurities in the spin-1/2 Heisenberg antiferromagnet in chains, ladders and planes by introducing static vacancies in numerical quantum Monte Carlo simulations. The effective potential between two and more impurities is accurately determined, which gives a direct measure of the quantum correlations in the systems. Large effective interaction potentials are an indication of strong quantum correlations in the system and reflect the detailed nature of the valence bond ground states. In two-dimensions (2D) the interactions are smaller, but can still be analyzed in terms of valence bonds.Introduction. -The interplay between impurities in antiferromagnetic backgrounds has become an important topic ever since the discovery of high-temperature superconductivity. The interaction energy between mobile holes has been examined with a variety of numerical and analytical methods for t-J and Hubbard models in order to get a better insight into the pairing mechanism in the HiT c compounds [1][2][3][4]. Equally interesting is the effect of static impurities [5][6][7][8][9] which for example are known to induce spin-1/2 degrees in ladders, that interact to form gapless excitations in otherwise gapped systems [10,11]. For static vacancies one of the first studies was performed by Bulut et al. with linear spin-wave approximation and numerics on small lattices [5], establishing a nearest neighbor attraction and an interesting enhancement of the local quantum correlations.We are now considering several static holes (vacancies) in low dimensional antiferromagnets like chains, ladders and planes on larger lattices, in order to calculate their impurity and interaction energies in the limit of zero temperature. The energies are changed because nearest neighbor correlations S i · S j are altered around the vacancies which in turn visualize the quantum correlations on the lattice. Therefore the interaction energy between two or more impurities gives direct information on the quantum correlations by showing the underlying local valence bond order as will be explained for a variety of configurations in the antiferromagnetic spin-1/2 Heisenberg model H = J i,j S i · S j where i, j denotes nearest neighbor sites on chain, ladder and square lattices.In order to determine impurity contributions to the total energy and the effective potentials between vacancies we have to sum up all bond strengths in the system and subtract the

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“…The model is the 2D Heisenberg spin-1/2 antiferromagnet H = J i,j S i · S j where i, j denotes nearest neighbor sites on a periodic square lattice. The quantum Monte Carlo program we developed uses the loop algorithm in a single cluster variety implemented in continuous time [21,22,23,24], which gives efficient updates even at very low temperatures on a lattice of 100 × 100 sites. For convenience temperatures and energies are given in units of J = 1.…”

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confidence: 99%

Knight Shifts around Vacancies in the 2D Heisenberg Model

Anfuso

Eggert

2006

Phys. Rev. Lett.

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The local response to a uniform field around vacancies in the two-dimensional (2D) spin-1/2 Heisenberg antiferromagnet is determined by numerical quantum Monte Carlo simulations as a function of temperature. It is possible to separate the Knight shifts into uniform and staggered contributions on the lattice which are analyzed and understood in detail. The contributions show interesting long and short range behavior that may be of relevance in NMR and susceptibility measurements. For more than one impurity remarkable non-linear enhancement and cancellation effects take place. We predict that the Curie impurity susceptibility will be observable for a random impurity concentration even in the thermodynamic limit.PACS numbers: 75.10. Jm, 74.25.Nf, 75.20.Hr, 75.40.Mg The deliberate use of substitutional impurities in strongly correlated electron systems has become a valuable tool for controlled studies of the underlying correlations [1,2,3,4,5]. Doping of non-magnetic Znions in antiferromagnetic CuO 2 planes is known to lead to a surprisingly large reduction of T c [1] and induces local staggered magnetic moments around the impurity sites [2]. It has now become quite standard to analyze the local magnetic moments around static magnetic and non-magnetic impurities in an antiferromagnetic background for a deeper understanding of the correlated states [3,4,5].Theoretically the Knight shifts around impurities and vacancies have been studied for many low-dimensional antiferromagnets [6,7,8,9,10,11,12], which typically show a strong enhancement of the antiferromagnetic order. The detailed behavior of the staggered magnetic moments can even give rather exotic results such as an increasing amplitude as a function of distance [7] and show renormalization effects [11,12]. The magnetization pattern can often be interpreted as the interference of incoming and scattered quasiparticle excitations [11] or in terms of a pruned valence bond basis [8].The sum of all Knight shifts adds up to the total susceptibility χ 1 . The resulting impurity susceptibility χ imp = χ 1 − χ 0 has been studied in detail in more recent theoretical studies [13,14,15,16,17,18,19,20]. In systems with long range magnetic order the leading temperature dependence of the impurity susceptibility from one single vacancy is given by a classical Curie spin which has been confirmed by numerical simulations for the 2D Heisenberg antiferromagnet [14,15], where a subleading logarithmic term has also been established [13,14,15,16,17] Here χ 0 is the total susceptibility without any impurities, ρ s is the spin stiffness, and the limit of large correlation length ξ(T ) and system size ξ(T ) > L → ∞ is assumed.We now want to examine how this impurity susceptibility is distributed on the lattice by considering the linear local response to a small uniform magnetic field (Knight shift) at each siteWe find that long and short range patterns of the Knight shifts contribute to the impurity susceptibility differently. We are able to study the interference of several impuritie...

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Werkstoffverhalten unter zügiger elastischer Beanspruchung

Cited by 15 publications

References 2 publications

Determination of Mechanical Properties of Polycrystals by Using Crystal Plasticity and Numerical Homogenization Schemes

Determination of Mechanical Properties of Polycrystals by Using Crystal Plasticity and Numerical Homogenization Schemes

Interaction effects between impurities in low-dimensional spin-(1/2) antiferromagnets

Knight Shifts around Vacancies in the 2D Heisenberg Model

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