Wyniki wyszukiwania - Biblioteka Nauki

1

Simulation of propagative instability in shear using gradient-enhanced and viscoplastic model

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Mucha M. , Wcisło B. , Pamin J.

Computer Methods in Materials Science

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2019

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tom Vol. 19, No. 2

57--63

EN

The research presented in this paper is focused on simulation of a propagative instability called Lueders bands using large strain plasticity with Huber-Mises-Hencky yield function. Two types of regularization are used: gradient-enhanced plasticity and viscoplasticity. Regularization is needed to avoid mesh sensitivity associated with the classical continuum description. A special sample is used to study Lueders band propagation in shear, its shape is motivated by experiments. The gradient-enhanced model used in computation provides a more reliable regularization than the viscoplastic model.

PL

W artykule zaprezentowano symulacje numeryczne propagujących się pasm lokalizacji odkształcenia nazywanych pasmami Luedersa wykorzystując model dużych deformacji z funkcją plastyczności Hubera-Mises-Hencky'ego. Użyto dwóch typów regularyzacji, gradientowej plastyczności oraz lepkoplastyczności. Regularyzacja jest niezbędna celem uniknięcia zależności wyników od gęstości siatki elementów skończonych. Do przeprowadzania obliczeń w warunkach czystego ścinania została użyta specjalna próbka, której kształt motywowany jest eksperymentami. Model gradientowy wykazał lepsze możliwości regularyzacyjne niż model lepkoplastyczny.

2

Simulations of concrete response to impact loading using two regularized models

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Wosatko A. , Winnicki A. , Pamin J.

Computer Assisted Methods in Engineering and Science

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2020

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tom Vol. 27, no. 1

27--60

EN

This paper focuses on a comparison of two regularized continuum models for concrete in the simulations of selected benchmarks of response to impact loading. Their overview is performed in the context of application in dynamics. The first one is the Hoffman viscoplastic consistency model, where the strain rate activates regularization. The second model is derived from the scalar damage theory enhanced by an averaging equation incorporating the Laplacian of an averaged strain measure. Both models are implemented in the FEAP package. The results of some standard wave propagation tests are discussed, considering discretization sensitivity and predicted failure modes. Three examples are pre- sented: the direct tension of a plain and reinforced concrete bar, the split test of a cylinder, and the four-point bending of a reinforced concrete beam. The ability of both models to simulate impact loading is assessed.

3

On spatial vs referential isotropic fourier’s law in finite deformation thermomechanics

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Wcisło B. , Pamin J. , Rose L. , Menzel A.

Engineering Transactions

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2023

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tom Vol. 71, iss. 1

111--140

EN

This paper deals with the issue of isotropic heat conduction in thermomechanical largestrain problems. The aim of the paper is a comparison of different variants of Fourier’s law used in the literature for a large strain problem. In particular, Fourier’s law is specified either in the reference or in the deformed configuration by using different options of heat flux density vectors which are presented and discussed. The paper includes working examples to illustrate the presented theory. Moreover, different formulations of Fourier’s law are tested by using the finite element method to investigate the influence of the applied variant on simulation results. The analysis reveals that in a strongly deformed area the temperature distribution varies.

4

Role of dilatancy angle in plasticity-based models of concrete

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Wosatko A. , Winnicki A. , Polak M. A. , Pamin J.

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2019

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tom Vol. 19, no. 4

1268--1283

EN

The so-called concrete damaged plasticity (CDP) model is frequently employed by ABAQUS users to simulate the behaviour of concrete. One important aspect of the model, namely the representation of material dilatancy, is evaluated in the paper. The role of the dilatancy angle in pressure-dependent plasticity models is reviewed. The plastic potential adopted in the CDP model is discussed. It is shown that the definitions of the angle in the CDP model and in the Burzynski–Drucker–Prager (BDP) plasticity model for a continuum can lead to different angle magnitudes. Two tests on concrete configurations are simulated to illustrate how strongly the angle influences the results: the Kupfer benchmark of a panel under uniaxial or biaxial compression and the punching shear response in a slab-column connection. The importance of viscosity in cracking simulation is thereby mentioned, the results are compared with experimental ones and mesh sensitivity is verified. Recommendations for analysis of concrete mechanics problems are formulated.