Wyniki wyszukiwania - BazTech

1

Possible means of overcoming sedimentation by motile sea-picoplankton cells

Pundyak O.

Oceanologia

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2017

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No. 59 (2)

108--112

EN

A model for overcoming the gravity by sea-picoplankton cells is proposed here. It is based on different means of escaping from potential predators used by cells of co-existing picoplankton species. These different means cause friction anisotropy of motile cells with strong antipredator behavior (AB). According to equations of stochastic movement used in this model for picoplankton cells with strong AB, collocated with high concentration of cells with weak or absent AB, the sedimentation can be considerably overcome.

2

A 3D numerical modeling of hemispherical contact against an elastic-plastic flat surface

Trzepieciński T., Stachowicz F., Bosiakov S., Rogosin S.

Zeszyty Naukowe Politechniki Rzeszowskiej. Mechanika

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2014

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z. 86 [290], nr 4

629--638

EN

This paper presents a method of determining the anisotropic friction model for sheet metal forming processes based on experimental data obtained from the pin-on-disk tribometer test. The frictional investigations presented in this work were conducted for deep drawing quality cold-rolled steel sheet. The anisotropic friction model corresponded to experimental results was implemented into a finite element (FE) model built using the ABAQUS software. In the numerical investigations the hemispherical contact against an elastic-plastic flat was analysed. Both material and friction anisotropy influenced the non-uniformity of the stress distribution around the hemisphere axis, which is clearly visible for higher values of hemispherical solid indentations. It was found that the change of isotropic friction to anisotropic conditions for both material models slightly influences – the value and change of equivalent plastic strain distribution in contact zone.

PL

Artykuł prezentuje metodę wyznaczania anizotropowego modelu tarcia dla procesów kształtowania blach na podstawie danych eksperymentalnych otrzymanych w próbie trobotestera o skojarzeniu trzpień na tarczy. Badania tarciowe przedstawione w pracy wykonano dla zimno-walcowanych blach stalowych głęboko tłocznych. Anizotropowy model tarcia odpowiadający wynikom eksperymentalnym zaimplementowano do modelu elementów skończonych z wykorzystaniem programu ABAQUS. W badaniach numerycznych analizowano kontakt powierzchni półkulistej ze sprężysto-plastyczną powierzchnią płaską. Anizotropia materiału oraz tarcia wpływa na nierównomierność rozkładu naprężeń dookoła osi półkuli, co jest wyraźnie widoczne dla większych zagłębień bryły półkulistej. Zmiana modelu tarcia z izotropowego na anizotropowy nieznacznie wpływa na wartość i zmianę rozkładu naprężeń oraz odkształceń zastępczych w strefie kontaktu.

3

Modelling of friction anisotropy of deepdrawing sheet in ABAQUS/EXPLICIT

Stachowicz F., Trzepieciński T.

Archives of Foundry Engineering

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2010

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Vol. 10, iss. 3 spec.

47--52

EN

This paper presents the experimental and numerical results of rectangular cup drawing of steel sheets. The aim of the experimental study was to analyze material behavior under deformation. The received results were further used to verify the results from numerical simulation by taking friction and material anisotropy into consideration. A 3D parametric finite element (FE) model was built using the commercial FE-package ABAQUS/Standard. ABAQUS allows analyzing physical models of real processes putting special emphasis on geometrical non-linearities caused by large deformations, material non-linearities and complex friction conditions. Frictional properties of the deep drawing quality steel sheet were determined by using the pin-on-disc tribometer. It shows that the friction coefficient value depends on the measured angle from the rolling direction and corresponds to the surface topography. A quadratic Hill anisotropic yield criterion was compared with Huber-Mises yield criterion having isotropic hardening. Plastic anisotropy is the result of the distortion of the yield surface shape due to the material microstructural state. The sensitivity of constitutive laws to the initial data characterizing material behavior is also presented. It is found that plastic anisotropy of the matrix in ductile sheet metal has influence on deformation behavior of the material. If the material and friction anisotropy are taken into account in the finite element analysis, this approach undoubtedly gives the most approximate numerical results to real processes. This paper is the first part of the study of numerical investigation using ABAQUS and mainly deals with the most influencing parameters in a forming process to simulate the sheet metal forming of rectangular cup.

4

3D elasto-plastic FEM analysis of the sheet drawing of anisotropic steel sheet

Trzepieciński T.

Archives of Civil and Mechanical Engineering

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2010

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Vol. 10, no 4

95-106

EN

The article presents the experimental and numerical results of rectangular cup drawing of DC03 coldrolled steel sheet. The aim of the experimental study was to analyse material behaviour under deformation. The received numerical results were further verified by experimental results. A 3D parametric finite element model was built using the commercial package ABAQUS. If the material and friction anisotropy are taken into account in the numerical model, this approach undoubtedly gives the most approximate numerical results to real processes.

PL

W pracy przedstawiono wyniki badań eksperymentalnych oraz symulacji numerycznych procesu kształtowania wytłoczek z blachy stalowej głębokotłocznej. Celem badań eksperymentalnych była analiza płynięcia materiału pod wpływem deformacji plastycznej. Otrzymane wyniki symulacji numerycznych zostały zweryfikowane z wynikami eksperymentalnymi. Model numeryczny 3D, bazujący na metodzie elementów skończonych, zbudowano w programie ABAQUS. Uwzględnienie w modelu numerycznym anizotropii plastycznej materiału oraz anizotropii tarcia warunkuje otrzymanie wyników bardziej zbliżonych do wyników rzeczywistego procesu kształtowania.

5

Asymmetric Continuum and Anisotropy

Teisseyre R.

Acta Geophysica

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2006

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Vol. 54, no. 3

225-238

EN

We present a relation between stress moments and antisymmetric part of stresses and the related constitutive law joining those stresses with the particle/point rotations. Correspondence of the asymmetric continuum theory to the micromorphic theory is considered. An extension of the asymmetric continuum theory for the case of 2D anisotropy for antisymmetric stresses leads us to the problems of friction ani-sotropy and fracture pattern.