scholarly journals Evaluation of the possibility of using the Drucker-Prager-Cap model in simulations of the densification process of shredded natural materials

2019 ◽  
Vol 254 ◽  
pp. 02018 ◽  
Author(s):  
Maciej Berdychowski ◽  
Krzysztof Talaśka ◽  
Dominik Wilczyński
Keyword(s):  
Plastic Deformation ◽  
Numerical Simulations ◽  
Experimental Studies ◽  
Densification Process ◽  
Waste Wood ◽  
Natural Materials ◽  
Preliminary Results ◽  
Special Construction ◽  
Cap Model

The article presents the preliminary results of numerical simulations of the densification process of shredded waste wood. The purpose of the simulation was to evaluate the possibility of using the Drucker-Prager-Cap model in the field of modeling plastic deformation of shredded biomaterials. The experimental studies allowed the verification of numerical simulations. In the research, the stamp-cylinder assembly of a special construction was used, adapted for assembly on a strength machine. The tests carried out are to constitute guidelines for the construction of machinery and devices for compacting biomass.

Redox Processes in Early Earth Accretion and in Terrestrial Bodies

Elements ◽  
2020 ◽  
Vol 16 (3) ◽  
pp. 161-166 ◽  
Author(s):  
Kevin Righter ◽  
Christopher D. K. Herd ◽  
Asmaa Boujibar
Keyword(s):  
Numerical Simulations ◽  
Liquid Water ◽  
Experimental Studies ◽  
Early Earth ◽  
Redox Processes ◽  
Natural Materials ◽  
The Earth

The Earth is a unique rocky planet with liquid water at the surface and an oxygen-rich atmosphere, consequences of its particular accretion history. The earliest accreting bodies were small and could be either differentiated and undifferentiated; later larger bodies had formed cores and mantles with distinct properties. In addition, there may have been an overall trend of early reduced and later oxidized material accreting to form the Earth. This paper provides an overview—based on natural materials in our Earthbound sample collections, experimental studies on those samples, and calculations and numerical simulations of differentiation processes—of planetary accretion, core–mantle equilibration, mantle redox processes, and redox variations in Earth, Mars, and other terrestrial bodies.

Vortex-Induced Vibrations of a Cylinder at Subcritical Reynolds Number

2011 ◽  
Author(s):  
Yoann Jus ◽  
Elisabeth Longatte ◽  
Jean-Camille Chassaing ◽  
Pierre Sagaut
Keyword(s):  
Reynolds Number ◽  
Numerical Simulations ◽  
Numerical Study ◽  
Damping Ratio ◽  
Experimental Studies ◽  
Cross Flow ◽  
Physical Analysis ◽  
Arbitrary Lagrangian Eulerian ◽  
Vortex Induced Vibrations ◽  
Low Mass

The present work focusses on the numerical study of Vortex-Induced Vibrations (VIV) of an elastically mounted cylinder in a cross flow at moderate Reynolds numbers. Low mass-damping experimental studies show that the dynamic behavior of the cylinder exhibits a three-branch response model, depending on the range of the reduced velocity. However, few numerical simulations deal with accurate computations of the VIV amplitudes at the lock-in upper branch of the bifurcation diagram. In this work, the dynamic response of the cylinder is investigated by means of three-dimensional Large Eddy Simulation (LES). An Arbitrary Lagrangian Eulerian framework is employed to account for fluid solid interface boundary motion and grid deformation. Numerous numerical simulations are performed at a Reynolds number of 3900 for both no damping and low-mass damping ratio and various reduced velocities. A detailed physical analysis is conducted to show how the present methodology is able to capture the different VIV responses.

Crashworthiness Performance of Mass-Efficient Extruded Structures

2002 ◽  
Author(s):  
Robert R. Mayer ◽  
Weigang Chen ◽  
Anil Sachdev
Keyword(s):  
Numerical Simulations ◽  
Single Cell ◽  
Experimental Testing ◽  
Experimental Studies ◽  
Nonlinear Material ◽  
Dynamic Strain ◽  
Cell Design ◽  
Explicit Finite Element ◽  
The One ◽  
Crushing Behavior

Theoretical, numerical and experimental studies were conducted on the axial crushing behavior of traditional single-cell and innovative four-cell extrusions. Two commercial aluminum alloys, 6061 and 6063, both with two tempers (T4 and T6), were considered in the study. Testing coupons taken from the extrusions assessed the nonlinear material properties. A theoretical solution was available for the one-cell design, and was developed for the mean crushing force of the four-cell section. Numerical simulations were carried out using the explicit finite element code LS-DYNA. The aluminum alloy 6063T4 was found to absorb less energy than 6061T4, for both the one-cell and four-cell configurations. Both 6061 and 6063 in the T6 temper were found to have significant fracture in the experimental testing. Theoretical analysis and numerical simulations predicted a greater number of folds for the four-cell design, as compared to the one-cell design, and this was confirmed in the experiments. The theoretical improvement in energy absorption of 57% for the four-cell in comparison with the one-cell design was confirmed by experiment. The good agreement between the theoretical, numerical and experimental results allows confidence in the application of the theoretical and numerical tools for both single-cell and innovative four-cell extrusions. It was also demonstrated that these materials have very little dynamic strain rate effect.

scholarly journals Plastic deformation simulation of steel panels

2019 ◽  
Vol 29 ◽  
pp. 02012
Author(s):  
Mihaela Savin ◽  
Adrian Presura ◽  
Ionel Chirica
Keyword(s):  
Plastic Deformation ◽  
Numerical Simulations ◽  
Fem Analysis ◽  
Vertical Displacement ◽  
Displacement Transducer ◽  
Force Transducer ◽  
Spherical Indenter ◽  
Steel Panel ◽  
Experimental Stand ◽  
Steel Panels

This paper presents the FEM analysis of plastic deformation of different steel panels using a spherical indenter. Two experiments were done: first on a simple steel panel and second on a stiffened steel panel, which were subjected to a static plastic deformation produced with help of a spherical indenter. The results of the practical test were compared with the results of numerical simulations, which were accomplished using ANSYS-Static Structural module. The tests were realized using an experimental stand based on a screw press mechanism. The tests consist in vertical displacement of the spherical bulb, which in this way deformed the panel leaning on the stand frame. During the tests were measured the force applied to the indenter, with help of an PLC500 force transducer, and the vertical displacement of the panel in the application point of force, with help of an HBM WA/300 displacement transducer. The results of calculations are presented below as: final deformed models and force-displacement diagrams with the comparison between experiment and numerical simulation. In conclusion of this research the compared results between the experiments and numerical simulations revealed that can be achieved accurate results using FEM analysis for plastic deformation problems, with proper parameters settings.

Hysteretic effects of dry friction: modelling and experimental studies

2007 ◽  
Vol 366 (1866) ◽  
pp. 747-765 ◽  
Author(s):  
Jerzy Wojewoda ◽  
Andrzej Stefański ◽  
Marian Wiercigroch ◽  
Tomasz Kapitaniak
Keyword(s):  
Numerical Simulations ◽  
Dry Friction ◽  
Experimental Studies ◽  
Friction Model ◽  
Hysteretic Effect ◽  
Motion Characteristic ◽  
Friction Models ◽  
Theoretical Analyses ◽  
Friction Modelling

In this paper, the phenomena of hysteretic behaviour of friction force observed during experiments are discussed. On the basis of experimental and theoretical analyses, we argue that such behaviour can be considered as a representation of the system dynamics. According to this approach, a classification of friction models, with respect to their sensitivity on the system motion characteristic, is introduced. General friction modelling of the phenomena accompanying dry friction and a simple yet effective approach to capture the hysteretic effect are proposed. Finally, the experimental results are compared with the numerical simulations for the proposed friction model.

Study of Surface Layer Hardening after Treatment Complex Tool

2020 ◽  
Vol 303 ◽  
pp. 89-96
Author(s):  
K.S. Mitrofanova
Keyword(s):  
Plastic Deformation ◽  
Surface Layer ◽  
Strain State ◽  
Experimental Studies ◽  
Surface Plastic Deformation ◽  
Surface Plastic ◽  
Technological Inheritance ◽  
Multiple Loading ◽  
Surface Layer Hardening ◽  
Solidified Body

The results of experimental studies of the thin surface layer of samples made of steel 45 after treatment with surface plastic deformation (SPD) multiradius roller (MR-roller) are presented. On the basis of the apparatus of the mechanics of technological inheritance, taking into account the effect of the solidified body, a model of the process according to the scheme of multiple loading-unloading of metal, taking into account the phenomenology of the SPD process and the properties of the material, is created. Distributions of parameters of the stress-strain state in the deformation centre are obtained, the parameters of roughness and microhardness of the surface layer are investigated.

scholarly journals Dynamo Action in Accretion Disks

1993 ◽  
Vol 157 ◽  
pp. 209-210
Author(s):  
Ulf Torkelsson
Keyword(s):  
Numerical Simulations ◽  
Accretion Disk ◽  
Accretion Disks ◽  
Standard Theory ◽  
Dynamo Action ◽  
Preliminary Results

Employing the standard theory for thin accretion disks I estimate the relevant parameters for a dynamo in an accretion disk. These estimates could then be compared to the results of numerical simulations. Some preliminary results of such simulations (Torkelsson & Brandenburg 1992) are presented too.

A Model to Predict the Effect of Pre-Strain on the Fracture Toughness of Line Pipe Steel

2002 ◽  
Author(s):  
Andrew Cosham ◽  
Naoto Hagiwara ◽  
Naoki Fukuda ◽  
Tomoki Masuda
Keyword(s):  
Fracture Toughness ◽  
Plastic Deformation ◽  
Theoretical Model ◽  
Plastic Strain ◽  
Ductile Fracture ◽  
Experimental Studies ◽  
Uniaxial Tensile ◽  
Stress Strain ◽  
Line Pipe ◽  
Strained Material

New and existing pipelines can be subjected to high plastic strains. Denting a pipeline causes permanent plastic deformation. Onshore pipelines subject to subsidence, frost heave or earthquake loading can experience significant plastic strain during service. Offshore pipelines that are reeled prior to laying, or are laid in deep water, or are operating at high temperatures and high pressures, can experience significant plastic strain both prior to, and during, service. Experimental studies have indicated that pre-strain (permanent plastic deformation) has a detrimental effect on the fracture toughness of steel; it reduces the resistance to crack initiation, reduces the resistance to crack growth, and increases the transition temperature. Consequently, there is a need for a thorough understanding of the effect of pre-strain on the fracture toughness of line pipe. Accordingly, a theoretical model for predicting the effect of tensile pre-strain on the ductile fracture toughness has been developed using the local approach. The effect of pre-strain is expressed in terms of an equation for the ratio of the fracture toughness of the pre-strained material to that of the virgin (not pre-strained) material. The model indicates that the effect of tensile pre-strain on the material’s fracture toughness can be characterised in terms of the effect of pre-strain on the stress-strain characteristics of the material, the critical fracture strain for a stress state corresponding to that during pre-strain, and several parameters that relate to the conditions for ductile fracture (or cleavage fracture). The implications of the model are that it may be possible to estimate the reduction in toughness caused by pre-strain simply from a full stress-strain curve of the virgin material. The model has been validated against the results of crack tip opening displacement (CTOD) tests conducted by Tokyo Gas on two line pipe steels subject to uniaxial tensile pre-strain. It is shown that the predictions and trends of the theoretical model are in broad agreement with the test results.

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