scholarly journals Dual rolls equal channel extrusion as unconventional SPD process of the ultralow-carbon steel: finite element simulation, experimental investigations and microstructural analysis

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
M. B. Jabłońska ◽  
K. Kowalczyk ◽  
M. Tkocz ◽  
T. Bulzak ◽  
I. Bednarczyk ◽  
...  
Keyword(s):  
Fracture Behaviour ◽  
Steel Strip ◽  
Deformation Behaviour ◽  
Microstructural Analysis ◽  
Dislocation Cell ◽  
Strength Properties ◽  
Experimental Investigations ◽  
Element Simulation ◽  
Steel Strength ◽  
Ultralow Carbon

AbstractThe paper presents results of FEM modelling as well as properties and microstructure of the ultralow-carbon ferritic steel after the unconventional SPD process—DRECE (dual rolls equal channel extrusion). Based on the conducted numerical simulation information about the deformation behaviour of a steel strip during the DRECE process was obtained. The simulation results were experimentally verified. The influence of DRECE process on hardness distribution, fracture behaviour and microstructure evolution of the investigated steel was analysed. The increase of steel strength properties after subsequent deformation passes was confirmed. The microstructural investigations revealed that the processed strips exhibit the dislocation cell microstructure and subgrains with mostly low-angle grain boundaries. The grains after processing had relatively high dislocation density and intense microband formation was observed. It was also proved that this unconventional SPD method fosters high grain refinement.

Experimental Investigations on Aluminium Ultrasonic Welding Parameters

2014 ◽  
Vol 657 ◽  
pp. 306-310
Author(s):  
Lăcrămioara Apetrei ◽  
Vasile Rață ◽  
Ruxandra Rață ◽  
Elena Raluca Bulai
Keyword(s):  
Microstructural Analysis ◽  
Base Material ◽  
Welding Process ◽  
Ultrasonic Welding ◽  
Experimental Investigations ◽  
Welding Parameters ◽  
Material Structure ◽  
Welding Temperature ◽  
Wide Range ◽  
Made In

Research evolution timely tendencies, in the nonconventional technologies field, are: manufacture conditions optimization and complex equipments design. The increasing of ultrasonic machining use, in various technologies is due to the expanding need of a wide range materials and high quality manufacture standards in many activity fields. This paper present a experimental study made in order to analyze the welded zone material structure and welding quality. The effects of aluminium ultrasonic welding parameters such as relative energy, machining time, amplitude and working force were compared through traction tests values and microstructural analysis. Microhardness tests were, also, made in five different points, two in the base material and three in the welded zone, on each welded aluminium sample. The aluminum welding experiments were made at the National Research and Development Institute for Welding and Material Testing (ISIM) Timişoara. The ultrasonic welding temperature is lower than the aluminium melting temperature, that's so our experiments reveal that the aluminium ultrasonic welding process doesn't determine the appearance of moulding structure. In the joint we have only crystalline grains deformation, phase transformation and aluminium diffusion.

MULTI-SCALE FINITE ELEMENT SIMULATION OF SEVERE PLASTIC DEFORMATION

2009 ◽  
Vol 23 (06n07) ◽  
pp. 1621-1626
Author(s):  
HYOUNG SEOP KIM
Keyword(s):  
Plastic Deformation ◽  
Finite Element ◽  
Severe Plastic Deformation ◽  
Constitutive Model ◽  
Dislocation Cell ◽  
Ultrafine Grain ◽  
Angular Pressing ◽  
Element Simulation ◽  
Ultrafine Grain Size ◽  
Ultrafine Grained

The technique of severe plastic deformation (SPD) enables one to produce metals and alloys with an ultrafine grain size of about 100 nm and less. As the mechanical properties of such ultrafine grained materials are governed by the plastic deformation during the SPD process, the understanding of the stress and strain development in a workpiece is very important for optimizing the SPD process design and for microstructural control. The objectives of this work is to present a constitutive model based on the dislocation density and dislocation cell evolution for large plastic strains as applied to equal channel angular pressing (ECAP). This paper briefly introduces the constitutive model and presents the results obtained with this model for ECAP by the finite element method.

Deformation and strength properties of some rocks in southern Ontario

1979 ◽  
Vol 16 (1) ◽  
pp. 108-120 ◽  
Author(s):  
K. Y. Lo ◽  
M. Hori
Keyword(s):  
Deformation Behaviour ◽  
Strength Properties ◽  
Compression Tests ◽  
Underground Structures ◽  
Southern Ontario ◽  
Analysis And Design ◽  
Rock Types ◽  
Anisotropic Elastic ◽  
Geological Formations ◽  
Independent Parameters

Uniaxial compression tests were performed on sedimentary rocks of five different geological formations at various sites in southern Ontario. The deformation behaviour is analysed in terms of the cross-anisotropic elastic theory and typical sets of five independent parameters for each rock unit have been obtained. It is shown that some of the rock types are significantly anisotropic both in deformation and strength behaviour. The practical relevance of the results in the analysis and design of underground structures in these rocks is discussed.

scholarly journals Effect of the Strain Rate on the Fracture Behaviour of High Pressure Pre-Charged Samples

Proceedings ◽  
2018 ◽  
Vol 2 (23) ◽  
pp. 1417
Author(s):  
Guillermo Álvarez Díaz ◽  
Tomás Eduardo García Suárez ◽  
Cristina. Rodríguez González ◽  
Francisco Javier Belzunce Varela
Keyword(s):  
Fracture Toughness ◽  
High Pressure ◽  
Hydrogen Embrittlement ◽  
Strain Rate ◽  
Fracture Behaviour ◽  
Structural Steels ◽  
Gaseous Hydrogen ◽  
Displacement Rate ◽  
Steel Strength ◽  
Fracture Tests

The aim of this work is to study the effect of the displacement rate on the hydrogen embrittlement of two different structural steels grades used in energetic applications. With this purpose, samples were pre-charged with gaseous hydrogen at 19.5 MPa and 450 °C for 21 h. Then, fracture tests of the pre-charged specimens were performed, using different displacement rates. It is showed that the lower is the displacement rate and the largest is the steel strength, the strongest is the reduction of the fracture toughness due to the presence of internal hydrogen.

scholarly journals Numerical Prediction Of The Effect Of Lamination Orientation On Fracture Behaviour Of Wires For Civil Engineering Applications

2014 ◽  
Vol 60 (4) ◽  
pp. 397-408
Author(s):  
K.K. Adewole ◽  
S.J. Bull
Keyword(s):  
Finite Element ◽  
Civil Engineering ◽  
Fracture Behaviour ◽  
Fe Analysis ◽  
Experimental Investigations ◽  
Engineering Applications ◽  
Steel Wires ◽  
Fracture Shape ◽  
Pointed End ◽  
Prediction Approach

AbstractThis paper presents a numerical investigation of the effects of lamination orientation on the fracture behaviour of rectangular steel wires for civil engineering applications using finite element (FE) analysis. The presence of mid-thickness across-the-width lamination changes the cup and cone fracture shape exhibited by the lamination-free wire to a V-shaped fracture with an opening at the bottom/pointed end of the V-shape at the mid-thickness across-the-width lamination location. The presence of mid-width across-the-thickness lamination changes the cup and cone fracture shape of the lamination-free wire without an opening to a cup and cone fracture shape with an opening at the lamination location. The FE fracture behaviour prediction approach adopted in this work provides an understanding of the effects of lamination orientation on the fracture behaviour of wires for civil engineering applications which cannot be understood through experimental investigations because it is impossible to machine laminations in different orientations into wire specimens.

Experimental Investigation and Finite Element Simulation of Fracture Process of Polymer Composite Material with Short Carbon Fibers

2015 ◽  
Vol 725-726 ◽  
pp. 943-948 ◽  
Author(s):  
Ivan Maniak ◽  
Boris Melnikov ◽  
Artem S. Semenov ◽  
Sergey Saikin
Keyword(s):  
Finite Element ◽  
Composite Material ◽  
Finite Element Simulation ◽  
Polymer Composite ◽  
Carbon Fibers ◽  
Strength Properties ◽  
Polymer Composite Material ◽  
Tension Tests ◽  
Element Simulation ◽  
Short Carbon

This work is devoted to the research of mechanical and strength properties of polymer composite material with short carbon fibers produced by injection molding technology. The material is PEEK90HMF20 with 20 % of carbon fibers mass fraction and based on polyether ether ketone (PEEK) polymer matrix. Mechanical and strength properties were researched on samples that had been cut from molded plates. A set of tension tests was performed and stress-strain diagrams of samples with different orientation in relation to the global direction of injection were obtained. Two-step homogenization procedure and pseudo-grains failure model were used to describe composite material behavior. The material model parameters were calibrated with experimental data by means of reverse-engineering procedure. Finite element simulation of tension tests was performed to check the quality of built model from the point of view of its ability to predict failure.

Experimental Investigation of Depletion- and Injection-Induced Changes in Poromechanical, Transport, and Strength Properties of High-Porosity Sandstone

SPE Journal ◽  
2021 ◽  
pp. 1-21
Author(s):  
Saeed Rafieepour ◽  
Stefan Z. Miska ◽  
Evren M. Ozbayoglu ◽  
Nicholas E. Takach ◽  
Mengjiao Yu ◽  
...  
Keyword(s):  
Pore Pressure ◽  
Effective Stress ◽  
Microstructural Analysis ◽  
Optical Microscope ◽  
Strength Properties ◽  
Rock Properties ◽  
Absolute Permeability ◽  
High Porosity ◽  
Confining Stress ◽  
Stress Changes

Summary In this paper, an extensive series of experiments was performed to investigate the evolution of poromechanical (dry, drained, undrained, and unjacketed moduli), transport (permeability), and strength properties during reservoir depletion and injection in a high-porosity sandstone (Castlegate). An overdetermined set of eight poroelastic moduli was measured as a function of confining pressure (Pc) and pore pressure (Pp). The results showed larger effect on pore pressure at low Terzaghi’s effective stress (nonlinear trend) during depletion and injection. Moreover, the rock sample is stiffer during injection than depletion. At the same Pc and Pp, Biot’s coefficient and Skempton’s coefficient are larger in depletion than injection. Under deviatoric loading, absolute permeability decreased by 35% with increasing effective confining stress up to 20.68 MPa. Given these variations in rock properties, modeling of in-situ-stress changes using constant properties could attain erroneous predictions. Moreover, constant deviatoric stress-depletion/injection failure tests showed no changes or infinitesimal variations of strength properties with depletion and injection. It was found that failure of Castlegate sandstone is controlled by simple effective stress, as postulated by Terzaghi. Effective-stress coefficients at failure (effective-stress coefficient for strength) were found to be close to unity (actual numbers, however, were 1.03 for Samples CS-5 and CS-9 and 1.04 for Sample CS-10). Microstructural analysis of Castlegate sandstone using both scanning electron microscope (SEM) and optical microscope revealed that the changes in poroelastic and transport properties as well as the significant hysteresis between depletion and injection are attributed to the existence and distribution of compliant components such as pores, microcracks, and clay minerals.

scholarly journals Effect of the Supports’ Positions on the Vibration Characteristics of a Flexible Rotor Shafting

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Miaomiao Li ◽  
Zhuo Li ◽  
Liangliang Ma ◽  
Rupeng Zhu ◽  
Xizhi Ma
Keyword(s):  
Finite Element ◽  
Finite Element Simulation ◽  
Vibration Characteristics ◽  
Rotor System ◽  
Experimental Investigations ◽  
Flexible Rotor ◽  
Bending Vibration ◽  
First Order ◽  
Element Simulation

In this study, we evaluated the effect of changing supports’ position on the vibration characteristics of a three-support flexible rotor shafting. This dependency was first analyzed using a finite element simulation and then backed up with experimental investigations. By computing a simplified rotor shafting model, we found that the first-order bending vibration in a forward whirl mode is the most relevant deforming mode. Hence, the effect of the supports’ positions on this vibration was intensively investigated using simulations and verified experimentally with a house-made shafting rotor system. The results demonstrated that the interaction between different supports can influence the overall vibration deformation and that the position of the support closer to the rotor has the greatest influence.

scholarly journals Improved design of roller linear guide for heavy load based on finite element method and measurement

2018 ◽  
Vol 10 (9) ◽  
pp. 168781401880015
Author(s):  
Xianchun Song ◽  
Hongjian Chen ◽  
Hongkui Jiang ◽  
Xiangrong Xu ◽  
Yanfeng Li ◽  
...  
Keyword(s):  
Finite Element ◽  
Sliding Friction ◽  
Design Method ◽  
Friction Torque ◽  
Experimental Investigations ◽  
Heavy Load ◽  
Linear Guide ◽  
Roller Guide ◽  
Element Simulation ◽  
Improved Design

Roller linear guides are key components in machine tool. The accuracy and efficiency of a machine toll are determined by the stiffness and friction torque of roller guide. This study proposes an improved design method for roller guide. The influences of the rollers profile on stiffness, stress distribution of roller linear guide are analyzed using finite element simulation. In this work, the design of the roller, slider, and the overall structure is modified. Moreover, experimental investigations on noise and sliding friction of roller linear guide are compared to validate the proposed design method. It seems that the proposed design can improve the dynamical performance of the roller linear guide.

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