References of "Key Engineering Materials [=KEM]"
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See detailEffect of the kinematic hardening in the simulations of the straightening of long rolled profiles
Bouffioux, Chantal ULg; Boman, Romain ULg; Caillet, Nicolas et al

in Key Engineering Materials [=KEM] (2014), 611-612

Residual stresses and lack of straightness appear during the cooling of sheet piles where the initial temperature field is not homogeneous. To meet the standards, the long hot rolled pieces are ... [more ▼]

Residual stresses and lack of straightness appear during the cooling of sheet piles where the initial temperature field is not homogeneous. To meet the standards, the long hot rolled pieces are straightened using a series of rollers placed alternately above and below the pieces with shifts which create a succession of bendings. The process is modeled to study the impact of the industrial parameters ( the duration of the cooling and the rollers positions), to improve the final geometry and to reduce the residual stresses.Tests are carried out on this structural steel to observe the material behavior, then material laws are chosen and parameters of these laws are defined using and inverse method. Two sets of material data are obtained: for the first one, the hardening is supposed to be isotropic, and for the second one, additional tests are performed to describe isotropic and kinematic hardenings.The cooling followed by the straightening is then simulated by the finite element with these two sets of date. The comparison of the rollers forces, the deformation and the residual stresses show the impact of the kinematic hardening on such a process where the material undergoes a sucession of the tensions and compressions. The real forces applied by the rollers,the real curvature of the interlocks at the end of the straightening process and the distribution of the residual longitudinal stresses measured on the web using the ring core method are used to validate the numerical model. [less ▲]

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See detailNumerical simulations of asperity crushing using boundary conditions encountered in cold-rolling
Carretta, Yves ULg; Boman, Romain ULg; Legrand, Nicolas et al

in Key Engineering Materials [=KEM] (2013), 554-557

Asperity flattening has a huge influence on friction and wear in metal forming processes. Nevertheless, phenomena that occur at the microscopic scale are still not well understood. Since no experiment can ... [more ▼]

Asperity flattening has a huge influence on friction and wear in metal forming processes. Nevertheless, phenomena that occur at the microscopic scale are still not well understood. Since no experiment can be easily performed in real forming conditions, numerical models are essential to achieve a better knowledge of what happens in these contact regions. In this paper, two finite elements models are presented. The first one represents the flattening of a serrated asperity field in plane-strain conditions. The results are compared to the experiments published by Sutcliffe [1]. The second one is a tri-dimensional asperity model flattened by a rigid plane. The boundary conditions applied to this model correspond to the ones encountered in a real cold-rolling case. The results are compared to the relative contact area computed by a strip rolling model using the analytical laws proposed by Wilson & Sheu [2] and Marsault [3]. [less ▲]

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See detailNumerical simulation of a pyramid steel sheet formed by single point incremental forming using solid-shell finite elements
Duchene, Laurent ULg; Guzmán Inostroza, Carlos Felipe ULg; Behera, Amar Kumar et al

in Key Engineering Materials [=KEM] (2013)

Single Point Incremental Forming (SPIF) is an interesting manufacturing process due to its dieless nature and its increased formability compared to conventional forming processes. Nevertheless, the ... [more ▼]

Single Point Incremental Forming (SPIF) is an interesting manufacturing process due to its dieless nature and its increased formability compared to conventional forming processes. Nevertheless, the process suffers from large geometric deviations when compared to the original CAD profile. One particular example arises when analyzing a truncated two-slope pyramid. In this paper, a finite element simulation of this geometry is carried out using a newly implemented solid-shell element, which is based on the Enhanced Assumed Strain (EAS) and the Assumed Natural Strain (ANS) techniques. The model predicts the shape of the pyramid very well, correctly representing the springback and the through thickness shear (TTS). Besides, the effects of the finite element mesh refinement, the EAS and ANS techniques on the numerical prediction are presented. It is shown that the EAS modes included in the model have a significant influence on the accuracy of the results. [less ▲]

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See detailImplicit 2D Numerical Simulation of Materials Submitetd to High Strain Rates including Fracture
Jeunechamps, Pierre-Paul; Ponthot, Jean-Philippe ULg

in Key Engineering Materials [=KEM] (2013), 535-536

In this paper, we present a general consistent numerical formulation able to take into account strain rate and thermal effects of the material behavior. A thermomechanical implicit approach for element ... [more ▼]

In this paper, we present a general consistent numerical formulation able to take into account strain rate and thermal effects of the material behavior. A thermomechanical implicit approach for element erosion to model material failure is also presented. The numerical model will be illustrated by applications both from the metal forming and the impact domain. All these physical phenomena have been included in an implicit dynamic oriented object finite element code (implemented at LTAS-MN²L, University of Liège, Belgium) named Metafor [less ▲]

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See detailTowards fracture prediction in single point incremental forming
Guzmán Inostroza, Carlos Felipe ULg; Habraken, Anne ULg

in Key Engineering Materials [=KEM] (2013), 554-557

The stress state in metal forming processes usually implies low values of triaxiality. It is well known that damage models based only on triaxiality fails to capture the damage behavior properly, and ... [more ▼]

The stress state in metal forming processes usually implies low values of triaxiality. It is well known that damage models based only on triaxiality fails to capture the damage behavior properly, and recent articles have stressed the effect of the Lode parameter in describing damage. Moreover, in some process like incremental forming, the through thickness shear could dominate the rupture mechanism making the description, using solely the triaxiality, inaccurate. In this paper, a preliminary study of the stress state is carried over a near-to-failure single point incremental forming (SPIF) formed cone, through finite elements simulations using a newly developed solid-shell element. The results provide a basis for further studies into damage development in SPIF. [less ▲]

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See detailModeling thixoforming process using the eXtended Finite Element Method and the Arbitrary Lagrangian Eulerian formulation
Biotteau, Ewen; Bussetta, Philippe ULg; Ponthot, Jean-Philippe ULg

in Key Engineering Materials [=KEM] (2013), 554-557

In this contribution, one proposes a new strategy to model forming processes involving non-linear phenomena. The contact between the tool and the structure is enforced using a penalty approach. To free ... [more ▼]

In this contribution, one proposes a new strategy to model forming processes involving non-linear phenomena. The contact between the tool and the structure is enforced using a penalty approach. To free the user from the strict conforming between the structure and the mesh boundaries, one uses the level set and the extended finite element method for material/void interfaces. However, even if the finite element mesh does not need to conform with the boundaries, it still deforms with the structure. Then, an Arbitrary Lagrangian Eulerian formulation is introduced to relocate the mesh in its initial configuration and avoid distortions. From a user point of view, the whole calculation is then performed on a fixed Eulerian mesh. [less ▲]

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See detailEvaluation of the Enhanced Assumed Strain and Assumed Natural Strain in the SSH3D and RESS3 Solid Shell Elements for Single Point Incremental Forming Simulation
Guzmán Inostroza, Carlos Felipe ULg; Ben Bettaieb, Amine ULg; Velosa de Sena, José Ilidio et al

in Key Engineering Materials [=KEM] (2012), 504-506

Single Point Incremental Forming (SPIF) is a recent sheet forming process which can give a symmetrical or asymmetrical shape by using a small tool. Without the need of dies, the SPIF is capable to deal ... [more ▼]

Single Point Incremental Forming (SPIF) is a recent sheet forming process which can give a symmetrical or asymmetrical shape by using a small tool. Without the need of dies, the SPIF is capable to deal with rapid prototyping and small batch productions at low cost. Extensive research from both experimental and numerical sides has been carried out in the last years. Recent developments in the finite element simulations for sheet metal forming have allowed new modeling techniques, such as the Solid Shell elements, which combine the main features of shell hypothesis with a solid-brick element. In this article, two recently developed elements -SSH3D element [1, 2] and RESS3 element [3]- implemented in Lagamine (finite element code developed by the ArGEnCo department of the University of Liège) are explained and evaluated using the SPIF line test. To avoid locking problems, the well-known Enhanced Assumed Strain (EAS) and Assumed Natural Strain (ANS) techniques are used. The influence of the different EAS and ANS parameters are analysed comparing the predicted tool forces and the shape of a transversal cut, at the end of the process. The results show a strong influence of the EAS in the forces prediction, proving that a correct choice is fundamental for an accurate simulation of the SPIF using Solid Shell elements. [less ▲]

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See detailParticle packing density and limestone fillers for more sustainable cement
He, Huan ULg; Courard, Luc ULg; Pirard, Eric ULg

in Key Engineering Materials [=KEM] (2012), 517

Cement blending with mineral admixtures, especially with byproduct or waste product powder, can effectively reduce consumption of cement and promote the ecology. Recently, an innovative concept was ... [more ▼]

Cement blending with mineral admixtures, especially with byproduct or waste product powder, can effectively reduce consumption of cement and promote the ecology. Recently, an innovative concept was proposed to replace of “coarse” cement grains by the inert fillers for sustainable cement in the low w/c concrete cement. As a basic mechanism, particle packing plays an important role in such replacement or blending. In the first part of study, the paper discusses the particle packing aspect of cement grains, limestone filler (LF) and LF blended cement. The new developed wet packing method and a dry packing method are proposed for the evaluation purpose. The paper presents results of packing tests with the influences of PSD, cement type, vibration, mixing, blending proportions, etc. The advantages and limitations of two packing methods are also discussed in this paper. [less ▲]

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See detailMethodological approaches to 3D pore structure exploration
Stroeven, Piet; Le, L.B. Nghi; He, Huan ULg

in Key Engineering Materials [=KEM] (2012), 517

About 6% of global CO2 emissions are due to cement production. Blending of Portland cement with a significant fraction of mineral admixture could therefore be instrumental in reducing such emissions. Use ... [more ▼]

About 6% of global CO2 emissions are due to cement production. Blending of Portland cement with a significant fraction of mineral admixture could therefore be instrumental in reducing such emissions. Use of an admixture of vegetable origin such as rice husk as will additionally contribute to waste management and its incineration produces energy. This paper will stress the importance of properly designing such blends. Preferably gap-graded concepts should be employed, since blending efficiency in terms of strength development is promoted as shown in earlier publications. The paper therefore only briefly covers these aspects. Assessment of this blending concept on durability of cementitious materials constitutes a far more complicated problem. This requires careful porosimetry. Mostly, this problem is approached by MIP or by quantitative image analysis. Both can provide 3D information, although that of MIP is generally significantly biased. Quantitative image analysis is however time-consuming and laborious, and thus expensive. Moreover, it does not provide information on continuity of pores. Present day computer facilities offer therefore a better alternative. When using a proper DEM system, the concrete can be simulated in a realistic way. The paper describes new methods for investigating the pore structure in virtual concrete and presents some data on pure cement and blended cement. Differences will have impact on durability risks. [less ▲]

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See detailAsphalt concrete with fly ashes of different sources as filler replacement
Stroeven, Piet; He, Huan ULg; Huu Hanh, Pham

in Key Engineering Materials [=KEM] (2012), 517

Paper presents and discusses data obtained in a testing program on the replacement of limestone powder in asphalt concretes by fly ashes. This would combine economic, environmental and technical benefits ... [more ▼]

Paper presents and discusses data obtained in a testing program on the replacement of limestone powder in asphalt concretes by fly ashes. This would combine economic, environmental and technical benefits. The finest fly ash of Vietnamese origin scored best. This is proposed due to the gap-graded design of the particulate mixture of coarse crushed rock fractions, fine fluvial sand and the mineral admixture. The test program encompassed Marshall tests, creep tests and splitting tensile tests. [less ▲]

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See detailContinuous Roll Forming Simulation using Arbitrary Lagrangian Eulerian Formalism
Boman, Romain ULg; Ponthot, Jean-Philippe ULg

in Key Engineering Materials [=KEM] (2011), 473

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See detailNotched Specimens Fracture Prediction with an Advanced GTN Model
Fansi Tchonko, Joseph ULg; Ben Bettaieb, Mohamed ULg; Balan, Tudor et al

in Key Engineering Materials [=KEM] (2011), 488-489

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See detailModeling the vertical spincasting of large bimetallic rolling mill rolls
Studer, Léo ULg; Detrembleur, Sylvain ULg; Dewals, Benjamin ULg et al

in Key Engineering Materials [=KEM] (2010, June), 443

In order to take into account the dynamic effects of molten metal during solidification, a methodology is presented to interface a metal solidification solver (coupled thermal mechanical metallurgical ... [more ▼]

In order to take into account the dynamic effects of molten metal during solidification, a methodology is presented to interface a metal solidification solver (coupled thermal mechanical metallurgical finite elements solver) with a specifically developed flow dynamics solver. (flow dynamics and thermics finite volume solver) The numerical set of tools is designed to be used for the simulation of bimetallic hot rolling mill rolls vertical spincasting. Modeling the industrial process for these products imply certain specifications on the numerical methods used, mainly due to the size of the geometrical domain, low Rossby & Ekman numbers, and a high Reynolds number. [less ▲]

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See detailStudy of Dynamic Impact Behaviors and Ballistic Properties of Hybrid Composites
Guo, Yingnan; Sun, Qin; Wu, Ling ULg

in Key Engineering Materials [=KEM] (2010), 417-418

This paper deals with the ballistic properties of two kinds of hybrid composites: Kevlar/Carbon laminates and S-Glass/Carbon laminates. Twelve kinds of combinations of samples were made including various ... [more ▼]

This paper deals with the ballistic properties of two kinds of hybrid composites: Kevlar/Carbon laminates and S-Glass/Carbon laminates. Twelve kinds of combinations of samples were made including various fibers; various fiber orientations and various target thickness. Air-gun tests were carried out to determine the response of these combinations of hybrid laminates subject to impact loading. Compared with the test, an explicit finite element (FE) model was built with Pam-crash Code to simulate the impact process. The bullet was considered as a deformable body in contact with the composite shells. The Ladevèze model was used to describe the unidirectional properties of Carbon plies and Ladevèze fabric model was used to describe the homogeneous properties of the S-glass and Kevlar laminates. The influence of different parameters on the impact behavior of the two kinds of hybrid laminates was considered analytically. Results show very good agreement with the experimental data. Suggestions are also presented for the better hybrid mode to improve the ballistic properties. [less ▲]

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See detailAn Experimental Study on the Mechanical Performance and Damage Evolution of Woven Fabric E-glass Fiber Reinforced Epoxy Composite
Wu, Ling ULg; Guo, Yingnan; Li, Yulong

in Key Engineering Materials [=KEM] (2010), 417-418

The present study focuses on the mechanical performance and damage evolution of woven fabric E-glass fiber reinforced epoxy composite (7781/F155-glass/epoxy). For the identical behavior in the 0o and the ... [more ▼]

The present study focuses on the mechanical performance and damage evolution of woven fabric E-glass fiber reinforced epoxy composite (7781/F155-glass/epoxy). For the identical behavior in the 0o and the 90o directions of the tested material, the mechanical experiments were performed with 0o and 45o specimens. Three kinds of tests were implemented respectively: tension test with 0o specimen, compression test with 0o specimen, and tension test with 45o specimen which represents the in-plane shear test. Tension, compression and in-plane shear damage, which are defined as the decreasing ratio of modulus, were calculated from the data of quasi-static cyclic tests. The influence of loading rate on material behaviors were investigated under three different loading rates. Although all of the three loading rates are low, it showed that the strain rate has obvious effects on the ultimate strengths and moduli of the glass fiber reinforced epoxy composite. [less ▲]

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See detailHierarchically nanostructured porous functional ceramics
Vantomme, A.; Léonard, Alexandre ULg; Yuan, Z.-Y. et al

in Key Engineering Materials [=KEM] (2007), 336-338 III

We demonstrate here a self-formation phenomenon of hierarchy with multiple-scaled porosity. Macrochanneled structures, labelled as CMI-7, with openings ranging from 0.5 to 5.0 microns and wormhole-like ... [more ▼]

We demonstrate here a self-formation phenomenon of hierarchy with multiple-scaled porosity. Macrochanneled structures, labelled as CMI-7, with openings ranging from 0.5 to 5.0 microns and wormhole-like mesoporous walls with various ceramic compositions, such as ZrO2, TiO2, Al 2O3, Y2O3, ZrO2-SiO 2, ZrO2-Tio2, ZrO2-Y 2O3,..., aluminosilicates, aluminophosphates, silicoaluminophosphates, metallophosphates, can be prepared by just controlling the hydrolysis and polycondensation rates of the pre-selected ceramic sources. The macrochannels (funnel-like or straight) are well parallel each other and perpendicular to the tangent of the particles' surface. These hierarchical porous ceramics can be used in catalysis, separation and for immobilization of biological molecules and even microorganisms for filtration and bioreactor applications. [less ▲]

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See detailValidation of a new finite element for incremental forming simulation using a dynamic explicit approach
Henrard, Christophe ULg; Bouffioux, Chantal ULg; Duchene, Laurent ULg et al

in Key Engineering Materials [=KEM] (2007), 344

A new method for modeling the contact between the tool and the metal sheet for the incremental forming process was developed based on a dynamic explicit time integration scheme. The main advantage of this ... [more ▼]

A new method for modeling the contact between the tool and the metal sheet for the incremental forming process was developed based on a dynamic explicit time integration scheme. The main advantage of this method is that it uses the actual contact location instead of fixed positions, e.g. integration or nodal points. The purpose of this article is to compare the efficiency of the new method, as far as accuracy and computation time are concerned, with finite element simulations using a classic static implicit approach. In addition, a sensitivity analysis of the mesh density will show that bigger elements can be used with the new method compared to those used in classic simulations. [less ▲]

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See detailPlane strain test for metal sheet characterization
Flores, Paulo; Bonnet, Félix; Habraken, Anne ULg

in Key Engineering Materials [=KEM] (2007), 344

This article shows the influence of a plane strain test specimen geometry on the measurable strain field and the influence of free edge effects over the stress computation. The experimental strain field ... [more ▼]

This article shows the influence of a plane strain test specimen geometry on the measurable strain field and the influence of free edge effects over the stress computation. The experimental strain field distribution is measured over the whole deformable zone of a plane strain test specimen by an optical strain gauge. The chosen material is the DC06 IF steel of 0.8 mm thickness. The stress field is computed for several geometries at different strain levels by a Finite Element (FE) commercial code (Samcef ®). The results show that the stress field is sensitive to the specimen’s geometry and also to the tested material (strain field behavior is independent of material) and, based on results, an optimal specimen geometry is proposed in order to minimized the stress computation error. [less ▲]

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See detailTexturation of YBa2Cu3O7-delta thick films by electrophoretic deposition under magnetic field
Dusoulier, Laurent; Denis, Samuel ULg; Nutal, Nicolas ULg et al

in Key Engineering Materials [=KEM] (2006), 314

YBa2Cu3O7-delta coatings were deposited by electrophoretic deposition (EPD) onto Ni substrates. Particles of different sizes and shapes were used in order to study the influence of the powder ... [more ▼]

YBa2Cu3O7-delta coatings were deposited by electrophoretic deposition (EPD) onto Ni substrates. Particles of different sizes and shapes were used in order to study the influence of the powder microstructure on the film density. Texturation of the thick films was induced by application of a magnetic field during the electrophoretic deposition. X-ray diffraction analysis has clearly shown preferred c-axis alignment of the YBa2Cu3O7-delta films along the direction normal to the substrate surface. Scanning electron microscopy and optical polarised light microscopy were used to characterise the microstructure of the coatings, revealing a nonrandom platelets organisation. [less ▲]

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See detailPreparation of nanosized barium zirconate powder by precipitation in aqueous solution
Boschini, Frédéric ULg; Guillaume, Bernard ULg; Rulmont, André ULg et al

in Key Engineering Materials [=KEM] (2004), 264-268(Part 1-3), 2335-2338

Several ways were explored to synthesize barium zirconate by soft chemistry methods in aqueous solution. In the first method the synthesis of barium zirconate was initiated by urea decomposition, through ... [more ▼]

Several ways were explored to synthesize barium zirconate by soft chemistry methods in aqueous solution. In the first method the synthesis of barium zirconate was initiated by urea decomposition, through an homogeneous precipitation of barium and zirconium salts followed by a "low temperature" thermal treatment. The kinetic of the reaction and the optimum urea/cation ratio have been determined by means of X-ray diffraction and Inductive Coupled Plasma analyses. It has been demonstrated that an amorphous zirconium hydrated oxide starts to precipitate followed by the precipitation of barium carbonate[1]. A calcination at 1200degreesC during 2 hours gives rise to the formation of a pure barium zirconate phase. In the other methods, barium zirconate was synthesized, in one step without any thermal treatments, by precipitation in highly basic aqueous solutions containing barium and zirconium salts. The effect of the hydroxide concentration was discussed in relation to the barium zirconate phase formation, the particles size and the particles size distribution. For each powder, microstructural characterisations have been performed on sintered bodies in order to evaluate the influence of the thermal treatment on the final density. Dilatometric measurements have been also performed in order to quantify the densification process. Important informations were obtained by these techniques, as for example the existence of an internal porosity which severely limits the final density of the material, even if sintering was performed at high temperature. Thus a careful control of the heating profile seems to be necessary in order to produce dense materials. [less ▲]

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