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See detailExperimental Analysis of the Bifurcation Behaviour of a Bridge Deck Undergoing Across-Wind Galloping
Andrianne, Thomas ULg; Dimitriadis, Grigorios ULg

in De Roeck, G.; Degrande, G.; Lombaert, G. (Eds.) et al Proceedings of the 8th International Conference on Structural Dynamics, EURODYN 2011 (2011, July 05)

The phenomenon of aeroelastic galloping is a very important design consideration for bridges and other slender structures. It has been investigated by a number of researchers but, most frequently, the ... [more ▼]

The phenomenon of aeroelastic galloping is a very important design consideration for bridges and other slender structures. It has been investigated by a number of researchers but, most frequently, the analysis is limited to quasi-steady aerodynamic and linearized aeroelastic considerations. Such treatment has been shown to be effective for simple cross-sectional shapes, such as rectangles. In this work, an aeroelastic model of a realistic bridge deck cross-section is tested in a low speed wind tunnel. Both static and dynamic tests are carried out and the resulting force and vibration measurements are presented. The static force results are used to set up a quasi-steady mathematical model. The dynamic responses are used to draw a complete bifurcation diagram within a chosen airspeed range and to discuss the stability of the system. It is shown that the experimental system undergoes a subcritical Hopf bifurcation, its phase space including both a stable and an unstable limit cycle. As consequence, throughout the chosen airspeed, the system can either remain stable or undergo limit cycle oscillations. The quasi-steady analysis fails completely in capturing this type of behaviour. The predicted galloping onset speed is too conservative and the predicted oscillation amplitudes too high. The reason for this failure is the fact that the quasi-steady mathematical model is incapable of modelling subcritical Hopf bifurcations. [less ▲]

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See detailExperimental Analysis of the Effects of Particulate Fouling on Heat Exchanger Heat Transfer and Air-Side Pressure Drop for a Hybrid Dry Cooler
Bell, Ian ULg; Groll, Eckhard; Konig, Holger

in Heat Transfer Engineering (2011), 32

It is well known that significant fouling by particulate matter can have a deleterious effect on the performance of enhanced surface heat exchangers, and the same is true for hybrid heat exchangers ... [more ▼]

It is well known that significant fouling by particulate matter can have a deleterious effect on the performance of enhanced surface heat exchangers, and the same is true for hybrid heat exchangers. Hybrid heat exchangers are heat exchangers which are typically run in dry mode to reject heat. When the ambient conditions require more heat rejection than can be provided by sensible heat transfer a water pump is turned on and water flows over the fins and the evaporation of water provides a further cooling effect. Fouling in dry mode operation is physically similar to that of air-cooled heat exchangers, but in evaporative mode the flow of the water over the coil eliminates the impact of fouling. A hybrid dry cooler heat exchanger of 60 cm x 60 cm frontal area has been installed in a well-instrumented wind tunnel to measure the heat exchanger’s performance. Hot water flows through the coil to provide the load, and air flows over the coil to provide cooling. During evaporative mode operation another stream of water flows over the outside face of the coil, adhering mainly to the louvered fins. The louvered fins are specially designed for optimized water flow during wetting mode. The fins are made of aluminum, the tubes are copper, and protection against corrosion is realized by a special E-coating. This coil has been tested clean and fouled with ASHRAE standard dust, for both dry and wet operation. Results are presented for the air side pressure drop and overall heat transfer conductance of the coil under all conditions for which 50% increases in air-side pressure drop are found under heavy fouling. The influence of fouling on heat transfer is small. Also, using the wetting water to wash the fouling off the coil is investigated, and found to be of some limited utility. [less ▲]

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See detailExperimental analysis of the stability of coarse sediments
Duma, Diana ULg; Erpicum, Sébastien ULg; Archambeau, Pierre ULg et al

in Symposium on Two-phase Modelling for Sediment Dynamics in Geophysical Flows (2013, June 12)

To predict the inception of sediment motion, Shields diagram remains the most widely used criterion in engineering practice so far. However, this approach faces several limitations and a number of gaps in ... [more ▼]

To predict the inception of sediment motion, Shields diagram remains the most widely used criterion in engineering practice so far. However, this approach faces several limitations and a number of gaps in knowledge still remain. The present research aims to provide new knowledge about the inception of motion in rivers with coarse sediments. A series of experiments was conducted in a flume horizontal 6 m long and 15 cm wide. The bottom was paved, either entirely or partly, with gravels of approximately 12 mm in diameter. Ultrasonic sensors were used to measure the water depth, a flowmeter for the discharge, an ultrasonic velocity profiler (UVP) transducer for the flow velocity. Three different thresholds were defined to distinguish between the following states: no motion, vibration of stones, local motion, and large scale motion. The overwhelming influence of turbulence was emphasized by the conducted tests. This paper details the results of these experiments and demonstrates the need for further research in order to better quantify these effects. [less ▲]

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See detailExperimental and analytical investigations on single-sided composite joint configuration
Demonceau, Jean-François ULg; Jaspart, Jean-Pierre ULg

in Walraven, Joost; Blaauwendraad, Johan; Scarpas, Tom (Eds.) et al 5th International PhD Symposium in Civil Engineering (2004, June 16)

For three years, in the framework of a European research project funded by the European Community for Steel and Coal (ECSC) in which the Liège University was deeply involved, intensive experimental ... [more ▼]

For three years, in the framework of a European research project funded by the European Community for Steel and Coal (ECSC) in which the Liège University was deeply involved, intensive experimental, numerical and theoretical investigations have been carried out on the behaviour of composite sway buildings under static and seismic loading. This paper presents experimental and analytical studies carried out at Liège University, as part of the above European project, with the objective to investigate the behaviour of a single-sided composite joint configuration under static loading. A particular failure mode occurred during the experimental tests, which had not yet been detected previously; it is described in details. Then, an analytical formula covering this particular phenomenon and based on a theoretical model is presented; it is validated through comparisons with experimental results. [less ▲]

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See detailExperimental and analytical investigations on the behaviour of building frames further to a column loss
Demonceau, Jean-François ULg; Jaspart, Jean-Pierre ULg

in Mazzolani, F.; Mistakidis, E.; Borg, R. P. (Eds.) et al Urban Habitat Constructions under Catastrophic Events (2008, October 23)

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See detailExperimental and analytical investigations on the response of structural building frames further to a column loss
Demonceau, Jean-François ULg; Jaspart, Jean-Pierre ULg

(2009, May)

Recent events such as natural catastrophes or terrorism attacks have highlighted the necessity to ensure the structural integrity of buildings under exceptional events. Design requirements are proposed in ... [more ▼]

Recent events such as natural catastrophes or terrorism attacks have highlighted the necessity to ensure the structural integrity of buildings under exceptional events. Design requirements are proposed in some codes but are generally not satisfactory. In particular, it is not demonstrated that, even if these requirements are respected, a structure subjected to an exceptional event will really behave properly. A European RFCS project called “Robust structures by joint ductility” has been set up in 2004, for three years, with the aim to provide requirements and practical guidelines so as to ensure the structural integrity of steel and composite structures under exceptional events through an appropriate robustness. The investigations performed at the University of Liège, as part of this European project, are mainly dedicated to the exceptional event “loss of a column in a steel or steel-concrete composite building frame”; the main objective is to develop a simplified analytical procedure to predict the frame response further to a column loss. The development of this simplified procedure is detailed in two complementary PhD theses: the thesis of Demonceau J.-F. and the thesis of Luu N.N.H. Present paper describes experimental and analytical studies carried out in [Demonceau, 2008]. In particular, a simplified analytical procedure for the prediction of the global frame response when significant membrane forces develop further to a column loss will be described; it allows: (i) to predict the development of the catenary action in a frame with joints subjected to combined bending moment and tension loads and (ii) to compute the requested rotation capacity at the joint level according to the loads applied on the frame. [less ▲]

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See detailExperimental and computational micro–mechanical investigations of compressive properties of polypropylene/multi–walled carbon nanotubes nanocomposite foams
Wan, Fangyi; Tran, Minh Phuong; Leblanc, Christophe ULg et al

in Mechanics of Materials (2015), 91(Part 1), 95-118

The compressive behavior of nanocomposite foams is studied by both experimental and computational micro-mechanics approaches with the aim of providing an efficient computational model for this kind of ... [more ▼]

The compressive behavior of nanocomposite foams is studied by both experimental and computational micro-mechanics approaches with the aim of providing an efficient computational model for this kind of material. The nanocomposites based on polypropylene (PP) and different contents of multi-walled carbon nanotubes (CNTs) are prepared by melt mixing method. The nanocomposite samples are foamed using super-critical carbon dioxide (ScCO2) as blowing agent at different soaking temperatures. The influence of this foaming parameter on the morphological characteristics of the foam micro-structure is discussed. Differential Scanning Calorimetry (DSC) measurements are used to quantify the crystallinity degree of both nanocomposites and foams showing that the crystallinity degree is reduced after the foaming process. This modification leads to mechanical properties of the foam cell walls that are different from the raw nanocomposite PP/CNTs material. Three--point bending tests are performed on the latter to measure the flexural modulus in terms of the crystallinity degree. Uniaxial compression tests are then performed on the foamed samples under quasi-static conditions in order to extract the macro-scale compressive response. Next, a two-level multi-scale approach is developed to model the behavior of the foamed nanocomposite material. On the one hand, the micro-mechanical properties of nanocomposite PP/CNTs cell walls are evaluated from a theoretical homogenization model accounting for the micro-structure of the semi-crystalline PP, for the degree of crystallinity, and for the CNT volume fraction. The applicability of this theoretical model is demonstrated via the comparison with experimental data from the described experimental measurements and from literature. On the other hand, the macroscopic behavior of the foamed material is evaluated using a computational micro-mechanics model using tetrakaidecahedron unit cells and periodic boundary conditions to estimate the homogenized properties. The unit cell is combined with several geometrical imperfections in order to capture the elastic collapse of the foamed material. The numerical results are compared to the experimental measurements and it is shown that the proposed unit cell computational micro-mechanics model can be used to estimate the homogenized behavior, including the linear and plateau regimes, of nanocomposite foams. [less ▲]

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See detailExperimental and computational study of the correlation between oxygen tension, cell viability and proliferation in fibrin hydrogels
Demol, J.; Lambrechts, D.; Geris, Liesbet ULg et al

in Proceedings of the 17th conference of the European Society of Biomechanics (2010)

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See detailExperimental and Computational Study of the Structural and Electronic Properties of Fe II(2,20-bipyridine)(mes) 2 and [Fe II(2,20-bipyridine)(mes) 2] -, a Complex Containing a 2,20-Bipyridyl Radical Anion
Irwin, Mark; Jenkins, Rhiannon; Denning, Mark et al

in Inorganic Chemistry (2010), 49

Addition of potassium metal and 2,2,2-crypt (4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane) to a tetrahydrofuran (THF) solution of Fe(2,20 -bipyridine)(mes)2 (1; mes = 2,4,6-Me3C6H2) yielded ... [more ▼]

Addition of potassium metal and 2,2,2-crypt (4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane) to a tetrahydrofuran (THF) solution of Fe(2,20 -bipyridine)(mes)2 (1; mes = 2,4,6-Me3C6H2) yielded the anionic complex [Fe(2,20 -bipyridine)(mes)2] - which was isolated as [K(2,2,2-crypt)][Fe(2,20 -bipyridine)(mes) 2](2) alongside the side-product [K(2,2,2-crypt)][Fe(mes)3] 3 C6H12 (3). A compositionally pure sample of 2 was obtained by dissolving a mixture of 2 and 3 in dry pyridine and layering the resulting solution with toluene. Solid state magnetic susceptibility measurements on 1 reveal Curie-Weiss paramagnetic behavior with a molar magnetic moment of 5.12(1) μB between 20 and 300 K, a value which is in line with the expected iron(II) spin-only value of 4.90 μB. The magnetic measurements carried out on 2 reveal more complex temperature dependent behavior consistent with intramolecular antiferromagnetic coupling (J=-46 cm -1) between the unpaired electrons of the iron(II) ion (S Fe =2) and a π* orbital of the bipyridyl radical (Sbipy = 1/2). Structural data, M€ossbauer and electron paramagnetic resonance (EPR) spectroscopic measurements, and density functional theory (DFT) calculations are all consistent with this model of the electronic structure. To the best of our knowledge, species 2 represents the first crystallographically characterized transition metal complex of the 2,20 -bipyridyl ligand for which magnetic, spectroscopic, and computational data indicate the presence of an unpaired electron in the π* antibonding orbital. [less ▲]

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See detailExperimental And Conformational Analyses Of Interactions Between Butenafine And Lipids
Mingeot-Leclercq, Mp.; Gallet, X.; Flore, Christelle ULg et al

in Antimicrobial Agents and Chemotherapy (2001), 45(12), 3347-54

Butenafine (N-4-tert-butylbenzyl-N-methyl-1-naphtalenemethylamine hydrochloride) is an antifungal agent of the benzylamine class that has excellent therapeutic efficacy and a remarkably long duration of ... [more ▼]

Butenafine (N-4-tert-butylbenzyl-N-methyl-1-naphtalenemethylamine hydrochloride) is an antifungal agent of the benzylamine class that has excellent therapeutic efficacy and a remarkably long duration of action when applied topically to treat various mycoses. Given the lipophilic nature of the molecule, efficacy may be related to an interaction with cell membrane phospholipids and permeabilization of the fungal cell wall. Similarly, high lipophilicity could account for the long duration of action, since fixation to lipids in cutaneous tissues might allow them to act as local depots for slow release of the drug. We have therefore used computer-assisted conformational analysis to investigate the interaction of butenafine with lipids and extended these observations with experimental studies in vitro using liposomes. Conformational analysis of mixed monolayers of phospholipids with the neutral and protonated forms of butenafine highlighted a possible interaction with both the hydrophilic and hydrophobic domains of membrane phospholipids. Studies using liposomes demonstrated that butenafine increases membrane fluidity [assessed by fluorescence polarization of 1-(4-trimethylammonium-phenyl)-6-phenyl-1,3,5-hexatriene and 1,6-diphenylhexatriene] and membrane permeability (studied by release of calcein from liposomes). The results show, therefore, that butenafine readily interacts with lipids and is incorporated into membrane phospholipids. These findings may help explain the excellent antifungal efficacy and long duration of action of this drug when it is used as a topical antifungal agent in humans. [less ▲]

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See detailExperimental and in silico approaches to study the interaction of Remorin with plant plasma membrane : specific interaction of the C-term domain with lipids
Deleu, Magali ULg; Nasir, Mehmet Nail ULg; Gronnier, Julien et al

Conference (2015, September 29)

The function of Remorins, a diverse family of plant-specific proteins (1) is far to be fully elucidated. One of them, StREM1.3 (for Solanum tuberosum Remorin from group 1, homolog 3) has been reported to ... [more ▼]

The function of Remorins, a diverse family of plant-specific proteins (1) is far to be fully elucidated. One of them, StREM1.3 (for Solanum tuberosum Remorin from group 1, homolog 3) has been reported to regulate cell-to-cell propagation of the potato virus X (2). It was also shown to be localized to the inner leaflet of plasma membranes (PMs) and along plasmodesmata, bridges connecting neighbor cells essential for cell-to-cell communication in plants (3). The mechanisms driving StREM1.3 association with PM is still an open question. It was shown recently that a domain of 28 residues at the C-terminus of the potato (RemCA) is required and sufficient for anchoring to the PM (4). Here we combined experimental and in silico biophysics to unravel the molecular bases of RemCA membrane binding. Biomimetic membrane models of plant PM such as monolayers and liposomes were used with various biophysical techniques (Langmuir monolayer technique, Fourier-transformed infrared spectroscopy, circular dichroïsm) and modeling tools (home-made methods and molecular dynamics) (5) to answer to three questions: (i) What is the conformation adopted by RemCA within a membrane?, (ii) Is there any membrane lipid specificity in the RemCA-membrane binding? (iii) What is the role of the two different RemCA domains in the interaction? Results show that RemCA displays a preference for plant phosphoinositide and sitosterol-enriched inner leaflet plasma membrane rafts. Within the membrane, the C-terminal and the N-terminal domains adopt a random coil and a -helical conformation respectively. The C-terminal domain acts as a driver to bind RemCA to the membrane while the N-terminal domain stabilizes the peptide at the membrane. Lysine residues have a crucial importance in this interaction. References (1) Raffaele et al., Plant Physiol., 2007, 145: 593–600 (2) Raffaela et al., Plant Cell, 2009, 21: 1541–1555. (3) Maule, Curr. Opin. Plant Biol., 2008, 11: 680–686. (4) Perraki et al., Plant Physiology, 2012, 160 : 624-637. (5) Deleu et al., Biochim. Biophys. Acta – Biomembranes, 2014, 1838 : 3171-3190. [less ▲]

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See detailAn experimental and numerical analysis of effects induced by moving bodies in free surface water
Kerger, François ULg; Detrembleur, Sylvain ULg; Archambeau, Pierre ULg et al

in Pagliara Stefano (Ed.) Hydraulic Structures (2008)

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See detailExperimental and numerical analysis of flow instabilities in rectangular shallow basins
Dewals, Benjamin ULg; Kantoush, Sameh; Erpicum, Sébastien ULg et al

in Environmental Fluid Mechanics (2008), 8(1), 31-54

Free surface flows in several shallow rectangular basins have been analyzed experimentally, numerically and theoretically. Different geometries, characterized by different widths and lengths, are ... [more ▼]

Free surface flows in several shallow rectangular basins have been analyzed experimentally, numerically and theoretically. Different geometries, characterized by different widths and lengths, are considered as well as different hydraulic conditions. First, the results of a series of experimental tests are briefly depicted. They reveal that, under clearly identified hydraulic and geometrical conditions, the flow pattern is found to become nonsymmetric, in spite of the symmetrical inflow conditions, outflow conditions and geometry of the basin. This non-symmetric motion results from the growth of small disturbances actually present in the experimental initial and boundary conditions. Second, numerical simulations are conducted based on a depth-averaged approach and a finite volume scheme. The simulation results reproduce the global pattern of the flow observed experimentally and succeed in predicting the stability or instability of a symmetric flow pattern for all tested configurations. Finally, an analytical study provides mathematical insights into the conditions under which the symmetric flow pattern becomes unstable and clarifies the governing physical processes. [less ▲]

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See detailExperimental and numerical analysis of flow instabilities in rectangular shallow basins
Dewals, Benjamin ULg

Scientific conference (2007, March 29)

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See detailAn experimental and numerical analysis of the HCCI auto-ignition process of primary reference fuels, toluene reference fuels and diesel fuel in an engine, varying the engine parameters
Machrafi, Hatim ULg; Cavadias, Simeon; Gilbert, Philippe

in Fuel Processing Technology (2008), 89(11), 1007-1016

For a future HCCI engine to operate under conditions that adhere to environmental restrictions, reducing fuel consumption and maintaining or increasing at the same time the engine efficiency, the choice ... [more ▼]

For a future HCCI engine to operate under conditions that adhere to environmental restrictions, reducing fuel consumption and maintaining or increasing at the same time the engine efficiency, the choice of the fuel is crucial. For this purpose, this paper presents an auto-ignition investigation concerning the primary reference fuels, toluene reference fuels and diesel fuel, in order to study the effect of linear alkanes, branched alkanes and aromatics on the auto-ignition. The auto-ignition of these fuels has been studied at inlet temperatures from 25 to 120 degrees C, at equivalence ratios from 0.18 to 0.53 and at compression ratios from 6 to 13.5, in order to extend the range of investigation and to assess the usability of these parameters to control the auto-ignition. It appeared that both iso-octane and toluene delayed the ignition with respect to n-heptane, while toluene has the Strongest effect. This means that aromatics have higher inhibiting effects than branched alkanes. In an increasing order, the inlet temperature, equivalence ratio and compression ratio had a promoting effect on the ignition delays. A previously experimentally validated reduced surrogate mechanism, for mixtures of n-heptane, iso-octane and toluene, has been used to explain observations of the auto-ignition process. (C) 2008 Elsevier B.V. All rights reserved. [less ▲]

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See detailAn experimental and numerical analysis of the influence of the inlet temperature, equivalence ratio and compression ratio on the HCCI auto-ignition process of Primary Reference Fuels in an engine
Machrafi, Hatim ULg; Cavadias

in Fuel Processing Technology (2008), 89(11), 1218-1226

In order to understand better the auto-ignition process in an HCCI engine, the influence of some important parameters on the auto-ignition is investigated. The inlet temperature, the equivalence ratio and ... [more ▼]

In order to understand better the auto-ignition process in an HCCI engine, the influence of some important parameters on the auto-ignition is investigated. The inlet temperature, the equivalence ratio and the compression ratio were varied and their influence on the pressure, the heat release and the ignition delays were measured, The inlet temperature was changed from 25 to 70 degrees C and the equivalence ratio from 0.18 to 0.41, while the compression ratio varied from 6 to 13.5. The fuels that were investigated were PRF40 and n-heptane. These three parameters appeared to decrease the ignition delays, with the inlet temperature having the least influence and the compression ratio the most. A previously experimentally validated reduced surrogate mechanism, for mixtures of n-heptane, iso-octane and toluene, has been used to explain observations of the auto-ignition process. The same kinetic mechanism is used to better understand the underlying chemical and physical phenomena that make the influence of a certain parameter change according to the operating conditions. This can be useful for the control of the auto-ignition process in an HCCI engine. (C) 2008 Elsevier B.V. All rights reserved. [less ▲]

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See detailExperimental and Numerical Approaches of Contact with Friction and Wear in Large Deformation
Cescotto, Serge ULg; Charlier, Robert ULg; Bricout, J. P. et al

in European Journal of Mechanical Engineering (1991), 36(n° 2),

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See detailExperimental and Numerical Characterization of Damage and Application to Incremental Forming
Guzmán Inostroza, Carlos Felipe ULg

Doctoral thesis (2016)

Nowadays, product manufacturing can be divided into two groups: relatively simple products produced in a large production chain and complex (specialized) components produced in reduced batches. Within the ... [more ▼]

Nowadays, product manufacturing can be divided into two groups: relatively simple products produced in a large production chain and complex (specialized) components produced in reduced batches. Within the second group, prototyping through incremental sheet forming (ISF) has been subject of several studies. ISF refers to processes where the plastic deformation occurs by repeated contact with a relatively small tool. A crucial aspect in the ISF processes is that the final shape is determined only by the tool movement. The focus of this research is the single point incremental forming (SPIF) process variant, where a clamped sheet metal is deformed by using a relatively small spherical tool. SPIF has several advantages over traditional forming, such as the high formability attainable by the material. Different hypothesis haven been proposed to explain this behavior, but there is still not a clear and definitive understanding of the relation between the particular stress and strain state induced in the material during SPIF and the material degradation leading to localization or fracture. In this thesis, a fundamental research is proposed using the finite element (FE) code LAGAMINE, developed within the University of Liège. Numerical implementation and validation of the Gurson-Tvergaard-Needleman (GTN) damage model into this FE code is performed. An experimental test campaign is developed to characterize plastic and damage behavior and to validate the damage model for the DC01 steel grade. Finally, this damage model is applied to simulate the SPIF process in order to verify if it is capable to predict failure. The thesis discusses the material parameter identification for classical plasticity models, describing the anisotropy and hardening behavior of the sheet metal. The derivation of the equations of the numerical damage model and the efficiency of the implementation is presented in great detail. A methodology for the numerical parameter identification of the damage model is proposed, including microscopic measurements by optical microscopy and strain and displacement field measurements by digital image correlation (DIC). The identified Gurson model is applied to simulate standard SPIF geometries, like the line, cone and pyramid tests. The simulations are performed using the solid-shell element formulation and validated in terms of shape and force prediction. Literature reviews of the Gurson model and the SPIF process are also included. The experimental results show that the selected material (DC01 steel sheet) exhibits a slight anisotropic behavior and work-hardening stagnation on cyclic tests. The performed microscopic measurements are not representative of the actual damage, but they give a qualitative estimation of the physical mechanism of fracture. The initial porosity of the material was determined using optical microscopy measurements in the base material. The numerical implementation of the model is developed with all variables integrated in an implicit way, based on the backward Euler scheme. Nucleation, coalescence and shear extensions implementations are validated by results obtained from the literature. The macroscopic campaign allowed to identify the parameters for nucleation, coalescence and shear. An unique set of results matching all experiments was not possible to obtain, so different sets of parameters are retrieved following an approach that includes inverse modeling and sensitivity analysis. A numerical-experimental comparison of strain values in the loading direction shows that the model is able to correctly predict the strain distribution except during localization of the strain. Globally, the obtained set of material parameters is in good agreement with the experimental results. For SPIF FE simulations, the results of the shape prediction are in good agreement with the experimental results, both for the line and pyramid test. Nevertheless, the force prediction is too high compared to reference values. On the other hand, the GTN model is capable to detect failure in a pyramid and a cone, but the prediction is too premature compared to the experimental failure angle for the same material and geometry. An accurate prediction of failure for the SPIF process was not possible to achieve. The GTN model extended to shear presents inherent flaws that prevent an accurate prediction of the failure angle for the SPIF process. Hence, an extensive research on the damage mechanisms leading to fracture for SPIF cannot rely (only) on the GTN model. The classical coalescence model of the GTN model is insufficient to correctly predict failure. Hence, it is recommended that further analysis concentrates on the description of this particular stage of damage evolution. During the development of this thesis, a robust implementation of the GTN model into the FE code LAGAMINE was done, including an extensive experimental database of microscopic and macroscopic measurements for the DC01 steel sheet. Other phenomena can be explored thanks to this model. [less ▲]

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