Haifa Sallem

HES-SO University of Applied Sciences and Arts Western Switzerland · Institut Systèmes industriels

This study provides a comprehensive benchmark comparison of microstructure, mechanical properties, and their evolution during subsequent heat treatment of 17-4PH Martensitic stainless steel (MSS) processed by laser powder bed fusion (LPBF) and its commercially rolled counterparts. The results reveal that LPBF samples exhibit a finer martensitic mic...

This research is devoted to forecast the distortion of aileron brackets by means of generative design (GD) and multi-scaled numerical simulation comprising meso- and macro-scaled simulation based on thermomechanical method (TMM) and inherent strain method (ISM), respectively. The multi-scaled simulation began with TMM-based virtual calibration test...

Nitinol alloys stents have been printed by Selective Laser Melting from a gas atomized powder with a composition of 50.8 at% Ni. The energy density has been adapted to set the austenite finish temperature just below the human body temperature, therefore the stent diameter can be reduced by plastic strain at lower temperature and recover its former...

For cyclic loading applications and critical structural, the emergence of flaws in additively manufactured components is a key concern. This study highlighted the defects generated by selective laser melting (SLM) to the 17-4 PH stainless steel parts. The defects were quantified using an experimental study: Optical microscope and roughness meter to...

The effects of the thermal post-treatments on the mechanical properties of SLMed 17-4PH stainless steel are studied. Three thermal post-treatments are carried out: (E0) as received state, (E1 and E2) solution annealing treatment and (E3) aging treatment. Microhardness, impact-strength, and wear tests are carried out to determine the effect of treat...

Metal laser powder bed fusion (L-BPF) technology is one of the most common and evolved additive manufacturing technologies to fabricate metal components. However, the control of defects generated during the SLM process remains an essential technological challenge for its implementation in production lines. In this work, based on the combination of...

Additive Manufacturing (AM) using Selective Laser Melting (SLM) has gained significant prominence across various industries involved in stainless steel part manufacturing. Selective Laser Melting makes it possible to manufacture parts with very complex geometry and with remarkable mechanical and physicochemical properties by controlling the microst...

The objectives of this project are to design and manufacture, using 3D printing, a highly energy-efficient multi-channel hydrogen heat exchanger that will both improve the efficiency of the energy conversion chain in the fuel cells and high-temperature electrolysis (SOFC / SOEC) developed by Celectis Sàrl, and recover the excess heat emitted by the...

The main goal of this attempt is to explore and analyze the behavior of a material containing artificial surface defect and solicited under variable amplitude cyclic loading. The observation and the follow-up of the loading history and the characterization of the damage accumulation were evaluated in the presence of an artificial surface defect. Th...

Nowadays, one of the biggest challenges for manufacturers, especially in aerospace industry, is to achieve dimensional accuracy and ensure mechanical parts quality while optimizing the production lines. Consequently, the control of stresses and distortions, arising from mechanical loads and heat effects during successive manufacturing processes, is...

This article presents a fatigue damage cumulative model under variable loading devoted for defective materials. The multiaxial stress amplitude is reported to the equivalent stress by combining it with the S–N curve and an algorithm to evaluate the damage model. The proposed model is connected cycle by cycle with the Wöhler curve and it takes into...

L’objectif de cette étude est de montrer numériquement, les effets des écoulements fluides dans le bain fondu, sur la distribution des phases et des contraintes résiduelles générées. Deux approches numériques sont adoptées. Dans la première, une simulation thermo-fluide est réalisée prenant en compte la tension de surface « effet Marangoni » et la...

L’objectif de ce travail est de montrer numériquement, au cours du procédé de soudage, l’influence des écoulements de la matière dans le bain fondu sur l’évolution des contraintes résiduelles générées. Ainsi deux approches numériques différentes sont adoptées afin d’assurer le couplage des différents états de la matière liquide et solide, y compris...

La simulation numérique du soudage est un sujet d'intérêt croissant depuis une bonne trentaine d'années. D'abord destinés à prédire les contraintes résiduelles générées par une opération de soudage conventionnel, les travaux de recherche se sont peu à peu orientés vers la simulation des distorsions, une meilleure maitrise du bain fondu, du procédé...

The aim of this work is to present and compare two numerical modeling approaches for the simulation of residual stresses caused by the welding process. In the first approach, the coupling of the different material states is ensured using an ALE method. The molten pool and the fluid flows are modeled. However in the second approach, numerical simula...

The purpose of the present paper is to improve the description of residual stress field characteristics generated after welding. The behavior of the material both in the liquid and solid states and during all heating and cooling stages including the solidification in the mushy zone is considered, as well as the surface tension effects in the liquid...

Inducing complex thermo-mechanical loads during grinding process of hard materials, such as high alloyed high speed steel, may affect the surface integrity and thus the performance of engineering parts. Residual stresses are considered as the most significant parameter which allows a good assessment of the performance of ground part. Earlier studie...

Le but de cet article est de montrer la pertinence de l’élément fini P1/P1 pour l’analyse mécanique des métaux solides présentant un comportement élasto-viscoplastique. Une simulation représentative d’un cas de soudage est traitée. Les résultats obtenus se comparent favorablement à ceux obtenus avec un maillage de référence utilisant des éléments h...

Fusion welding process induces high residual stresses in the final welded components which may strongly affect their in-service behaviour in term of fatigue and corrosion. Numerical simulation is a good tool widely used for structural integrity assessment of structures containing welds. Based on coupled thermal and mechanical finite element analysi...

This paper deals with the influence of both defect and loading sequence on fatigue damage accumulation of C35 steel containing artificial defects. Tests were carried out using fatigue samples with artificial spherical defects introduced at the surface. Tests were performed using two blocks loading under increasing and decreasing magnitude. The expe...

La qualité des tôles laminées dépend de la qualité microgéométrique du cylindre de laminage. Celle-cià son tour dépend du procédé de rectification qui a permis la réalisation de la surface fonctionnelle. Enfin, la durée de vie des cylindres dépend de l'intégrité de surface à savoir la topographie de surface, la microstructure de la zone affectée, l...

Grinding is one of the important metal cutting processes used extensively in the finishing operation to get components of desired shape, size and accuracy. A perfect control of this process is thus necessary to ensure correct final part and limit damage. Lifetime of machined part depends on the surface integrity especially in terms of microstructur...

Grinding process is an energy intensive process in the sense that, it requires a larger amount of energy per unit of volume of material removal compared to other metal cutting processes. In this case, effects on the ground workpiece in terms of induced residual stresses and metallurgical changes due to heat generated play an important role on the l...

L’objectif de ce travail est d’explorer et d’analyser le comportement d’un matériau présentant un défaut vis-à-vis à un chargement cyclique à amplitude variable. L’observation et le suivi de l’histoire du chargement et la caractérisation du cumul d’endommagement ont été analysés en présence d’un défaut surfacique artificiel. Le choix des deux nivea...