https://sam.ensam.eu:443 The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material. Tue, 09 Jun 2026 18:58:37 GMT 2026-06-09T18:58:37Z http://hdl.handle.net/10985/25745 Identification of friction coefficient between uncoated carbide tool and Ti-6Al-4V alloy under different lubrication conditions FERSI, Achraf; YESSINE, AYED; LAVISSE, BRUNO; GERMAIN, Guenael During machining, the friction between the tool and the workpiece (cutting face and flank face) is a significant tribological phenomenon because it strongly influences the cutting operation. Indeed, higher friction leads to an increase of cutting forces, a greater heat generation, a premature tool wear and a surface degradation. This study focuses on tool (WC/Co)/workpiece (Ti-6Al-4V) friction under different cooling conditions (dry, emulsion, cryogenic). Determining the friction coefficient requires numerical simulations to separate the tribological phenomena. For this purpose, several modeling methods are compared (Lagrangian, CEL, and ALE). Experimental tests revealed that the friction coefficient depends not only on the sliding velocity but also on lubrication modes. Specifically, the lowest friction coefficient is obtained under cryogenic condition. Adhesive phenomena on the WC/Co pin are observed in the friction zone, particularly at high sliding velocities. Wed, 15 May 2024 00:00:00 GMT http://hdl.handle.net/10985/25745 2024-05-15T00:00:00Z FERSI, Achraf YESSINE, AYED LAVISSE, BRUNO GERMAIN, Guenael During machining, the friction between the tool and the workpiece (cutting face and flank face) is a significant tribological phenomenon because it strongly influences the cutting operation. Indeed, higher friction leads to an increase of cutting forces, a greater heat generation, a premature tool wear and a surface degradation. This study focuses on tool (WC/Co)/workpiece (Ti-6Al-4V) friction under different cooling conditions (dry, emulsion, cryogenic). Determining the friction coefficient requires numerical simulations to separate the tribological phenomena. For this purpose, several modeling methods are compared (Lagrangian, CEL, and ALE). Experimental tests revealed that the friction coefficient depends not only on the sliding velocity but also on lubrication modes. Specifically, the lowest friction coefficient is obtained under cryogenic condition. Adhesive phenomena on the WC/Co pin are observed in the friction zone, particularly at high sliding velocities. http://hdl.handle.net/10985/25746 Estimation of the residual stress field of laminated aeronautical parts to prevent distortion after machining CHAABANI, Khayel; BEN SAADA, Mariem; LAVISSE, BRUNO; RITOU, Mathieu; GERMAIN, Guenael The estimation of post-machining distortion of monolithic aeronautical parts induced by the redistribution of the bulk residual stresses (RS) during machining is one of the major challenges of aeronautical parts manufacturing. Since it is the main cause of thick parts post-machining distortion, it is essential to know the state of the initial RS so that the machining strategy can be modified to minimize distortion of each part. The problem is even more complex because the RS field is not identical from one part to another. Considering an average stress field provides satisfactory results only for parts with simple geometries and a highly repeatable manufacturing process, which is rarely the case in an industrial setting. By simulating the steps of the production of the laminated blank, the variability of RS field will be established. This variability can be used to determine the distribution of the RS field of each part during machining. Wed, 15 May 2024 00:00:00 GMT http://hdl.handle.net/10985/25746 2024-05-15T00:00:00Z CHAABANI, Khayel BEN SAADA, Mariem LAVISSE, BRUNO RITOU, Mathieu GERMAIN, Guenael The estimation of post-machining distortion of monolithic aeronautical parts induced by the redistribution of the bulk residual stresses (RS) during machining is one of the major challenges of aeronautical parts manufacturing. Since it is the main cause of thick parts post-machining distortion, it is essential to know the state of the initial RS so that the machining strategy can be modified to minimize distortion of each part. The problem is even more complex because the RS field is not identical from one part to another. Considering an average stress field provides satisfactory results only for parts with simple geometries and a highly repeatable manufacturing process, which is rarely the case in an industrial setting. By simulating the steps of the production of the laminated blank, the variability of RS field will be established. This variability can be used to determine the distribution of the RS field of each part during machining. http://hdl.handle.net/10985/26323 Recent advances in the remelting process for recycling aluminium alloy chips: a critical review CHEN, Xin; BEN SAADA, Mariem; LAVISSE, BRUNO; AMMAR, Amine This critical review examines advances in preprocessing and remelting processes for aluminium alloy chip recycling, emphasizing pre-treatment and remelting techniques that improve both resource recovery and material quality. Pre-treatment strategies, particularly cleaning methods and compaction are critically evaluated. Various cleaning methods, including centrifugation, ultrasonic solvent washing, extraction, and distillation are compared based on their ability to remove residual cutting fluids. Cold compaction, which augments chip density to approximately 2.5 g/cm³, significantly curtails oxidation losses and enhances metal recovery. During remelting, NaCl-KCl-based fluxes with limited fluoride additions (e.g., 3–7 wt% Na₃AlF₆) disrupt oxide networks but require careful dosage control to minimize furnace corrosion and environmental hazards. Moreover, mechanical stirring combined with suitable melting temperatures reduces porosity while enhancing melt purity. Future research should prioritize the development of low-energy cleaning methods, flux composition optimization, and scalable production techniques to further advance sustainable aluminium recycling. Thu, 24 Apr 2025 00:00:00 GMT http://hdl.handle.net/10985/26323 2025-04-24T00:00:00Z CHEN, Xin BEN SAADA, Mariem LAVISSE, BRUNO AMMAR, Amine This critical review examines advances in preprocessing and remelting processes for aluminium alloy chip recycling, emphasizing pre-treatment and remelting techniques that improve both resource recovery and material quality. Pre-treatment strategies, particularly cleaning methods and compaction are critically evaluated. Various cleaning methods, including centrifugation, ultrasonic solvent washing, extraction, and distillation are compared based on their ability to remove residual cutting fluids. Cold compaction, which augments chip density to approximately 2.5 g/cm³, significantly curtails oxidation losses and enhances metal recovery. During remelting, NaCl-KCl-based fluxes with limited fluoride additions (e.g., 3–7 wt% Na₃AlF₆) disrupt oxide networks but require careful dosage control to minimize furnace corrosion and environmental hazards. Moreover, mechanical stirring combined with suitable melting temperatures reduces porosity while enhancing melt purity. Future research should prioritize the development of low-energy cleaning methods, flux composition optimization, and scalable production techniques to further advance sustainable aluminium recycling. http://hdl.handle.net/10985/22983 Investigations of grinding burn on a nitrided steel LAVISSE, Bruno; WEISS, Laurent; KOKANYAN, Ninel; LEFEBVRE, André; HENRION, Emerik; SINOT, Olivier; TIDU, Albert Grinding process may lead to the occurrence of grinding burn. When the temperature in the contact zone gets too high, it may lead to damage of the workpiece. The target of this study was to characterize changes occurring in the material after grinding burn on a nitrided steel. The microstructural changes after burn were quantified, by using residual stresses, Raman spectroscopy was also use to detect and characterize different oxides, appearing after grinding burn. The study highlights the possibilities of using this last non destructive method for detecting and quantifying grinding burn. Wed, 01 Jun 2022 00:00:00 GMT http://hdl.handle.net/10985/22983 2022-06-01T00:00:00Z LAVISSE, Bruno WEISS, Laurent KOKANYAN, Ninel LEFEBVRE, André HENRION, Emerik SINOT, Olivier TIDU, Albert Grinding process may lead to the occurrence of grinding burn. When the temperature in the contact zone gets too high, it may lead to damage of the workpiece. The target of this study was to characterize changes occurring in the material after grinding burn on a nitrided steel. The microstructural changes after burn were quantified, by using residual stresses, Raman spectroscopy was also use to detect and characterize different oxides, appearing after grinding burn. The study highlights the possibilities of using this last non destructive method for detecting and quantifying grinding burn. http://hdl.handle.net/10985/27044 Effect of different cryogenic lubrication methods on machinability of Ti6Al4V DE PAIVA SILVA, Gabriel; AYED, Yessine; LAVISSE, Bruno; GERMAIN, Guenael Abstract. In machining industry, there is a growing interest in cryogenic cooling techniques, because of their environmental benefits, including reduced toxicity, safer operation, and lower environmental impact compared to conventional cutting fluids. The titanium alloy Ti6Al4V, which is commonly used in aerospace, automotive and biomedical industries, presents low machinability and often requires abundant use of cutting fluids to inhibit tool wear. This study investigates the machinability of Ti6Al4V, comparing conventional lubrication (water-oil emulsion) with two cryogenic fluids: liquid nitrogen (LN2) and liquid carbon dioxide (LCO2). Longitudinal turning tests were conducted and tool life, wear mechanisms, and cutting forces were evaluated for each lubrication condition. The tool life provided by emulsion, LN2 and Vc were 8.2 min, 17.7 min and 9.9 min, respectively. Adhesion was identified as the predominant wear mechanism across all conditions. Overall, the results suggest that the cryogenic coolants can effectively increase tool life and reduce cutting forces in comparison with conventional lubrication, however, further optimizations of the delivery system of the cryogenic coolants are still necessary. Wed, 07 May 2025 00:00:00 GMT http://hdl.handle.net/10985/27044 2025-05-07T00:00:00Z DE PAIVA SILVA, Gabriel AYED, Yessine LAVISSE, Bruno GERMAIN, Guenael Abstract. In machining industry, there is a growing interest in cryogenic cooling techniques, because of their environmental benefits, including reduced toxicity, safer operation, and lower environmental impact compared to conventional cutting fluids. The titanium alloy Ti6Al4V, which is commonly used in aerospace, automotive and biomedical industries, presents low machinability and often requires abundant use of cutting fluids to inhibit tool wear. This study investigates the machinability of Ti6Al4V, comparing conventional lubrication (water-oil emulsion) with two cryogenic fluids: liquid nitrogen (LN2) and liquid carbon dioxide (LCO2). Longitudinal turning tests were conducted and tool life, wear mechanisms, and cutting forces were evaluated for each lubrication condition. The tool life provided by emulsion, LN2 and Vc were 8.2 min, 17.7 min and 9.9 min, respectively. Adhesion was identified as the predominant wear mechanism across all conditions. Overall, the results suggest that the cryogenic coolants can effectively increase tool life and reduce cutting forces in comparison with conventional lubrication, however, further optimizations of the delivery system of the cryogenic coolants are still necessary. http://hdl.handle.net/10985/27043 Cryogenic effects on the mechanical behavior of bulk metallic glasses MANGOURNY, Laura; LAVISSE, Bruno; AYED, Yessine; GERMAIN, Guenael Abstract. Bulk metallic glasses (BMGs), unlike crystalline alloys, exhibit significantly enhanced plastic deformation when tested at cryogenic temperatures. This enhanced plasticity is primarily characterized by the slowed propagation of shear bands and the formation of multiple shear bands, which play a crucial role in the material's behavior at low temperatures. Due to their amorphous nature, BMGs are prone to catastrophic fractures once shear band nucleation and propagation occur, a behavior distinct from that of crystalline materials. However, the underlying mechanisms of BMG failure and the effect of strain rate remain controversial. This study investigates the mechanical behavior of a Zr-based BMG under cryogenic conditions. Compression tests were conducted at room temperature and -180°C, using liquid nitrogen, across a range of strain rates. The results show that, at cryogenic temperatures, ductility increases, though it remains relatively low, leaving uncertain its impact on machinability. Notably, larger stress drops were observed at ambient temperature, likely linked to shear band formation. Additionally, the study identified two distinct fracture modes during dynamic tests, warranting further investigation. This research provides valuable insights into the behavior of BMGs under cryogenic conditions and their machinability. Wed, 07 May 2025 00:00:00 GMT http://hdl.handle.net/10985/27043 2025-05-07T00:00:00Z MANGOURNY, Laura LAVISSE, Bruno AYED, Yessine GERMAIN, Guenael Abstract. Bulk metallic glasses (BMGs), unlike crystalline alloys, exhibit significantly enhanced plastic deformation when tested at cryogenic temperatures. This enhanced plasticity is primarily characterized by the slowed propagation of shear bands and the formation of multiple shear bands, which play a crucial role in the material's behavior at low temperatures. Due to their amorphous nature, BMGs are prone to catastrophic fractures once shear band nucleation and propagation occur, a behavior distinct from that of crystalline materials. However, the underlying mechanisms of BMG failure and the effect of strain rate remain controversial. This study investigates the mechanical behavior of a Zr-based BMG under cryogenic conditions. Compression tests were conducted at room temperature and -180°C, using liquid nitrogen, across a range of strain rates. The results show that, at cryogenic temperatures, ductility increases, though it remains relatively low, leaving uncertain its impact on machinability. Notably, larger stress drops were observed at ambient temperature, likely linked to shear band formation. Additionally, the study identified two distinct fracture modes during dynamic tests, warranting further investigation. This research provides valuable insights into the behavior of BMGs under cryogenic conditions and their machinability. http://hdl.handle.net/10985/25704 Machining assistance techniques: impact on tool wear and surface integrity on aeronautic alloys GERMAIN, Guenael; AYED, Yessine; LAVISSE, Bruno; CADOUX, Tanguy This article discusses the effect of machining assistance on the machinability and surface integrity of titanium and nickel-based alloys for turning operations. The presented results are based on a literature review of the principal experimental work published by the French research laboratories within the framework of the Manufacturing 21 group. The work presented focuses on the assistances the most studied by the research group: cryogenic assistance and high-pressure assistance. This paper specifically addresses the experimental approaches used to determine the effect of the assistant on the cutting force, tool wear, chip formation, microstructural changes, and residual stresses generated on the workpiece machined surface. This literature review is completed by new results comparing machining tests on the Ti6Al4V titanium alloy using high pressure and cryogenic assistances. The results show that the assistances increase the tool life, as well as improve the surface integrity of the parts. However, these gains are not identical from one material to another. In particular, titanium alloys and nickel alloys show how a very different gains for a fixed assistance. The conclusions presented highlight current trends and research needs. Mon, 24 Apr 2023 00:00:00 GMT http://hdl.handle.net/10985/25704 2023-04-24T00:00:00Z GERMAIN, Guenael AYED, Yessine LAVISSE, Bruno CADOUX, Tanguy This article discusses the effect of machining assistance on the machinability and surface integrity of titanium and nickel-based alloys for turning operations. The presented results are based on a literature review of the principal experimental work published by the French research laboratories within the framework of the Manufacturing 21 group. The work presented focuses on the assistances the most studied by the research group: cryogenic assistance and high-pressure assistance. This paper specifically addresses the experimental approaches used to determine the effect of the assistant on the cutting force, tool wear, chip formation, microstructural changes, and residual stresses generated on the workpiece machined surface. This literature review is completed by new results comparing machining tests on the Ti6Al4V titanium alloy using high pressure and cryogenic assistances. The results show that the assistances increase the tool life, as well as improve the surface integrity of the parts. However, these gains are not identical from one material to another. In particular, titanium alloys and nickel alloys show how a very different gains for a fixed assistance. The conclusions presented highlight current trends and research needs. http://hdl.handle.net/10985/25705 Characterization of friction behavior under cryogenic conditions: Ti–6Al–4V FERSI, Achraf; AYED, Yessine; LAVISSE, BRUNO; GERMAIN, Guenael Friction phenomena at the chip/tool/workpiece interfaces during machining of material impacts significantly the cutting process. In this article, the effect of friction conditions (dry, emulsion, cryogenic) on the tribological performance of uncoated tungsten carbide tools is investigated when machining titanium alloy Ti–6Al–4V. Friction tests were conducted to analyze the impact of sliding speed and cooling on the evolution of the friction coefficient. To determine the real friction coefficient (adhesive friction coefficient), a numerical simulation using the Lagrangian method was employed. After a comparative study of various simulation methods (“Lagrangian”, “CEL”, and “ALE”), the Lagrangian method was identified as the most relevant. The obtained results reveal that an increase of sliding velocity significantly influences the friction coefficient. Additionally, the application of cryogenic fluid (LN2) reduces the friction coefficient compared to both dry and emulsion-based friction. Adhesion phenomena play a crucial role in the nature of the contact, especially at high sliding velocities. Fri, 22 Mar 2024 00:00:00 GMT http://hdl.handle.net/10985/25705 2024-03-22T00:00:00Z FERSI, Achraf AYED, Yessine LAVISSE, BRUNO GERMAIN, Guenael Friction phenomena at the chip/tool/workpiece interfaces during machining of material impacts significantly the cutting process. In this article, the effect of friction conditions (dry, emulsion, cryogenic) on the tribological performance of uncoated tungsten carbide tools is investigated when machining titanium alloy Ti–6Al–4V. Friction tests were conducted to analyze the impact of sliding speed and cooling on the evolution of the friction coefficient. To determine the real friction coefficient (adhesive friction coefficient), a numerical simulation using the Lagrangian method was employed. After a comparative study of various simulation methods (“Lagrangian”, “CEL”, and “ALE”), the Lagrangian method was identified as the most relevant. The obtained results reveal that an increase of sliding velocity significantly influences the friction coefficient. Additionally, the application of cryogenic fluid (LN2) reduces the friction coefficient compared to both dry and emulsion-based friction. Adhesion phenomena play a crucial role in the nature of the contact, especially at high sliding velocities. http://hdl.handle.net/10985/25744 Numerical investigation and modeling of residual stress field variability impacting the machining deformations of forged part CHABEAUTI, Hugo; RITOU, Mathieu; LAVISSE, BRUNO; GERMAIN, Guenael; CHARBONNIER, Virginie Aluminum alloys are widely used for structural parts in the aerospace industry. Those parts are usually machined from rolled plates or forged blanks, and heat treatments are carried out to reach the necessary mechanical properties. Forming and heat treatments induce residual stresses that generate deformations during and after machining because material removal modifies their balance. One major issue in industry is the important variability of the residual stress field in forged blanks. A better knowledge of the residual stress field will enable the definition of better machining strategy to minimize the deformations. In order to understand and manage this variability, a sensibility analysis was performed to investigate the impact of their different potential sources. It relies on a coupling of 2D-FEM and beam model simulations. Then, this work introduces a model reduction technique (by POD and SVD) to build a model of the variability of a stress field and shows how it could be used on the production line. Sat, 01 Jan 2022 00:00:00 GMT http://hdl.handle.net/10985/25744 2022-01-01T00:00:00Z CHABEAUTI, Hugo RITOU, Mathieu LAVISSE, BRUNO GERMAIN, Guenael CHARBONNIER, Virginie Aluminum alloys are widely used for structural parts in the aerospace industry. Those parts are usually machined from rolled plates or forged blanks, and heat treatments are carried out to reach the necessary mechanical properties. Forming and heat treatments induce residual stresses that generate deformations during and after machining because material removal modifies their balance. One major issue in industry is the important variability of the residual stress field in forged blanks. A better knowledge of the residual stress field will enable the definition of better machining strategy to minimize the deformations. In order to understand and manage this variability, a sensibility analysis was performed to investigate the impact of their different potential sources. It relies on a coupling of 2D-FEM and beam model simulations. Then, this work introduces a model reduction technique (by POD and SVD) to build a model of the variability of a stress field and shows how it could be used on the production line. http://hdl.handle.net/10985/24204 Digital twin of forged part to reduce distortion in machining CHABEAUTI, Hugo; RITOU, Mathieu; LAVISSE, BRUNO; GERMAIN, Guénaël; CHARBONNIER, Virginie When long parts are machined in forged blanks, the variability of bulk residual stress (RS) fields leads to uncontrolled deformation after machining, requiring manual reshaping. An original hybrid digital twin of forged part is thus proposed to manage the bulk RS variability and reduce part distortion in machining. The behavior model of parts relies both on reduced models of thermomechanical simulations of the forging pro-cess variability, on-line measurements and machine learning from the previous parts deformations. Adaptive machining solutions can then be simulated for a rapid decision-making. The approach was validated on a series of aeronautic forged parts. Tue, 18 Apr 2023 00:00:00 GMT http://hdl.handle.net/10985/24204 2023-04-18T00:00:00Z CHABEAUTI, Hugo RITOU, Mathieu LAVISSE, BRUNO GERMAIN, Guénaël CHARBONNIER, Virginie When long parts are machined in forged blanks, the variability of bulk residual stress (RS) fields leads to uncontrolled deformation after machining, requiring manual reshaping. An original hybrid digital twin of forged part is thus proposed to manage the bulk RS variability and reduce part distortion in machining. The behavior model of parts relies both on reduced models of thermomechanical simulations of the forging pro-cess variability, on-line measurements and machine learning from the previous parts deformations. Adaptive machining solutions can then be simulated for a rapid decision-making. The approach was validated on a series of aeronautic forged parts.