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Coupled Eulerian-Lagrangian (CEL) simulation for modelling of chip formation in AA2024-T3

Procedia CIRP 2019年 82卷 142-147页

作者： F. Ducobu E. Rivière-Lorphèvre M. Galindo-Fernandez S. Ayvar-Soberanis P.-J. Arrazola H. Ghadbeigi University of Mons (UMONS) Faculty of Engineering (FPMs) Machine Design and Production Engineering Lab 20 Place du Parc B-7000 Mons Belgium Department of Mechanical Engineering The University of Sheffield Mappin Street Sheffield S1 3JD UK Advanced Manufacturing Research Centre The University of Sheffield Advanced Manufacturing park Catcliffe Rotherham S60 5TZ UK Mondragon University Faculty of Engineering Mechanical and Manufacturing Department Mondragón 20500 Spain

Aluminium alloys are of the most used alloys in the aeronautic industry. Increasing knowledge in machining and prediction of chip formation in these materials is crucially important to design better components with enhanced functional performance. To achieve this, a new finite element modelling strategy is developed to incorporate material damage and softening in the Coupled Eulerian-Lagrangian (CEL) formulation for the machining of AA2024 alloy. The CEL modelling technique is adopted to simulate chip formation at high cutting speeds. An orthogonal cutting setup is used to compare the modelling predictions with experimentally measured cutting forces and chips sections. The proposed model shows a good ability to reproduce the experimental results and to predict the trends induced by variations in the cutting conditions.

关键词： Finite element method (FEM) Machining Aluminium

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Chemical etching as a finishing process for electron beam melting (EBM) parts

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AIP Conference Proceedings 2019年第1期2113卷

作者： Adrien Dolimont Anthonin Demarbaix François Ducobu Edouard Rivière-Lorphèvre 1Corresponding author : Machine Design and Production Engineering Lab - Faculty of Engineering - University of Mons Place du parc 20 7000 Mons Belgium

Additive Manufacturing (AM) allows to reduce the industrialization step by eliminating or minimizing the tools conception phase, process development,… These technologies permit now to produce real parts with required mechanical properties. AM technologies allow new ways of thinking by unlocking the design limitations encountered by other manufacturing methods. The Electron Beam Melting (EBM) technology is a powder-bed-metal based additive manufacturing technique developed at Chalmers University of technology in the late 1990’s and commercialized by the Swedish company ARCAM AB in the early 2000’s. The most widely used material for the EBM Process is Ti6Al4V. This is the material used in this study with standard processing parameters. EBM process is a near net shape process and it is necessary to carry out finishing operation after EBM. The goal of this research is to analyze the impact of chemical etching on parts produced by electron beam melting. Given that the surface conditions are poor (Ra between 25 to 35 µm), an enhancement of these is asked. Dimensional and surface measurements were realized on conceived parts. Different exposure times were tested. The impact of these times on surface quality was evaluated. To help predicting the excess thickness to be provided, the dimensional impact of chemical polishing on EBM parts was estimated. 36 parts were measured before and after chemical machining. The improvement of surface quality was also evaluated after each treatment.

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Comparison of Johnson-Cook and modified Johnson-Cook material constitutive models and their influence on finite element modelling of Ti6Al4V orthogonal cutting process

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AIP Conference Proceedings 2019年第1期2113卷

作者： Nithyaraaj Kugalur-Palanisamy Edouard Riviere-Lorphèvre Pedro-José Arrazola François Ducobu 1University of Mons Faculty of Engineering Machine Design and Production Engineering Lab - Belgium 2Mondragon University Faculty of Engineering Mechanical and Manufacturing Department - Spain

Titanium alloys such as Ti6Al4V are widely used and are well known as hard-to-machine material. The material behavior that is described by the constitutive equation plays a pivotal role in modeling and simulation of machining process. The Johnson–Cook material model is widely used for analysis of material flow stress, especially for those materials with a flow stress highly influenced by high values of temperature and strain rate. A continuous improvement on constitutive models for accurate prediction of the work material behavior under machining conditions is observed in the literature. The purpose of this study is to show the influence of the constitutive model by comparing and investigating Johnson-Cook constitutive model with calibrated or modified Johnson-Cook constitutive models that take into account temperature dependent hardening factor and its coupled effects between strain and temperature. This paper deals with the simulation of orthogonal cutting process with those constitutive models. The three constitutive models are included in a Lagrangian cutting finite element model to highlight their influence on the results. Cutting forces and chip morphology are mainly used in the comparison of the numerical results and their validation with an experimental reference.

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The hybrid machining of ceramic: The choice of production stage 17

The hybrid machining of ceramic: The choice of production st...

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17th International Conference of the European Society for Precision engineering and Nanotechnology, EUSPEN 2017

作者： Demarbaix, A. Rivière-Lorphèvre, E. Ducobu, F. Filippi, E. Petit, F. University of Mons Faculty of Engineering Machine Design and Production Engineering Lab. Place du Parc 20 Mons7000 Belgium Research and Technological Support Department BCRC-INISMa Av. Gouverneur Cornez 4 Mons7000 Belgium

ISBN: (纸本)9780995775107

The demand for micro products has increased gradually since last decades in various areas, requiring the development of micro manufacturing processes. Micro manufacturing is characterized by the size of functional features (smaller than 10 um), a high precision, a good surface finishing and complex parts in a wide variety of materials. The Traditional Machining Processes (TMPs) are intensively used to produce micro-components, but the minimum feature size they can produce is limited. In parallel, the Nontraditional Machining Processes (NMPs) were developed to manufacture micro components of a few microns, but the processing times are slower. Hybrid Machining Processes (HMPs) was introduced to address the demand to increase production with an enhanced quality for difficult-to-machine materials such as ceramics. In this paper, the HMP considered, a combination of micro-milling and laser machining, is developed to machine ceramic materials. This HMP may be carried out at different stages in the ceramic production. The goal of this paper is to determine the most attractive production stage in ceramic machining with this HMP.

关键词： Milling (machining)

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Performance simulation of different toolpaths in 2D1/2 pocket milling

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AIP Conference Proceedings 2019年第1期2113卷

作者： Cédric Leroy Edouard Rivière-Lorphèvre Francois Ducobu Sylvain Lavernhe Christoph Tournier Enrico Filippi 1Machine Design and Production Lab – Faculty of Engineering – UMONS Place du Parc 20 – B-7000 MONS – BELGIUM 2LURPA – ENS de CACHAN – avenue du Président Wilson 61 – 94235 CACHAN France

Pocket milling is a common task in manufacturing of aeronautical or space use parts, but also for molds and dies. This process is time-consuming and has an important impact on the cost of the final *** this paper, among all the possible directions of 2D1/2 pocketing improvement, the optimization of toolpath geometry has been chosen. Most of time, the toolpaths are computed from a Computer Aided Manufacturing software using classical tool trajectories such as “zig-zag” or “contour parallel”. These trajectories show discontinuities or local high curvature, creating frequent stop and go of the tool. These toolpaths are, fundamentally, not efficient in High Speed Milling. Some authors and software designers proposed methods to tackle those problems by local modification of the toolpath to improve his higher order continuity. Others, like M. Bieterman, build directly a C2 spiral tool path with low curvature (this strategy propose to solve numerically a 2D Partial Differential Equation problem and to use the iso-curves as structure curves to build the spiral). These strategies are efficient for High Speed Milling but leads to much longer toolpaths, so it can’t be necessarily a beneficial *** goal of this paper is to compare, for 2D1/2 pocket roughing, the time performance of different machining strategies: “zig-zag”, “contour parallel”, morph spiral and “Bieterman” used on different homothetic rectangular pockets. For this purpose, VPOp software developed in the LURPA lab from Cachan is used. With this procedure, it will be possible to see, for which ratios of size, a milling strategy is efficient or not.

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Corner smoothing of 2D milling toolpath using b-spline curve by optimizing the contour error and the feedrate

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AIP Conference Proceedings 2018年第1期1960卷

作者： Abdullah Özcan Edouard Rivière-Lorphèvre François Ducobu 1University of Mons Machine Design and Production Engineering Lab Place du Parc 20 7000 Mons Belgium

In part manufacturing, efficient process should minimize the cycle time needed to reach the prescribed quality on the part. In order to optimize it, the machining time needs to be as low as possible and the quality needs to meet some requirements. For a 2D milling toolpath defined by sharp corners, the programmed feedrate is different from the reachable feedrate due to kinematic limits of the motor drives. This phenomena leads to a loss of productivity. Smoothing the toolpath allows to reduce significantly the machining time but the dimensional accuracy should not be neglected. Therefore, a way to address the problem of optimizing a toolpath in part manufacturing is to take into account the manufacturing time and the part quality. On one hand, maximizing the feedrate will minimize the manufacturing time and, on the other hand, the maximum of the contour error needs to be set under a threshold to meet the quality requirements. This paper presents a method to optimize sharp corner smoothing using b-spline curves by adjusting the control points defining the curve. The objective function used in the optimization process is based on the contour error and the difference between the programmed feedrate and an estimation of the reachable feedrate. The estimation of the reachable feedrate is based on geometrical information. Some simulation results are presented in the paper and the machining times are compared in each cases.

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The CEL Method as an Alternative to the Current Modelling Approaches for Ti6Al4V Orthogonal Cutting Simulation

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Procedia CIRP 2017年 58卷 245-250页

作者： F. Ducobu P.-J. Arrazola E. Rivière-Lorphèvre G. Ortiz de Zarate A. Madariaga E. Filippi University of Mons (UMONS) Faculty of Engineering (FPMs) Machine Design and Production Engineering Lab 20 Place du Parc B-7000 Mons Belgium Mondragon University Faculty of Engineering Mechanical and Manufacturing Department Mondragón 20500 Spain

The finite element approach is often adopted to study the machining process. The Lagrangian and Eulerian formulations or even Arbitrary Eulerian-Lagrangian (ALE), one of their combinations, are the most employed in the current literature; each having their pros and cons. One of the most challenging issue in finite element modelling is the large strains during the cutting process that induce high deformation levels in the elements of the mesh. Remeshing contributes to decreasing mesh deformation but the criterion adopted to control it influences the results. The Coupled Eulerian-Lagrangian (CEL) method proposes to combine the Lagrangian and Eulerian formalisms without any element deformation problem. This paper studies its implementation in Ti6Al4 V orthogonal cutting. The results are then compared to an experimental reference, as well as more standard models: an ALE model developed with Abaqus, an implicit Lagrangian model developed with Deform and an explicit Lagrangian model developed with AdvantEdge. The comparison is mainly based on the cutting forces and the chip morphology. It shows that the CEL formulation is a competitive alternative to the more standard models.

关键词： Finite element method (FEM) Machining Titanium

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Finite-element simulations of Al7075-T6 orthogonal cutting: Effect of part geometry and mesh on chip morphology and formation mechanism

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AIP Conference Proceedings 2019年第1期2113卷

作者： Mehdi Benhassine Edouard Rivière-Lorphèvre Pedro-Jose Arrazola Pierre Gobin Aurélie Granjon Ohian Aizpuru François Ducobu 1Machine Design and Production Engineering Lab Faculty of Engineering University of Mons (UMONS). Place du Parc 20 7000 Mons BELGIUM 2Mechanical and Manufacturing Department Faculty of Engineering Mondragon University. 20500 Mondragon SPAIN 3Sobelcomp SPRL. Rue de l’économie 13 4431 Loncin BELGIUM 4Zubiola. Poligono Basterretxe 20720 Azkoitia (Gipuzkoa) SPAIN

Machining of aluminum alloys is of great interest for the aeronautical industry. Amongst those, the Al7075-T6 alloy remains a major component. Numerical studies of the orthogonal cutting of such alloys present a few challenges. One of them seems to be the absence of a unified way to capture the chip morphology without artificially modifying the mesh or the piece geometry to facilitate a segmented chip formation. It is accepted that Al7075-T6 forms segmented chips for typical industrial cutting speeds. In this contribution, a FEM model with a structured mesh is used with the commercial code Abaqus/Explicit v6.14 in the Lagrangian scheme. With this straight-forward approach, it is possible to reproduce the cutting forces and the chip morphology obtained in practical cases. The results are validated against experimental tests found in the literature.

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Impact of chemical polishing on surface roughness and dimensional quality of electron beam melting process (EBM) parts

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AIP Conference Proceedings 2018年第1期1960卷

作者： Adrien Dolimont Edouard Rivière-Lorphèvre François Ducobu Stéphane Backaert 1Corresponding author : Machine Design and Production Engineering Lab - Faculty of Engineering - University of Mons Place du parc 20 7000 Mons Belgium 2SAFRAN AERO BOOSTERS Route de Liers 121 4041 Herstal (Milmort) Belgium

Additive manufacturing is growing faster and faster. This leads us to study the functionalization of the parts that are produced by these processes. Electron Beam melting (EBM) is one of these technologies. It is a powder based additive manufacturing (AM) method. With this process, it is possible to manufacture high-density metal parts with complex topology. One of the big problems with these technologies is the surface finish. To improve the quality of the surface, some finishing operations are needed. In this study, the focus is set on chemical polishing. The goal is to determine how the chemical etching impacts the dimensional accuracy and the surface roughness of EBM parts. To this end, an experimental campaign was carried out on the most widely used material in EBM, Ti6Al4V. Different exposure times were tested. The impact of these times on surface quality was evaluated. To help predicting the excess thickness to be provided, the dimensional impact of chemical polishing on EBM parts was estimated. 15 parts were measured before and after chemical machining. The improvement of surface quality was also evaluated after each treatment.

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Development of the hybrid sequential machining: Laser machining and milling 16

Development of the hybrid sequential machining: Laser machin...

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16th International Conference of the European Society for Precision engineering and Nanotechnology, EUSPEN 2016

作者： Demarbaix, Anthonin Rivière-Lorphèvre, Edouard Ducobu, François Filippi, Enrico Petit, Fabrice Preux, Nicolas Univesity of Mons- Faculty of Engineering-Machine Design and Production Engineering Lab Place du Parc 20 Mons7000 Belgium BCRC-INISMa Research and Technological Support Department Av. Gouverneur Cornez 4 Mons7000 Belgium

ISBN: (纸本)9780956679086

The demand of micro products has increased significantly in recent years. The traditional stand- Alone machine tools were optimized to market demands. These processes still remains a big issue in the repeatability, predictability and the productivity of manufacturing. Today, the machine tools are combined to increase the productivity of manufacturing. These hybrid processes are decomposed in three domains: The assisted hybrid, the mixed hybrid and the sequential hybrid. The sequential hybrid is the combination of the minimum of two technologies in the same structure. The different processes must be mastered before the combination. The aims of this paper is to study the advantages and disadvantages of laser micro-machining and the micro-milling. The final goal is to couple these processes in the same structure. The sequential hybrid process is subtractive-subtractive it combines the laser μ-machining and theμ-milling. The samples are machined with the two processes to compare the dimensional tolerance and the geometrical tolerance of fundamental geometries.

关键词： Milling (machining)

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