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| 2. |
- Agmell, Mathias, et al.
(författare)
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A fully coupled thermomechanical two-dimensional simulation model for orthogonal cutting: formulation and simulation
- 2011
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Ingår i: Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture. - : SAGE Publications. - 0954-4054 .- 2041-2975. ; 225:B10, s. 1735-1745
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Tidskriftsartikel (refereegranskat)abstract
- In this paper a fully coupled thermomechanical two-dimensional simulation model for orthogonal cutting is presented. The model is based on the arbitrary Lagrangian-Eulerian formulation with the remeshing technique. The material model used for the workpiece material includes Johnson-Cook plasticity, and as the chip separation criterion the Johnson-Cook damage law is employed. The different friction zones are modelled by the Coulomb friction law with a maximum limit for the friction. The capability of the model to represent the cutting process realistically is validated by performing simulations for different feed depths. The model is validated by comparison of the simulated values and measured experimental data for several different important process parameters, such as the feed force, the cutting force, the chip thickness ratio, the relative deformation widths, and the temperature distribution. The results from the simulations showed very good agreement with the experimental data.
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| 3. |
- Agmell, Mathias, et al.
(författare)
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A numerical and experimental investigation of the deformation zones and the corresponding cutting forces in orthogonal cutting
- 2011
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Ingår i: Advanced Materials Research. - 1022-6680 .- 1662-8985. - 9783037850954 ; 223, s. 152-161
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Konferensbidrag (refereegranskat)abstract
- Abstract in UndeterminedThis study are focused on the deformation zones occurring in the work piece in a machining process and the corresponding cutting forces. The fully coupled thermo-mechanical FE-model for orthogonal cutting, developed in [1] is utilized. The work piece material is modeled with Johnson-Cook plasticity including damage formulation. Simulations for different feed depths were performed. The cutting forces, the chip thickness ratio and the deformation widths were determined experimentally by the quick-stop images and a force measurements. The results from the simulations have been compared to experimental data for the cutting forces and the chip thickness ratio as a function of the theoretical chip thickness.
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| 4. |
- Agmell, Mathias, et al.
(författare)
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Development of a simulation model to study tool loads in pcBN when machining AISI 316L
- 2018
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Ingår i: International Journal of Advanced Manufacturing Technology. - : Springer Science and Business Media LLC. - 0268-3768 .- 1433-3015. ; 96:5-8, s. 2853-2865
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents the development of a FE-simulation model to predict the mechanical stresses and thermal loads that a cutting tool of polycrystalline cubic boron nitride (pcBN) is subjected to, when machining AISI 316L. The serrated chip formation of AISI 316L has a major impact on the periodic loads acting on the cutting tool. Therefore, it is vital to correctly model this serrated chip formation. One of the major difficulties with FE-simulations of metal cutting is that the extreme deformations in the workpiece material, often leads to a highly distorted mesh. This paper uses the Coupled Eulerian-Lagrangian (CEL) formulation in Abaqus/Explicit, where the workpiece is modelled with the Eulerian formulation and the cutting tool by the Lagrangian one. This CEL formulation enables to completely avoid mesh distortion. To capture the chip serration process, the workpiece material is described with the Johnson-Cook damage model. The FE-simulation results are validated via comparison of the modelled cutting forces, chip serration frequency, and contact length against experimental ones.
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| 5. |
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| 6. |
- Agmell, Mathias, et al.
(författare)
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Identification of plasticity constants from orthogonal cutting and inverse analysis
- 2014
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Ingår i: Mechanics of Materials. - : Elsevier BV. - 0167-6636. ; 77, s. 43-51
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this work is that from experimental determined cutting process parameters be able to predict the plasticity input constants to Finite Element Method (FEM) models. In the present study the Johnson-Cook constitutive model constants are determined on the basis of cutting process parameters in orthogonal cutting and by use of inverse analysis. Previously established links between Johnson-Cook constitutive model constants and cutting process parameters in the cutting process such as primary cutting force and chip compression ratio is used serve as a starting point in the inverse analysis. As a reference material AISI 4140 has been chosen in this study, which is a tempered steel. The Johnson-Cook constitutive model constants in the reference material are being changed within an interval of ±30 %. The inverse analysis is performed using a Kalman filter. The material model for the reference material is validated on the basis of the experimental results in previous work. The model showed to predict the cutting process parameters with a high level of accuracy. The predicted Johnson-Cook constitutive model constants in the present study achieve an error between simulated- and experimental cutting process parameters of maximum 2%. The method described in this study is not limited to identify Johnson-Cook constitutive model constants, but the method can also be used for other constitutive models. The same applies to the process itself and the selected cutting process parameters, but orthogonal cutting has been used to illustrate and validate this method.
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| 7. |
- Agmell, Mathias, et al.
(författare)
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Modelling Subsurface Deformation in High Speed Machining of Inconel 718
- 2012
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Konferensbidrag (refereegranskat)abstract
- Abstract in UndeterminedTraditionally, the development and optimization of the machining process with regards to the sub-surface deformation is done through experimental method which is often expensive and time consume. This paper presents the development of a FE-simulation model to predict the depth of sub-surface deformation induced in the high speed machining of Inconel 718 by use of whisker-reinforced ceramic tool. The effects of cutting parameters and geometry on sub-surface deformation will be simulated by developed FE model. In addition to FE model, the experimental study was made to validate the results of FE model. Characterization of sub-surface deformation produced under different machining parameters and tool conditions was made by EBSD and in the cutting and feed directions.
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| 8. |
- Agmell, Mathias, et al.
(författare)
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The influence of tool micro-geometry on stress distribution in turning operations of AISI 4140 by FE analysis
- 2017
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Ingår i: International Journal of Mechanical Sciences. - : Springer Science and Business Media LLC. - 1879-2162. ; 89:9-12, s. 3109-3122
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Tidskriftsartikel (refereegranskat)abstract
- Abstract This paper aims to gain a better understanding of the impact different micro-geometries has on stress distribution in cutting tools. Both principal and effective stress distribution are studied since these quantities have a major impact on the occurrence of damages in the cutting tool such as crack formation, flaking, chipping, breakage and plastic deformation. The development of a stagnation zone has also been investigated and the effect tool micro-geometries have on this zone. A finite element model has been developed which enables the examination of these aspects, in detail. The model was able to predict these metal cutting phenomena with high accuracy. Cutting forces is within the standard deviation of experimental results, stress distributions and the stagnation zone is also simulated correctly indicated by experimental results. This study has shown that the micro-geometries of the cutting tool have a great potential in order to reduce the maximal tensile/principal stress. This research work also shows that the size of the stagnation zone can be controlled by micro-geometries on the cutting tool, which can have an effect on the wear on the cutting edge.
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| 9. |
- Agmell, Mathias, et al.
(författare)
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The Influence the Uncut Chip Thickness has on the Stagnation Point in Orthogonal Cutting
- 2017
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Ingår i: 16th CIRP Conference on Modelling of Machining Operations (16th CIRP CMMO). - : Elsevier BV. - 2212-8271. - 9781510842762 ; 58, s. 13-18
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Konferensbidrag (refereegranskat)abstract
- The effect of cutting data on the stagnation zone of a machining operation is of great interest since it governs the material flow around the cutting edge. The material flow has a significant influence on the mechanical properties of the machined surface. This paper presents a numerical model that is able to determine the effect that the uncut chip thickness has on the stagnation zone and the connection between the stagnation zone and the deformation layer in the machined subsurface.
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| 10. |
- Agmell, Mathias, et al.
(författare)
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The link between plasticity parameters and process parameters in orthogonal cutting
- 2013
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Ingår i: 14th CIRP Conference on Modeling of Machining Operations (CIRP CMMO). - : Elsevier BV. - 2212-8271. ; 8, s. 224-229
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Konferensbidrag (refereegranskat)abstract
- In the present study the plasticity parameters in the Johnson Cook plasticity model are determined on the basis of process parameters in orthogonal cutting by use of inverse analysis. Previously established links between material parameters and process parameters in the cutting process such as chip thickness ratio, cutting forces, temperatures, deformation zones, is used serve as a starting point in the inverse analysis. The material AISI 4140 is simulated using the model employed in [1], the Johnson Cook parameters being changed within an interval of ±30 %. The inverse analysis is performed using a Kalman filter. The material model for the reference point is validated on the basis of the experimental results in [1], the model being shown to predict the process parameters with a high level of accuracy. The attempt is made to establish a link for materials having cutting process characteristics that are similar between certain process parameters and the Johnson Cook parameters in order to be able to predict the input parameters to FEM models using experimental data from a cutting process.
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