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The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material.Wed, 21 Feb 2024 04:09:08 GMT2024-02-21T04:09:08ZParts internal structure definition using lattice patterns optimization for mass reduction in additive manufacturing
http://hdl.handle.net/10985/11408
Parts internal structure definition using lattice patterns optimization for mass reduction in additive manufacturing
CHOUGRANI, Laurent; VERON, Philippe; ABED, Stéphane; PERNOT, Jean-Philippe
With the rise of additive manufacturing, complex internal structure optimization is now a relevant topic. Additive manufacturing allows designers and engineers to go further in their modeling, designing and optimization process, allowing new complex shapes to be produced, including the optimization of their internal structure. However modeling, design and optimization tools still represent a limitation to that new horizon of printable shapes. In this article, we define the framework in term of new designs, 3D modeling and optimization approach dedicated to the shape definition of patterned (or organized) lattice structures1 produced using additive manufacturing processes. The goal being to generate shapes that fit the mechanical requirements with an “as reduced as possible” mass, this issue is still today a niche market for Aerospace and Automotive, but could soon lead to a wider range of applications. Optimizing topology can be slow, so we will show a way of reducing computation time by using relative criteria for removing material. This new approach is based on the use of organized lattice structures to allow a wide range of shapes, thus opening the field for finding better optimized shapes. Once the patterned lattice structure is defined, it is send to a Finite Element solver software that returns the constraints and/or displacements map. This is then used as a basis for a statistical calculus that determines the elements that can or cannot be removed from the lattice. After a few iterations, the general structure is no longer patterned, but organized in a way that suits its mechanical environment, allowing lighter general structure and ensuring its rigidity. This approach is illustrated with examples coming from a prototype software.
Fri, 01 Jan 2016 00:00:00 GMThttp://hdl.handle.net/10985/114082016-01-01T00:00:00ZCHOUGRANI, LaurentVERON, PhilippeABED, StéphanePERNOT, Jean-PhilippeWith the rise of additive manufacturing, complex internal structure optimization is now a relevant topic. Additive manufacturing allows designers and engineers to go further in their modeling, designing and optimization process, allowing new complex shapes to be produced, including the optimization of their internal structure. However modeling, design and optimization tools still represent a limitation to that new horizon of printable shapes. In this article, we define the framework in term of new designs, 3D modeling and optimization approach dedicated to the shape definition of patterned (or organized) lattice structures1 produced using additive manufacturing processes. The goal being to generate shapes that fit the mechanical requirements with an “as reduced as possible” mass, this issue is still today a niche market for Aerospace and Automotive, but could soon lead to a wider range of applications. Optimizing topology can be slow, so we will show a way of reducing computation time by using relative criteria for removing material. This new approach is based on the use of organized lattice structures to allow a wide range of shapes, thus opening the field for finding better optimized shapes. Once the patterned lattice structure is defined, it is send to a Finite Element solver software that returns the constraints and/or displacements map. This is then used as a basis for a statistical calculus that determines the elements that can or cannot be removed from the lattice. After a few iterations, the general structure is no longer patterned, but organized in a way that suits its mechanical environment, allowing lighter general structure and ensuring its rigidity. This approach is illustrated with examples coming from a prototype software.Investigation on reducing geometry files size through floating points indexing
http://hdl.handle.net/10985/16980
Investigation on reducing geometry files size through floating points indexing
VAISSIER, Benjamin; CHOUGRANI, Laurent; VERON, Philippe; PERNOT, Jean-Philippe
In a context of full cooperative data exchanges, frequent transfers between specialized software and remote design and manufacturing, fluidity is the key. It is thus important to reduce the size of data encoding files in order to ease their manipulation. In particular, in the case of 3D-geometry-based processes, triangulated meshes are often used. In such files, the 3D points are localized in space thanks to three coordinates. In order to reduce the size of geometry files, this paper investigates the use of an indexing mechanism to encode these floating-point coordinates.
Tue, 01 Jan 2019 00:00:00 GMThttp://hdl.handle.net/10985/169802019-01-01T00:00:00ZVAISSIER, BenjaminCHOUGRANI, LaurentVERON, PhilippePERNOT, Jean-PhilippeIn a context of full cooperative data exchanges, frequent transfers between specialized software and remote design and manufacturing, fluidity is the key. It is thus important to reduce the size of data encoding files in order to ease their manipulation. In particular, in the case of 3D-geometry-based processes, triangulated meshes are often used. In such files, the 3D points are localized in space thanks to three coordinates. In order to reduce the size of geometry files, this paper investigates the use of an indexing mechanism to encode these floating-point coordinates.Lattice structure lightweight triangulation for additive manufacturing
http://hdl.handle.net/10985/14256
Lattice structure lightweight triangulation for additive manufacturing
CHOUGRANI, Laurent; VERON, Philippe; ABED, Stéphane; PERNOT, Jean-Philippe
Additive manufacturing offers new available categories of geometries to be built. Among those categories, one can find the well developing field of lattice structures. Attention has been paid on lattice structures for their lightweight and mechanical efficiency ratio, thus leading to more optimized mechanical parts for systems. However this lightness only holds true from a mass related point of view. The files sent to additive manufacturing machines are quite large and can go up to such sizes that machines can freeze and get into malfunction. This is directly related to the lattice structures tendency to be of a high geometric complexity. a large amount of vertices and triangles is necessary to describe them geometrically, thus leading to larger file sizes. With the increasing use of lattice structures, the need for their files to be lighter is also rising. This paper aims at proposing a method for tessellating a certain category of such structures, using topologic and geometric criteria to generate as few as possible triangles, thus leading to lightweight files. The triangulation technique is driven by a chordal error that control the deviation between the exact and tessellated structures. It uses interpolation, boolean as well as triangulation operators. The method is illustrated and discussed through examples from our prototype software.
Sun, 01 Jan 2017 00:00:00 GMThttp://hdl.handle.net/10985/142562017-01-01T00:00:00ZCHOUGRANI, LaurentVERON, PhilippeABED, StéphanePERNOT, Jean-PhilippeAdditive manufacturing offers new available categories of geometries to be built. Among those categories, one can find the well developing field of lattice structures. Attention has been paid on lattice structures for their lightweight and mechanical efficiency ratio, thus leading to more optimized mechanical parts for systems. However this lightness only holds true from a mass related point of view. The files sent to additive manufacturing machines are quite large and can go up to such sizes that machines can freeze and get into malfunction. This is directly related to the lattice structures tendency to be of a high geometric complexity. a large amount of vertices and triangles is necessary to describe them geometrically, thus leading to larger file sizes. With the increasing use of lattice structures, the need for their files to be lighter is also rising. This paper aims at proposing a method for tessellating a certain category of such structures, using topologic and geometric criteria to generate as few as possible triangles, thus leading to lightweight files. The triangulation technique is driven by a chordal error that control the deviation between the exact and tessellated structures. It uses interpolation, boolean as well as triangulation operators. The method is illustrated and discussed through examples from our prototype software.Parametric design of graded truss lattice structures for enhanced thermal dissipation
http://hdl.handle.net/10985/16741
Parametric design of graded truss lattice structures for enhanced thermal dissipation
VAISSIER, Benjamin; CHOUGRANI, Laurent; VERON, Philippe; PERNOT, Jean-Philippe
Truss lattice structures are intricate geometries, whose fabrication has recently been simplified by the development of Additive Manufacturing (AM) technologies. These lightweight geometries present great volume densities and surface-to-occupancy ratios, which makes them ideal for thermal dissipation applications. This paper introduces a new framework for the parametric design of graded truss lattice structures that maximize passive cooling. It exploits the results of a semi-analytic formulation and analysis of the volume density and surface-to-occupancy ratio of state-of-the-art unit cells. In particular, it comes out that any truss lattice structure presents an optimal beam diameter over unit cell size ratio that maximizes its surface-to-occupancy value. This value and the ratio for which it is reached are identified and compared for the most common unit cells. The unit cell with the maximal surface-to-occupancy ratio is then identified, along with its set of optimal parameters, taking into account additive manufacturing constraints. The validation of this optimal geometry is performed by populating pre-defined design spaces of both academic and industrial case studies. An orientation strategy and a parametric gradation approach are also proposed to further optimize the generated heat sinks and maximize passive cooling. These results are very helpful to support decision making during the parametric design of a heat sink and to identify, a priori, the optimal unit cell, its control parameters, its orientation and its gradation strategy. The generated geometries are compared with traditional heat sink structures through static heat dissipation simulations, in order to demonstrate their interest.
Tue, 01 Jan 2019 00:00:00 GMThttp://hdl.handle.net/10985/167412019-01-01T00:00:00ZVAISSIER, BenjaminCHOUGRANI, LaurentVERON, PhilippePERNOT, Jean-PhilippeTruss lattice structures are intricate geometries, whose fabrication has recently been simplified by the development of Additive Manufacturing (AM) technologies. These lightweight geometries present great volume densities and surface-to-occupancy ratios, which makes them ideal for thermal dissipation applications. This paper introduces a new framework for the parametric design of graded truss lattice structures that maximize passive cooling. It exploits the results of a semi-analytic formulation and analysis of the volume density and surface-to-occupancy ratio of state-of-the-art unit cells. In particular, it comes out that any truss lattice structure presents an optimal beam diameter over unit cell size ratio that maximizes its surface-to-occupancy value. This value and the ratio for which it is reached are identified and compared for the most common unit cells. The unit cell with the maximal surface-to-occupancy ratio is then identified, along with its set of optimal parameters, taking into account additive manufacturing constraints. The validation of this optimal geometry is performed by populating pre-defined design spaces of both academic and industrial case studies. An orientation strategy and a parametric gradation approach are also proposed to further optimize the generated heat sinks and maximize passive cooling. These results are very helpful to support decision making during the parametric design of a heat sink and to identify, a priori, the optimal unit cell, its control parameters, its orientation and its gradation strategy. The generated geometries are compared with traditional heat sink structures through static heat dissipation simulations, in order to demonstrate their interest.Genetic-algorithm based framework for lattice support structure optimization in additive manufacturing
http://hdl.handle.net/10985/16940
Genetic-algorithm based framework for lattice support structure optimization in additive manufacturing
VAISSIER, Benjamin; CHOUGRANI, Laurent; VERON, Philippe; PERNOT, Jean-Philippe
The emergence and improvement of Additive Manufacturing technologies allow the fabrication of complex shapes so far inconceivable. However, to produce those intricate geometries, support structures are required. Besides wasting unnecessary material, these structures are consuming valuable production and post-processing times. This paper proposes a new framework to optimize the geometry and topology of inner and outer support structures. Starting from a uniform lattice structure filling both the inner and outer areas to be supported, the approach removes a maximum number of beams so as to minimize the volume of the support. The most suited geometry for the initial lattice structure is defined at the beginning considering the possibilities of the manufacturing technologies. Then, the pruning of the structure is performed through a genetic algorithm, for which the control parameters values have been tuned through a design of experiments. The proposed approach is validated on several test cases of various geometries, containing both inner and outer areas to be supported. The generated support structures are compared to the ones obtained by several state-of-the-art support structure strategies and are proved to have lower material consumption.
Tue, 01 Jan 2019 00:00:00 GMThttp://hdl.handle.net/10985/169402019-01-01T00:00:00ZVAISSIER, BenjaminCHOUGRANI, LaurentVERON, PhilippePERNOT, Jean-PhilippeThe emergence and improvement of Additive Manufacturing technologies allow the fabrication of complex shapes so far inconceivable. However, to produce those intricate geometries, support structures are required. Besides wasting unnecessary material, these structures are consuming valuable production and post-processing times. This paper proposes a new framework to optimize the geometry and topology of inner and outer support structures. Starting from a uniform lattice structure filling both the inner and outer areas to be supported, the approach removes a maximum number of beams so as to minimize the volume of the support. The most suited geometry for the initial lattice structure is defined at the beginning considering the possibilities of the manufacturing technologies. Then, the pruning of the structure is performed through a genetic algorithm, for which the control parameters values have been tuned through a design of experiments. The proposed approach is validated on several test cases of various geometries, containing both inner and outer areas to be supported. The generated support structures are compared to the ones obtained by several state-of-the-art support structure strategies and are proved to have lower material consumption.Lightweight Mesh File Format Using Repetition Pattern Encoding for Additive Manufacturing
http://hdl.handle.net/10985/19955
Lightweight Mesh File Format Using Repetition Pattern Encoding for Additive Manufacturing
VAISSIER, Benjamin; CHOUGRANI, Laurent; VÉRON, Philippe; PERNOT, Jean-Philippe
To facilitate the transfer, storage and manipulation of intricate parts’ geometry whose fabrication has been made possible thanks to the rise of Additive Manufacturing (AM) technologies, an encoding framework reducing the resulting file size has been developed. This approach leverages the fact that many AM parts are presenting repetition patterns, by encoding the repetition of similar geometry chunks. The decomposition of the part into chunks is a complex optimization problem, whose identification as a Weighted Exact Cover (WEC) problem allowed to develop a new heuristic algorithm dedicated to its fast resolution in linear time . The encoding strategy is implemented through a variation of the AMF file standard (for quick adoption of the format by existing software), and also through a new ad-hoc hybrid file format. To demonstrate the efficiency of the approach, the encryption of lattice and support structures through these two encoding strategies are compared to the results of several state-of-the-art encoding approaches. The way this data weight lightening strategy preserves the overall accuracy is discussed while considering different floating points encoding precisions with respect to the AM process requirements. This comparison exhibits file size reductions up to -84% in comparison with file sizes generated by state-of-the-art approaches. Not only the proposed repetition pattern encoding framework allows file size reductions, but it could also be exploited to optimize and speed-up some steps of the Product Development Process (PDP), including process planning phases.
Wed, 01 Jan 2020 00:00:00 GMThttp://hdl.handle.net/10985/199552020-01-01T00:00:00ZVAISSIER, BenjaminCHOUGRANI, LaurentVÉRON, PhilippePERNOT, Jean-PhilippeTo facilitate the transfer, storage and manipulation of intricate parts’ geometry whose fabrication has been made possible thanks to the rise of Additive Manufacturing (AM) technologies, an encoding framework reducing the resulting file size has been developed. This approach leverages the fact that many AM parts are presenting repetition patterns, by encoding the repetition of similar geometry chunks. The decomposition of the part into chunks is a complex optimization problem, whose identification as a Weighted Exact Cover (WEC) problem allowed to develop a new heuristic algorithm dedicated to its fast resolution in linear time . The encoding strategy is implemented through a variation of the AMF file standard (for quick adoption of the format by existing software), and also through a new ad-hoc hybrid file format. To demonstrate the efficiency of the approach, the encryption of lattice and support structures through these two encoding strategies are compared to the results of several state-of-the-art encoding approaches. The way this data weight lightening strategy preserves the overall accuracy is discussed while considering different floating points encoding precisions with respect to the AM process requirements. This comparison exhibits file size reductions up to -84% in comparison with file sizes generated by state-of-the-art approaches. Not only the proposed repetition pattern encoding framework allows file size reductions, but it could also be exploited to optimize and speed-up some steps of the Product Development Process (PDP), including process planning phases.Parts internal structure definition using non-uniform patterned lattice optimization for mass reduction in additive manufacturing
http://hdl.handle.net/10985/13936
Parts internal structure definition using non-uniform patterned lattice optimization for mass reduction in additive manufacturing
CHOUGRANI, Laurent; VERON, Philippe; ABED, Stéphane; PERNOT, Jean-Philippe
Today, being able to generate and produce shapes that fit mechanical and functional requirements and having as low as possible mass is crucial for aerospace and automotive applications. Besides, the rise of new additive manufacturing technologies has widened the possibilities for designing and producing complex shapes and internal structures. However, current models, methods and tools still represent a limitation to that new horizon of printable shapes. This paper addresses the way internal lattice structures can be generated and optimized to reduce the mass of a product. A new framework is introduced that allows the modeling and optimization of non-uniform patterned lattice structures. Using non-uniform structures, additional degrees of freedom are introduced and allow the definition of a wide variety of shapes which can better fit the requirements. First, a non-uniform patterned lattice structure is generated using the results of an initial finite element analysis. This initial structure is then optimized while iteratively removing the beams considered as useless with respect to a user-specified mechanical criteria. At each iteration, the lattice structure is sent to a finite element solver that returns the von Mises stress map used to drive the simplification process. Here, the simulations are performed on the wireframe lattice structures to speed up the optimization loops. Once this process is completed, the final structure is no longer fully patterned, but it is re-organized to reduce the mass while satisfying the mechanical criteria. This approach is illustrated with examples coming from our prototype software.
Mon, 01 Jan 2018 00:00:00 GMThttp://hdl.handle.net/10985/139362018-01-01T00:00:00ZCHOUGRANI, LaurentVERON, PhilippeABED, StéphanePERNOT, Jean-PhilippeToday, being able to generate and produce shapes that fit mechanical and functional requirements and having as low as possible mass is crucial for aerospace and automotive applications. Besides, the rise of new additive manufacturing technologies has widened the possibilities for designing and producing complex shapes and internal structures. However, current models, methods and tools still represent a limitation to that new horizon of printable shapes. This paper addresses the way internal lattice structures can be generated and optimized to reduce the mass of a product. A new framework is introduced that allows the modeling and optimization of non-uniform patterned lattice structures. Using non-uniform structures, additional degrees of freedom are introduced and allow the definition of a wide variety of shapes which can better fit the requirements. First, a non-uniform patterned lattice structure is generated using the results of an initial finite element analysis. This initial structure is then optimized while iteratively removing the beams considered as useless with respect to a user-specified mechanical criteria. At each iteration, the lattice structure is sent to a finite element solver that returns the von Mises stress map used to drive the simplification process. Here, the simulations are performed on the wireframe lattice structures to speed up the optimization loops. Once this process is completed, the final structure is no longer fully patterned, but it is re-organized to reduce the mass while satisfying the mechanical criteria. This approach is illustrated with examples coming from our prototype software.