https://sam.ensam.eu:443 The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material. Fri, 12 Jun 2026 11:29:50 GMT 2026-06-12T11:29:50Z http://hdl.handle.net/10985/8325 Direct modification of semanticaly-enriched finite element meshes GIANNINI, Franca; FALCIDIENO, Bianca; MIKCHEVITCH, Alexei; MARC, Raphael; PERNOT, Jean-Philippe; LOU, Ruding; VERON, Philippe Behaviour analysis loop is largely performed on virtual product model before its physical manufacturing. The last avoids high expenses in terms of money and time spent on intermediate manufacturing. It is gainful from the reality to the virtuality but the process could be further optimized especially during the product behaviour optimization phase. This process involves repetition of four main processing steps: CAD design and modification, mesh creation, Finite Element (FE) model generation with the association of physical and geometric data, FE Analysis. The product behaviour analysis loop is performed on the rst design solution as well as on the numerous successive product optimization loops. Each design solution evaluation necessitates the same time as required for the first product design that is particularly crucial in the context of maintenance. In this paper we propose a new framework for CAD-less product optimisation through FE analysis which reduces the model preparation activities traditionally required for FE model creation. More concretely, the idea is to directly operate on the rstly created FE mesh, enriched with physical/geometric semantics, to perform the product modi cations required to achieve its optimised version. In order to accomplish the proposed CAD-less FE analysis framework, modification operators acting on both the mesh geometry and the associated semantics need to be devised. In this paper we discuss the underlying concepts and present possible components for the development of such operators. A high-level operator speci cation is proposed according to a modular structure that allows an easy realisation of di erent mesh modification operators. Here, two instances of this high-level operator are described: the planar cracking and the drilling. The realised prototypes validated on industrial FE models show clearly the feasibility of this approach. Fri, 01 Jan 2010 00:00:00 GMT http://hdl.handle.net/10985/8325 2010-01-01T00:00:00Z GIANNINI, Franca FALCIDIENO, Bianca MIKCHEVITCH, Alexei MARC, Raphael PERNOT, Jean-Philippe LOU, Ruding VERON, Philippe Behaviour analysis loop is largely performed on virtual product model before its physical manufacturing. The last avoids high expenses in terms of money and time spent on intermediate manufacturing. It is gainful from the reality to the virtuality but the process could be further optimized especially during the product behaviour optimization phase. This process involves repetition of four main processing steps: CAD design and modification, mesh creation, Finite Element (FE) model generation with the association of physical and geometric data, FE Analysis. The product behaviour analysis loop is performed on the rst design solution as well as on the numerous successive product optimization loops. Each design solution evaluation necessitates the same time as required for the first product design that is particularly crucial in the context of maintenance. In this paper we propose a new framework for CAD-less product optimisation through FE analysis which reduces the model preparation activities traditionally required for FE model creation. More concretely, the idea is to directly operate on the rstly created FE mesh, enriched with physical/geometric semantics, to perform the product modi cations required to achieve its optimised version. In order to accomplish the proposed CAD-less FE analysis framework, modification operators acting on both the mesh geometry and the associated semantics need to be devised. In this paper we discuss the underlying concepts and present possible components for the development of such operators. A high-level operator speci cation is proposed according to a modular structure that allows an easy realisation of di erent mesh modification operators. Here, two instances of this high-level operator are described: the planar cracking and the drilling. The realised prototypes validated on industrial FE models show clearly the feasibility of this approach. http://hdl.handle.net/10985/9336 Filleting sharp edges of multi-partitioned volume finite element meshes GIANNINI, Franca; FALCIDIENO, Bianca; PERNOT, Jean-Philippe; LOU, Ruding; VERON, Philippe Purpose – The purpose of this paper is to set up a new framework to enable direct modifications of volume meshes enriched with semantic information associated to multiple partitions. An instance of filleting operator is prototyped under this framework and presented in the paper. Design/methodology/approach – In this paper, a generic mesh modification operator has been designed and a new instance of this operator for filleting finite element (FE) sharp edges of tetrahedral multi-partitioned meshes is also pro-posed. The filleting operator works in two main steps. The outer skin of the tetrahedral mesh is first deformed to round user-specified sharp edges while satisfying constraints relative to the shape of the so-called Virtual Group Boundaries. Then, in the filleting area, the positions of the inner nodes are relaxed to improve the aspect ratio of the mesh elements. Findings – The classical mainstream methodology for product behaviour optimization involves the repetition of four steps: CAD modelling, meshing of CAD models, enrichment of models with FE simulation semantics and FEA. This paper highlights how this methodology could be simplified by two steps: simulation model modification and FEA. The authors set up a new framework to enable direct modifications of volume meshes enriched with semantic information associated to multiple and the corresponding fillet operator is devised. Research limitations/implications – The proposed framework shows only a paradigm of direct modifications of semantic enriched meshes. It could be further more improved by adding or changing the modules inside. The fillet operator does not take into account the exact radius imposed by user. With this proposed fillet operator the mesh element density may not be enough high to obtain wished smoothness. Originality/value – This paper fulfils an identified industry need to speed up the product behaviour analysis process by directly modifying the simulation semantic enriched meshes. Thu, 01 Jan 2015 00:00:00 GMT http://hdl.handle.net/10985/9336 2015-01-01T00:00:00Z GIANNINI, Franca FALCIDIENO, Bianca PERNOT, Jean-Philippe LOU, Ruding VERON, Philippe Purpose – The purpose of this paper is to set up a new framework to enable direct modifications of volume meshes enriched with semantic information associated to multiple partitions. An instance of filleting operator is prototyped under this framework and presented in the paper. Design/methodology/approach – In this paper, a generic mesh modification operator has been designed and a new instance of this operator for filleting finite element (FE) sharp edges of tetrahedral multi-partitioned meshes is also pro-posed. The filleting operator works in two main steps. The outer skin of the tetrahedral mesh is first deformed to round user-specified sharp edges while satisfying constraints relative to the shape of the so-called Virtual Group Boundaries. Then, in the filleting area, the positions of the inner nodes are relaxed to improve the aspect ratio of the mesh elements. Findings – The classical mainstream methodology for product behaviour optimization involves the repetition of four steps: CAD modelling, meshing of CAD models, enrichment of models with FE simulation semantics and FEA. This paper highlights how this methodology could be simplified by two steps: simulation model modification and FEA. The authors set up a new framework to enable direct modifications of volume meshes enriched with semantic information associated to multiple and the corresponding fillet operator is devised. Research limitations/implications – The proposed framework shows only a paradigm of direct modifications of semantic enriched meshes. It could be further more improved by adding or changing the modules inside. The fillet operator does not take into account the exact radius imposed by user. With this proposed fillet operator the mesh element density may not be enough high to obtain wished smoothness. Originality/value – This paper fulfils an identified industry need to speed up the product behaviour analysis process by directly modifying the simulation semantic enriched meshes. http://hdl.handle.net/10985/10194 Towards a new approach for the description of shapes from multimodal data LI, Zongcheng; GIANNINI, Franca; FALCIDIENO, Bianca; PERNOT, Jean-Philippe; VERON, Philippe The construction of a Virtual Environments (VE) requires a long iterative modeling and modification process. Depending on the final purposes, many actors can be involved both in the early conception and in the detailed specification of what has to be included and how it has to be organized. These actors may have different knowledge and expertise. It is therefore important to define tools easy usable even by nonprofessionals in order to facilitate the VE specification and setup. Such tools should allow the incomplete specification of details and the reuse of existing assets and data, either 2D images or 3D models. In this perspective, the work presented in this paper proposes a new shape description model for the management of objects and assemblies, resulting from the combination of multimodal data, together with their intrinsic properties. Based on such a model high level methods and tools directly working on components (either 2D or 3D) can be developed. Thus making easier the solution specification by the application domain experts, which can thus better integrated within the VE design process. This new shape description model is thought to be used as an intermediary model shared between the various actors in the generation process of VEs to keep the link and digital chain between them. The concepts of this model are proposed and illustrated through a first implementation. Tue, 01 Jan 2013 00:00:00 GMT http://hdl.handle.net/10985/10194 2013-01-01T00:00:00Z LI, Zongcheng GIANNINI, Franca FALCIDIENO, Bianca PERNOT, Jean-Philippe VERON, Philippe The construction of a Virtual Environments (VE) requires a long iterative modeling and modification process. Depending on the final purposes, many actors can be involved both in the early conception and in the detailed specification of what has to be included and how it has to be organized. These actors may have different knowledge and expertise. It is therefore important to define tools easy usable even by nonprofessionals in order to facilitate the VE specification and setup. Such tools should allow the incomplete specification of details and the reuse of existing assets and data, either 2D images or 3D models. In this perspective, the work presented in this paper proposes a new shape description model for the management of objects and assemblies, resulting from the combination of multimodal data, together with their intrinsic properties. Based on such a model high level methods and tools directly working on components (either 2D or 3D) can be developed. Thus making easier the solution specification by the application domain experts, which can thus better integrated within the VE design process. This new shape description model is thought to be used as an intermediary model shared between the various actors in the generation process of VEs to keep the link and digital chain between them. The concepts of this model are proposed and illustrated through a first implementation. http://hdl.handle.net/10985/9777 Towards semantic-based 3D mesh modeling GIANNINI, Franca; MIKCHEVITECH, Alexei; FALCIDIENO, Bianca; MARC, Raphael; PERNOT, Jean-Philippe; LOU, Ruding; VERON, Philippe Nowadays, most of the numerical simulations in product maintenance are carried out by several loops of the following steps: 1) CAD model creation/optimization, 2) Finite Element (FE) mesh generation, 3) insertion of semantic data for physical simulation (e.g. material behavior laws, boundary conditions) and 4) FE simulation and analysis of the results. The four steps are repeated for the evaluation of each conceived maintenance solution. The semantic data are attached to the mesh through the use of groups of mesh entities sharing the same semantic characteristics. Thus, any modification of the CAD model always implies an update of the mesh as well as an update of the attached semantic data. This is time-consuming and thus not suitable for industrial maintenance. Moreover, the CAD models do not always exist and should therefore be reconstructed starting from scratch or from the scanned physical object. In this paper, we propose a framework towards the definition of semantics based CAD-less operators wherein semantic enriched meshes are manipulated directly. This work also finds interest in the preliminary design phases where alternative solutions have to be quickly evaluated Fri, 01 Jan 2010 00:00:00 GMT http://hdl.handle.net/10985/9777 2010-01-01T00:00:00Z GIANNINI, Franca MIKCHEVITECH, Alexei FALCIDIENO, Bianca MARC, Raphael PERNOT, Jean-Philippe LOU, Ruding VERON, Philippe Nowadays, most of the numerical simulations in product maintenance are carried out by several loops of the following steps: 1) CAD model creation/optimization, 2) Finite Element (FE) mesh generation, 3) insertion of semantic data for physical simulation (e.g. material behavior laws, boundary conditions) and 4) FE simulation and analysis of the results. The four steps are repeated for the evaluation of each conceived maintenance solution. The semantic data are attached to the mesh through the use of groups of mesh entities sharing the same semantic characteristics. Thus, any modification of the CAD model always implies an update of the mesh as well as an update of the attached semantic data. This is time-consuming and thus not suitable for industrial maintenance. Moreover, the CAD models do not always exist and should therefore be reconstructed starting from scratch or from the scanned physical object. In this paper, we propose a framework towards the definition of semantics based CAD-less operators wherein semantic enriched meshes are manipulated directly. This work also finds interest in the preliminary design phases where alternative solutions have to be quickly evaluated http://hdl.handle.net/10985/9002 A survey to evaluate how non designers perceive aesthetic properties of styling features GIANNINI, Franca; MONTI, Marina; PELLETIER, Jérôme; PERNOT, Jean-Philippe World-wide market competition and the need to create products that better satisfy the market expectations require a more comprehensive involvement of the customer in the product definition loop. Therefore, it is crucial to provide customers with very easy-to-use shape definition and modification tools, allowing them to verify and evaluate possible shape alternatives without requiring specific knowledge on geometric modeling. A set of aesthetic properties guiding the shape characterization and appraisal have been identified together with measures for their evaluation and shape modeling methods for their direct modification. Since these properties have been indicated by stylists, no guarantee exists that they are usable in a context directly involving customers in the product definition loop. To verify the extent to which the terms indicating the properties, their meaning and their measures are significant and understandable by non-expert designer people we carried out a survey. This paper describes the methodology adopted and the outcomes of this survey. Tue, 01 Jan 2013 00:00:00 GMT http://hdl.handle.net/10985/9002 2013-01-01T00:00:00Z GIANNINI, Franca MONTI, Marina PELLETIER, Jérôme PERNOT, Jean-Philippe World-wide market competition and the need to create products that better satisfy the market expectations require a more comprehensive involvement of the customer in the product definition loop. Therefore, it is crucial to provide customers with very easy-to-use shape definition and modification tools, allowing them to verify and evaluate possible shape alternatives without requiring specific knowledge on geometric modeling. A set of aesthetic properties guiding the shape characterization and appraisal have been identified together with measures for their evaluation and shape modeling methods for their direct modification. Since these properties have been indicated by stylists, no guarantee exists that they are usable in a context directly involving customers in the product definition loop. To verify the extent to which the terms indicating the properties, their meaning and their measures are significant and understandable by non-expert designer people we carried out a survey. This paper describes the methodology adopted and the outcomes of this survey. http://hdl.handle.net/10985/11345 Processing free form objects within a Product Development Process framework FALCIDIENO, Bianca; GIANNINI, Franca; LÉON, Jean-Claude; PERNOT, Jean-Philippe The purpose of the chapter is then to review: (1) the stages of a product development pro- cess (PDP) where free-form shapes appear and are subjected to aesthetic and functional require- ments; (2) the modeling, sketching, and modification activities illustrating how free-form surfaces can be processed and what are the corresponding difficulties faced during these tasks; (3) the con- tributions of our community to solve some of these issues, and the problems which are still open. Wed, 01 Jan 2014 00:00:00 GMT http://hdl.handle.net/10985/11345 2014-01-01T00:00:00Z FALCIDIENO, Bianca GIANNINI, Franca LÉON, Jean-Claude PERNOT, Jean-Philippe The purpose of the chapter is then to review: (1) the stages of a product development pro- cess (PDP) where free-form shapes appear and are subjected to aesthetic and functional require- ments; (2) the modeling, sketching, and modification activities illustrating how free-form surfaces can be processed and what are the corresponding difficulties faced during these tasks; (3) the con- tributions of our community to solve some of these issues, and the problems which are still open. http://hdl.handle.net/10985/11338 Incorporating free-form features in aesthetic and engineering product design: State-of-the-art report FALCIDIENO, Bianca; GIANNINI, Franca; LEON, Jean-Claude; PERNOT, Jean-Philippe The use of free-form shapes has become mainstream to design complex products that have to fulfil engineering requirements as well as aesthetic criteria. Even if today’s CAD systems can easily represent free-form shapes by means of NURBS surfaces, their definition and modification still require a deep knowledge and a great skill in the manipulation of the underlying mathematical models. The implemented free-form shapes design operators are time consuming and do not enable fast modifications. To overcome these limits, some researches have been undertaken to try to adapt the feature concept, successfully adopted for the design of regular shapes, in the free-form domain. It gives rise to a set of free-form features modelling strategies. This paper gathers together the state-of-the-art of these advances. The various approaches are depicted and compared with respect to a very precise set of criteria expressing the needs in aesthetic and engineering designs. The limits and future trends are presented Tue, 01 Jan 2008 00:00:00 GMT http://hdl.handle.net/10985/11338 2008-01-01T00:00:00Z FALCIDIENO, Bianca GIANNINI, Franca LEON, Jean-Claude PERNOT, Jean-Philippe The use of free-form shapes has become mainstream to design complex products that have to fulfil engineering requirements as well as aesthetic criteria. Even if today’s CAD systems can easily represent free-form shapes by means of NURBS surfaces, their definition and modification still require a deep knowledge and a great skill in the manipulation of the underlying mathematical models. The implemented free-form shapes design operators are time consuming and do not enable fast modifications. To overcome these limits, some researches have been undertaken to try to adapt the feature concept, successfully adopted for the design of regular shapes, in the free-form domain. It gives rise to a set of free-form features modelling strategies. This paper gathers together the state-of-the-art of these advances. The various approaches are depicted and compared with respect to a very precise set of criteria expressing the needs in aesthetic and engineering designs. The limits and future trends are presented http://hdl.handle.net/10985/11377 Aesthetic-oriented classification of 2D free-form curves PETROV, Aleksandar; GIANNINI, Franca; FALCIDIENO, Bianca; PERNOT, Jean-Philippe; VERON, Philippe Nowadays, it is commonly admitted that the aesthetic appearance of a product has an enhanced role in its commercial success. Therefore, understanding and manipulating the aesthetic properties of shapes in the early design phases has become a very important field of research. There exists an appropriate vocabulary for describing the aesthetic properties of 2D free-form curves that includes terms such as straightness, acceleration, convexity and tension, which are normally used by stylists when describing and modifying shapes. However, the relationships between this vocabulary and the geometric models are not well established. This work investigates the possibility of applying Machine Learning Techniques (MLT) to discover possible classification patterns of 2D free-form curves with respect to the so-called straightness of the curve. First, we verified that MLT can correctly (99.78%) reapply the classification to new curves. In addition, we verified the abilities of the Attribute Selection methods to identify the most important attributes for the considered classification, among a larger set of attributes. As a result, it was possible to recognize as the most characterizing parameters the same curve attributes previously used to compute the measure of straightness (S). Moreover, Linear Regression (LR) was able to extract automatically an exact mathematical model, which can correlate the geometric quantities with the class of the curve, congruent to one we previously specified. This work indeed demonstrates that MLT are very suitable and can be efficiently used in this context. The work is a first step towards the characterization and classification of free form surfaces giving the general directions on how MLT can be exploited to characterize free-form surfaces with respects to the aesthetic properties. Wed, 01 Jan 2014 00:00:00 GMT http://hdl.handle.net/10985/11377 2014-01-01T00:00:00Z PETROV, Aleksandar GIANNINI, Franca FALCIDIENO, Bianca PERNOT, Jean-Philippe VERON, Philippe Nowadays, it is commonly admitted that the aesthetic appearance of a product has an enhanced role in its commercial success. Therefore, understanding and manipulating the aesthetic properties of shapes in the early design phases has become a very important field of research. There exists an appropriate vocabulary for describing the aesthetic properties of 2D free-form curves that includes terms such as straightness, acceleration, convexity and tension, which are normally used by stylists when describing and modifying shapes. However, the relationships between this vocabulary and the geometric models are not well established. This work investigates the possibility of applying Machine Learning Techniques (MLT) to discover possible classification patterns of 2D free-form curves with respect to the so-called straightness of the curve. First, we verified that MLT can correctly (99.78%) reapply the classification to new curves. In addition, we verified the abilities of the Attribute Selection methods to identify the most important attributes for the considered classification, among a larger set of attributes. As a result, it was possible to recognize as the most characterizing parameters the same curve attributes previously used to compute the measure of straightness (S). Moreover, Linear Regression (LR) was able to extract automatically an exact mathematical model, which can correlate the geometric quantities with the class of the curve, congruent to one we previously specified. This work indeed demonstrates that MLT are very suitable and can be efficiently used in this context. The work is a first step towards the characterization and classification of free form surfaces giving the general directions on how MLT can be exploited to characterize free-form surfaces with respects to the aesthetic properties. http://hdl.handle.net/10985/11351 Categorization of CAD models based on thin part identification GIANNINI, Franca; PETTON, Cédric; PERNOT, Jean-Philippe Nowadays, industrial CAD models databases are becoming larger and larger, thus inaugurating new challenges for their management during the product design process. Unfortunately, neither the PDM nor PLM systems are good at indexing and sorting CAD models according to their content, and it is sometime more efficient to redesign a part than to try to find it in a database. Categorizing parts is a first step to solve this problem. This may allow both the re-use of the parts and the retrieval of the methods and pro- cesses adopted on them, thus avoiding wasting time restarting from scratch. In this paper, we focus on the characterization and classification of industrial parts with respect to the meshing issue, and notably the meshing of thin parts difficulty handled automati- cally and which often requires adaptation steps. The concepts of thin object and thin part are introduced together with the mechanisms and criteria used to identify such shape characteristics on CAD models. The final categorization results of a set of tests ex- ploiting a normalized distance distribution associat- ed to specific ratios computed from the bounding box surrounding the object to be classified. The proposed approach has been implemented and validated. Sun, 01 Jan 2012 00:00:00 GMT http://hdl.handle.net/10985/11351 2012-01-01T00:00:00Z GIANNINI, Franca PETTON, Cédric PERNOT, Jean-Philippe Nowadays, industrial CAD models databases are becoming larger and larger, thus inaugurating new challenges for their management during the product design process. Unfortunately, neither the PDM nor PLM systems are good at indexing and sorting CAD models according to their content, and it is sometime more efficient to redesign a part than to try to find it in a database. Categorizing parts is a first step to solve this problem. This may allow both the re-use of the parts and the retrieval of the methods and pro- cesses adopted on them, thus avoiding wasting time restarting from scratch. In this paper, we focus on the characterization and classification of industrial parts with respect to the meshing issue, and notably the meshing of thin parts difficulty handled automati- cally and which often requires adaptation steps. The concepts of thin object and thin part are introduced together with the mechanisms and criteria used to identify such shape characteristics on CAD models. The final categorization results of a set of tests ex- ploiting a normalized distance distribution associat- ed to specific ratios computed from the bounding box surrounding the object to be classified. The proposed approach has been implemented and validated. http://hdl.handle.net/10985/22962 User-Driven Computer-Assisted Reverse Engineering of Editable CAD Assembly Models SHAH GHAZANFAR, Ali; GIANNINI, Franca; MONTI, Marina; PERNOT, Jean-Philippe; POLETTE, Arnaud This paper introduces a novel reverse engineering (RE) technique for the reconstruction of editable computer-aided design (CAD) models of mechanical parts’ assemblies. The input is a point cloud of a mechanical parts’ assembly that has been acquired as a whole, i.e., without disassembling it prior to its digitization. The proposed framework allows for the reconstruction of the parametric CAD assembly model through a multi-step reconstruction and fitting approach. It is modular and it supports various exploitation scenarios depending on the available data and starting point. It also handles incomplete datasets. The reconstruction process starts from roughly sketched and parameterized CAD geometries (i.e., 2D sketches, 3D parts, or assemblies) that are then used as input of a simulated annealing-based fitting algorithm, which minimizes the deviation between the point cloud and the adapted geometries. The coherence of the CAD models is maintained by a CAD modeler that performs the geometries’ updates while guaranteeing the possibly imposed constraints and model coherence. The optimization process leverages a two-level filtering technique able to capture and manage the boundaries of the geometries inside the overall point cloud in order to allow local fitting and interfaces detection. It is a user-driven approach where the user decides what are the most suitable steps and sequence to operate. It has been tested and validated on both real scanned point clouds and as-scanned virtually generated point clouds incorporating several artifacts that would appear with real acquisition devices. Thu, 16 Dec 2021 00:00:00 GMT http://hdl.handle.net/10985/22962 2021-12-16T00:00:00Z SHAH GHAZANFAR, Ali GIANNINI, Franca MONTI, Marina PERNOT, Jean-Philippe POLETTE, Arnaud This paper introduces a novel reverse engineering (RE) technique for the reconstruction of editable computer-aided design (CAD) models of mechanical parts’ assemblies. The input is a point cloud of a mechanical parts’ assembly that has been acquired as a whole, i.e., without disassembling it prior to its digitization. The proposed framework allows for the reconstruction of the parametric CAD assembly model through a multi-step reconstruction and fitting approach. It is modular and it supports various exploitation scenarios depending on the available data and starting point. It also handles incomplete datasets. The reconstruction process starts from roughly sketched and parameterized CAD geometries (i.e., 2D sketches, 3D parts, or assemblies) that are then used as input of a simulated annealing-based fitting algorithm, which minimizes the deviation between the point cloud and the adapted geometries. The coherence of the CAD models is maintained by a CAD modeler that performs the geometries’ updates while guaranteeing the possibly imposed constraints and model coherence. The optimization process leverages a two-level filtering technique able to capture and manage the boundaries of the geometries inside the overall point cloud in order to allow local fitting and interfaces detection. It is a user-driven approach where the user decides what are the most suitable steps and sequence to operate. It has been tested and validated on both real scanned point clouds and as-scanned virtually generated point clouds incorporating several artifacts that would appear with real acquisition devices.