Methodology for automatic recovering of 3D partitions from unstitched faces of non-manifold CAD models

Data exchanges between different software are currently used in industry to speed up the preparation of digital prototypes for Finite Element Analysis (FEA). Unfortunately, due to data loss, the yield of the transfer of manifold models rarely reaches 1. In the case of non-manifold models, the transfer results are even less satisfactory. This is particularly true for partitioned 3D models: during the data transfer based on the well-known exchange formats, all 3D partitions are generally lost. Partitions are mainly used for preparing mesh models required for advanced FEA: mapped meshing, material separation, definition of specific boundary conditions, etc. This paper sets up a methodology to automatically recover 3D partitions from exported non-manifold CAD models in order to increase the yield of the data exchange. Our fully automatic approach is based on three steps. First, starting from a set of potentially disconnected faces, the CAD model is stitched. Then, the shells used to create the 3D partitions are recovered using an iterative propagation strategy which starts from the so-called manifold vertices. Finally, using the identified closed shells, the 3D partitions can be reconstructed. The proposed methodology has been validated on academic as well as industrial examples.This work has been carried out under a research contract between the Research and Development Direction of the EDF Group and the Arts et Métiers ParisTech Aix-en-Provence

Using polyhedral models to automatically sketch idealized geometry for structural analysis

Simplification of polyhedral models, which may incorporate large numbers of faces and nodes, is often required to reduce their amount of data, to allow their efficient manipulation, and to speed up computation. Such a simplification process must be adapted to the use of the resulting polyhedral model. Several applications require simplified shapes which have the same topology as the original model (e.g. reverse engineering, medical applications, etc.). Nevertheless, in the fields of structural analysis and computer visualization, for example, several adaptations and idealizations of the initial geometry are often necessary. To this end, within this paper a new approach is proposed to simplify an initial manifold or non-manifold polyhedral model with respect to bounded errors specified by the user, or set up, for example, from a preliminary F.E. analysis. The topological changes which may occur during a simplification because of the bounded error (or tolerance) values specified are performed using specific curvature and topological criteria and operators. Moreover, topological changes, whether or not they kept the manifold of the object, are managed simultaneously with the geometric operations of the simplification process

A Simulation Model for Logical and Operative Clash Detection

The introduction of the Building Information Modeling (BIM) approach has facilitated the management process of documents produced by different kinds of professionals involved in the design and/or renovation of a building, through identification and subsequent management of geometrical interferences (Clash Detection). The methodology of this research proposes a tool to support Clash Detection, introducing the logical-operative dimension, that may occur with the presence of a construction site within a hospital structure, through the integration of a BIM model within a Game Engine environment, to preserve the continuity of daily hospital activities and trying to reduce negative impacts, times and costs due to construction activities

A consistent interface element formulation for geometrical and material nonlinearities

Decohesion undergoing large displacements takes place in a wide range of applications. In these problems, interface element formulations for large displacements should be used to accurately deal with coupled material and geometrical nonlinearities. The present work proposes a consistent derivation of a new interface element for large deformation analyses. The resulting compact derivation leads to a operational formulation that enables the accommodation of any order of kinematic interpolation and constitutive behavior of the interface. The derived interface element has been implemented into the finite element codes FEAP and ABAQUS by means of user-defined routines. The interplay between geometrical and material nonlinearities is investigated by considering two different constitutive models for the interface (tension cut-off and polynomial cohesive zone models) and small or finite deformation for the continuum. Numerical examples are proposed to assess the mesh independency of the new interface element and to demonstrate the robustness of the formulation. A comparison with experimental results for peeling confirms the predictive capabilities of the formulation.Comment: 14 pages, 11 figure

Geometrical Product Specification and Verification as toolbox to meet up-to-date technical requirements

The ISO standards for the Geometrical Product Specification and Verification (GPS) define an internationally uniform description language, that allows expressing unambiguously and completely all requirements for the geometry of a product with the corresponding requirements for the inspection process in technical drawings, taking into account current possibilities of measurement and testing technology. The practice shows that the university curricula of the mechanical engineering faculties often include only limited classes on the GPS, mostly as part of curriculum of subjects like Metrology or Fundamentals of Machine Design. This does not allow students to gain enough knowledge on the subject. Currently there is no coherent EU-wide provision for vocational training (VET) in this area. Consortium, members of which are the authors of this paper, is preparing a proposal of an EU project aiming to develop appropriate course

Automating Robot Planning Using Product and Manufacturing Information

AbstractAdvances in sensing, modeling, and control have made it possible to increase the accuracy of robots, and enable them to perform in dynamic environments. Often, performance deficiencies are not evident until late in the development of the manufacturing process, which delays the beginning of production and may cause damage to parts that have already undergone costly manufacturing steps. The goal of this research is to determine if a robot can meet manufacturing requirements, how to optimally plan robot activities, and to monitor robot processes to track performance. To achieve this, representations of product and manufacturing information and robot capabilities should be carried through the design, process planning, production, and analysis phases. Standards for the exchange of this information have been developed, such as ISO 10303 Part 242 for semantic product and manufacturing information and device kinematics, and the Robot Operating System Industrial specification for robot modeling, path planning, and execution. This paper surveys the relevant technologies and standards needed to enable automated deployment of robots in new application areas

Effect Of The Error Propagation Rates In Developing A Skin Model Of Measured Surfaces In Coordinate Metrology

Coordinate metrology is the most commonly used inspection method to analyze surfaces for manufacturing errors and imperfections. The computational in today’s coordinate metrology are composed of a series of extensive computational tasks. Developing a triangulated skin model using a finite element method is an approach to construct a surface based on the discrete measured points, which can be used for integrated computational algorithms reducing the uncertainty of the inspection process. Reducing the errors in developing the skin model by calibrating the two main parameters of the algorithm, which specify the propagation of the geometric deviations in two orthogonal directions, is the objective in this work. By varying theses propagation parameters and tracking the overall error of the constructed skin model, their effects are evaluated. Various cases are studied and the resulting patterns of the errors for different surfaces are used to make suggestions on selection of the two parameters resulting accurate construction of the skin model of the measured work pieces based on the coordinate metrology data. This will provide a reliable technique to develop the skin model of the manufactured products for quality control, manufacturing process control, or repair and finishing of the products