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Currently, the product development process being collaborative and distributed, it relies on multiple skills and representations of the product. Obtaining the digital representation of the product model required for each product view is time consuming because component shapes and their associated data need to be adapted. In this part 1 paper, an analysis of the requirements for this shape adaptation process is performed that leads to the concepts and organization of the so-called mixed shape representation. Here, we show how BRep NURBS CAD models and polyhedral models combined with the concept of High Level Topology introduced enable the explicit and intrinsic description of the concepts needed to efficiently transform shapes between product views. A set of operators briefly outlined illustrates the effect of the proposed approach on the possibilities of shape

The preparation of simulation models from Computer Aided Design (CAD) models is still a difficult task since shape changes are often required to adapt a component or a mechanical system to the hypotheses and specifications of the simulation model. Detail removal or idealization operations are among the current treatments performed during the preparation of simulation models. Most of the time, model exchanges are required between the engineering office and the simulation engineers, often producing losses of information and lacking of robustness. Thus, inefficient processes and remodelling phases form the usual practice. In this paper we show that geometric models can be extracted from CAD software as well as some of their semantics. This semantics can then be transferred, used and eventually preserved during the shape adaptation process required for a given Finite Element Analysis (FEA). The software environment enabling this transfer simultaneously requires the description of the initial B-Rep NURBS model as well as that of the adapted one. The process set up is based on STandard for the Exchange of Product model data (STEP) to provide a robust link between CAD and shape adaptation environments. In order to describe the appropriate variety of shapes required for the Finite Element (FE) preparation, a specific data structure is proposed to express the corresponding topology of the models. Hence, it is shown that the operators associated to the FE preparation process can take advantage of this data structure and the semantics of the initial CAD model that can be attached to the adapted model. Examples illustrating the various process steps and corresponding operations are provided and demonstrate the robustness of the approach.

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International audienceComputer Aided Design (CAD) and Computer Aided Engineering (CAE) are two significantly different disciplines, and hence they require different shape models representations. As a result, models generated by CAD systems often need to be submitted to shape transformations for Finite Element Analysis (FEA). In this paper, a new approach is proposed to ease integration between CAD and CAE also outlining some patents. It is based on new shape representation called 'mixed shape representation' that supports simultaneously a B-Rep (manifold and non-manifold) and a polyhedral representation to create a robust link between the CAD and CAE environments. Both representations are maintained through the same topology description called the High Level Topology (HLT), which represents a common requirement for simulation model preparation. An innovative approach to FE model preparation based on the mixed representation is presented in this paper. Thus a set of necessary tools is associated to the mixed shape representation, which contributes to reduce, as much as possible, the time of a model preparation process