Keywords: CAD-CAE integration, assembly simulation, digital mock-up.

The ability to automate the pre-processing of existing digital mock-ups (DMUs) becomes mandatory to simulate the structural behavior of product sub-assemblies. Currently, this challenge leads to the very tedious tasks of model preparation and transformations of DMUs available from CAD software. As a result of the large amount of interactive operations to prepare complex assemblies, some simulations are even not addressed.

This paper analyses the simulation assembly model preparation and proposes a structured methodology. It outlines the differences between tasks required to pre-process a single component for simulation and the tasks required to process a whole assembly composed of dozens to thousands of components. For assemblies composed of a few components, the process is mastered by users but still based on interactive low level actions. In the case of "medium" or "large" assemblies, this manual procedure could not be applied. The current state of the art shows that neither methodologies [1] nor automated data processing [2] are available to address the complexity of assembly preparation processes, particularly when idealizations are necessary.

To this end, the paper analyses the content of a DMU to explain why some information on interfaces between components is missing in DMUs but required to process geometric transformations. It shows how to derive the shape idealisation of industrial assembly models, resulting in categories of DMU transformations. This analysis has identified the lack of functional information in DMUs to cope with geometric transformations appearing in repetitive configurations observed in large assembly models. Functional information extraction, as the method conducted by Shahwan [3], can be an efficient enrichment of a DMU to identify and process repetitive configurations. The extraction of functional data from the initial DMU through a bottom-up method demonstrates its efficiency in characterising functional interfaces in a mechanical assembly. Finally, the analysis of shape transformations between components' applied to assemblies has revealed specific dependences between categories of shape transformations related to simulation objectives and user-specified hypotheses. These dependencies are structured and form the basis of a methodology to pre-process large assembly simulation models. This methodology will be the basis of automated assembly idealization processes.

1

J. Badin, D. Monticolo, D. Chamoret, S. Gomes, "Knowledge Configuration Management for product Design and Numerical Simulation", Int. Conf. on Engineering Design, ICED11, 15-18 August, Technical University of Denmark, 2011.

2

T.T. Robinson, C.G. Armstrong, R. Fairey, "Automated mixed dimensional modelling from 2D and 3D CAD models", Finite Elements in Analysis and Design, 47(2), 151-165, 2011. doi:10.1016/j.finel.2010.08.010

3

A. Shahwan, G. Foucault, J.-C. Léon, L. Fine, "Reasoning about functional properties of components based on geometrical descriptions", submitted to the Int. Conf. TMCE 2012.

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