Research On Model State Generation Based On Error Analysis And Feature Displacement

3D computer aided design (CAD) system that using feature-based solid modeling technique has been widely used for product design recently. Meanwhile, CAE also plays a more and more important role in product design, in which finite element is one of the most popular methods. Models built by CAD systems usually need simplification before finite element analysis to meet analysis requirement. Multi-state model means diversified models formed by variation of features. The method and degree of simplification are two essential problems in model automatic transformation from CAD to CAE. To cut down computational complexity on the premise of a certain analysis precision, the measurement method of the error of models of different simplification level that emerge from displacing high curvature sweeping feature with polygonal line sweeping feature is proposed, multi-state models with different precision are gained. The main content includes:(1) Establish the overall framework of Multi-state theory; propose the conception of level of error in order to measure the level of feature simplification objectively, which stand for the error caused by its corresponding simplification way.(2) A method of displacing high curvature sweeping feature with polygonal line sweeping feature is proposed, by which multi-state models with different precision could be gained. It should be regarded as a new method of simplification except for feature remove, feature reduction and symmetrical simplification.(3) Use the difference between approximation error to measure the difference between two approximation method according to the theory of approximation, get the method of measuring the displacement error between finite element analysis results of pre and post model.(4) The conclusion that three error factors exist in feature displacement is drawn. They are measurement of mash variation domain, the variation of diameters of the meshing conditions caused by feature displacement and the changing trend of field function in the area around the feature.(5) Give the estimation method of three factors of displacement error. And further more, establish the multi-state model generation system based on error analysis and feature displacement.