Generation of consistent skin model shape based on FEA method

Controlling product geometric quality is an important issue, because real parts deviate from their nominal value (e.g., in form, orientation, and position error of features, size of part, etc.). To analyze the influence of these deviations on final product, one solution is to consider the nonnominal Skin Model Shape to simulate assembly, manufacturing, or metrology. The modeling of nonnominal parts is still in its initial phases. First, methods of generating a single feature with deviations are reviewed and classified. With the combination of the single nonideal features to obtain the complete nonideal model of the part, geometrical issues appear, such as gaps and self-intersections. These can be influenced by acute and obtuse angles and the ratio between mesh size and deviation value. From an analysis of these issues, two deviation combination methods are proposed to preserve the manufacturing deviation of features and consistency of the model. These methods are qualified as local and global methods. The local method is based on the iterative calculation of mesh regularization. The global method is based on finite element analysis, with manufacturing deviations added to the nominal model by the penalty function approach. The effectiveness and efficiency of both kinds of method are compared on a trial geometry. The global method is preferred as it needs no iterative calculation, no stop criteria and gives better results. Finally, the proposed method is validated on a more complex mechanical part: a cutter body.