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In the design step, the realistic modeling of the product represents an industrial requirement and a digital muck up (DMU) improvement. Thus, the tolerance integration in the computer aided design (CAD) model with the neglect of important physical factors, such as the components’ deformations during the mounting and assembly operation, causes a deviation between the numerical and the realistic models. In this regard, this paper presents a new model for the tolerance analysis of CAD assemblies based on the consideration of both manufacturing defects and deformations. The dimensional and geometrical tolerances are considered by the determination of assemblies’ configurations with defects based on the worst case tolerancing. The finite elements (FEs) simulation is realized with realistic models. An algorithm for updating the realistic mating constraints, between rigid and nonrigid parts, is developed. The case study of an assembly with planar and cylindrical joints is presented.

Nowadays, the tolerancing integration in CAD tools remains among the major goals of mechanical manufacturers. In the virtual product development, ideal and rigid models are used in the Digital Mock-up (DMU). Hence, research works developed integrated CAD models for tolerance analysis, while considering manufacturing defects. However, the tolerance analysis in the case of composite positional tolerance for feature patterns, commonly used in the industry, becomes a difficult activity with the consideration of parts deformations. Thus, this paper presents a novel CAD model for the tolerance analysis considering composite positional defect of features set and nonrigid component deformations due to external mechanical loads. The modeling of rigid components with dimensional defects is established based on the numerical perturbation method. Indeed, the relationships between driving and driven dimensions are determined to obtain the configurations in maximum and least material of the CAD model. Thereafter, the geometrical deviations are modeled by face displacements. The modeling of composite positional errors is performed while respecting the feature relating position tolerance zone framework and the pattern location tolerance zone framework constraints, as well as the maximum or least material condition. The deviations caused by nonrigid part deformations are considered by the integration of FE results into CAD model. The realistic configurations of the assembly are obtained after the updating of mating constraints between rigid and nonrigid parts with defects. The composite positional tolerance is analyzed with the simulation of relative motion between parts. A case study is proposed to evaluate the developed tolerancing method.

During the design stage, the ideal simulation and visualization of the mechanical assemblies behavior require the modeling of parts with dimensional and geometrical defects. However, the deviations caused by parts deformations can generate an important difference between the ideal assembly and the real product. In this regard, this paper proposes a tolerance analysis method of CAD assemblies considering non-rigid joints between parts with defects. The determination of realistic rigid components with dimensional and geometrical defects is based on the worst case tolerancing approach and the Small Displacement Torsor (SDT) parameters. The Finite Element (FE) computation is executed to determine deformations of realistic non-rigid part models under external loads. Sub-algorithms to define non-rigid joints between realistic parts are developed. The tolerance analysis is established using the realistic CAD assembly. A case study is presented to evaluate the proposed model.

Product assemblability and functional behavior are affected by geometric deviations. These deviations consist of manufacturing errors and part deformation defects caused by external loads. Taking the sources of deviations into account in tolerancing enable more precise results. In this context, the modeling of assembly parts with defects in a Digital MockUp is quite promising. In this paper, a decision support tool is proposed to consider multiple defects, such as tolerances and deformations of parts, in tolerance analysis. The worst-case concept and the Small Displacement Torsor are used to model rigid parts with orientation and positional defects. To model the part with form defects, the toleranced face is discretized into a grid of points. Random positions of the above points inside the tolerance zone are determined using the Gaussian Perturbation Method. A CAD method based on the B-spline interpolation allows the reconstruction of surfaces of rigid parts with form defects. Realistic configurations of non-rigid components are determined using the Finite Element Analysis. Sub-algorithms are developed to extract the realistic features of non-rigid parts. The realistic assembly configurations are performed by updating the mating constraints between realistic parts. In fact, automated sub-algorithms are used to redefine the part joints, while respecting the Objective Function of the Assembly. This paper proposes a novel method to consider all tolerance types on CAD models and part deformations. The tolerance analysis is performed to check the compliance with the Functional Requirement and to correct the initial tolerance values.

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