A Digital Twin-Oriented Lightweight Approach for 3D Assemblies

In the design and operation scenarios driven by Digital Twins, large computer-aided design (CAD) models of production line equipment can limit the real-time performance and fidelity of the interaction between digital and physical entities. Digital CAD models often consist of combined parts with characteristics of discrete folded corner planes. CAD models simplified to a lower resolution by current mainstream mesh simplification algorithms might suffer from significant feature loss and mesh breakage, and the interfaces between the different parts cannot be well identified and simplified. A lightweight approach for common CAD assembly models of Digital Twins is proposed. Based on quadric error metrics, constraints of discrete folded corner plane characteristics of Digital Twin CAD models are added. The triangular regularity in the neighborhood of the contraction target vertices is used as the penalty function, and edge contraction is performed based on the cost. Finally, a segmentation algorithm is employed to identify and remove the interfaces between the two CAD assembly models. The proposed approach is verified through common stereoscopic warehouse, robot base, and shelf models. In addition, a scenario of a smart phone production line is applied. The experimental results indicate that the geometric error of the simplified mesh is reduced, the frame rate is improved, and the integrity of the geometric features and triangular facets is effectively preserved.

Influence of the height of the ribbed-ring dome on the stress state of its frame during the overhang mounting process

The aim of the research. To analyze the stress state of structures of ribbed-ring domes of different heights during overhang erection. The domes have spherical metal frames and a support contour of the same diameter. Due to different heights, the steepness of the geometric shape of the domes changes. The study is devoted to establishing the relationship between the stress state of the frame and the steepness of the dome when mounted. It was investigated how the height of the ribbed-ring dome affects the stress state of its frame during overhang mounting process. Methods. Computer models of design frames of ribbed-ring domes of different heights made of steel I-beams were developed. Based on design models, a sequence of assembly models for incomplete frames was created for different stages of installation. Both for the design and for all installation models of dome frames of different heights, computer calculations were performed for the effect of the load from its own weight. As a result of calculations for all domes and at all stages of installation, deformations and stresses in the meridional ribs were determined, which were compared with the design diagrams. Results. Comparative graphs of deformations of dome frames and diagrams of changes in the degree of use of steel strength in meridional ribs at all stages of mounted installation are obtained. Comparative graphs of installation and design stresses in the meridional ribs on different tiers for all stages of mounted installation are also shown. The assessment of the installation stress states is given, their inevitability and the degree of influence on the stress state of the dome frames are noted.

DEVELOPMENT OF STANDALONE SOFTWARE SOLUTIONS BASED ON GEOMETRIC KERNELS FOR CREATING DIGITAL ASSEMBLY MODELS OF MACHINE TOOLS

The article discusses approaches and solutions aimed at increasing the productivity of engineering departments, where CAD software solutions are actively used. In the manufacture of machine parts, it becomes necessary to design technological equipment. Elements of machine tools can be prepared and placed in electronic catalogs (libraries), which in an automated mode will create a set of parametric models of the required technological equipment of machine tools. In this case, the accuracy and quality of modeling will be achieved by excluding the human factor from the design process. The development of such software solutions is implemented by means and components of the open geometric kernel Open Cascade, which has great potential both in the field of modeling and scientific computing.