A general mathematic model framework for assembly process driven digital twin of assembly precision

In precision mechanical machinery, integrating geometric measurements with virtual models to create a digital twin of assembly precision is a key development trend for enhancing assembly accuracy. However, current assembly geometry evaluations are mainly focused on target functional requirements and are insufficient to represent the dynamic geometry of the product during the assembly process, which is crucial for a digital twin. In this context, this paper presents a general mathematical model framework for a digital twin of assembly geometry precision, driven by the assembly process. The framework includes two key aspects. The first aspect is an integrated coordinate system for evaluating assembly geometry precision. This system consists of multi-layer assembly objects, feature assembly defects, and assembly deviations. The second aspect is a two-step assembly deviation propagation and update calculation framework driven by single-step assembly operations. This framework supports the integration of various deviation propagation methods for joint surfaces and provides dynamic updates of the assembly geometry for the as-built product. The assembly of a high-pressure compressor rotor demonstrates that the developed digital twin model of assembly geometry precision dynamically updates as the assembly progresses, incorporating measurement data. This model can be delivered as a digital instance of assembly geometric precision along with the product. It is anticipated to provide digital tool support for the precision twinning of complex product assemblies, fostering advancements in assembly precision modeling and optimization.