Research On Virtual Assembly Simulation System For Shaped Thin Parts

With the rapid development of aerospace,thin-walled parts with light weight and good performance are widely used.However,due to the large size,complex structure and easy deformation of the thin-walled parts,the difficulty in the assembly process is increased.Especially for some heat-resistant structural shell parts,since the inner shell is made of a metal material and the outer shell is made of a non-metallic material,the outer shell and the inner shell will not only affect the assembly precision due to deformation and machining errors during the assembly and affect part safety due to interference and so on.Therefore,this article focuses on the problems in the assembly process of shaped thin-walled parts,researching on virtual assembly simulation system for shaped thin-walled parts,including the research on the data acquisition and processing methods,surface reconstruction methods and virtual assembly methods,then achieved the development of assembly simulation software.The corresponding research methods and virtual simulation software are experimentally verified through the test pieces.The research of the thesis has important theoretical significance and practical application value.The specific research contents are as follows:(1)Study to determine the overall design program of the virtual simulation system for shaped thin-walled components.The assembly principle and the actual assembly requirements of the special-shaped thin-walled parts are analyzed,the assembly process flow is formulated,the overall design scheme of the virtual assembly simulation system is determined according to the assembly process flow,and the system mainly includes the data acquisition and processing method module,the surface reconstruction method module and the virtual Assembly method module.(2)To carry out research on surface data acquisition and processing of shaped thin-walled parts.By analyzing the advantages and disadvantages of contact measurement and non-contact measurement,the method of data acquisition is determined according to the characteristics of the workpiece structure,the items needing attention of the data acquisition path are put forward,and the data storage format and data acquisition software are determined.Point cloud data processing methods for point cloud is determined including point cloud alignment,point cloud denoising and point cloud streamlining according analysising the collected point cloud data characteristics,and the corresponding data processing algorithms are described.(3)To carry out research on the surface reconstruction of shaped thin-walled parts.Firstly,three mathematical models of Bezier,uniform B-spline and non-uniform B-spline are compared and analyzed,and the corresponding curve and surface reconstruction method is determined according to the geometric structure of the shaped thin-walled part.In this paper,the method of slice processing in curve reconstruction is studied deeply,the method of reconstruction of non-uniform B-spline mathematical model is studied,the curve curvature and continuity of the reconstructed curve are studied,and finally several surface reconstruction methods According to the characteristics of the workpiece,determine the surface reconstruction method.(4)To carry out research on the virtual assembly method of shaped thin-walled components.Analyzing and determining the assembly method of the virtual assembly,defining the expression method of the model in the virtual assembly environment,proposing the pose adjustment algorithm of the model in the assembly;According to the interference and gap analysis,the paper proposed to use CATIA DMU spatial analysis tools to achieve gap quantitative analysis and qualitative analysis of shaped thin-walled sets of interference.(5)Development and experimental verification of the virtual assembly simulation software for shaped thin-walled components.Through comparative analysis,the development environment of virtual assembly simulation system is determined,each function module of virtual assembly simulation system software is designed,and the methods of data acquisition and processing module development,surface reconstruction module development and virtual assembly module development are studied in depth.The interface of the virtual assembly simulation software was developed.According to the experimental pieces in this paper,the structure characteristics of the simulation assembly were analyzed.The functions of data acquisition and processing module,surface reconstruction module and virtual assembly module in the virtual simulation system were verified.The experimental results show that the system scheme determined in this paper is feasible.The developed virtual assembly simulation software system for thin-wall parts meets the actual engineering needs.