Application Research Of Ultrasonic C-scan 3D Imaging Technology For Aeroengine Blades

With the development and improvement of the computer technology,the point cloud data obtained by the scanning device is increasing,and the data structure of points cloud is becoming more and more complex.Reconstructing the original model of the sampling point quickly and accurately according to the type of data used has always been the goal pursued by reverse engineering.In this thesis,the aero-engine blade ultrasonic C-scan cloud is taken as the research object.The processing scheme for the single-layer C-scan cloud is developed based on the theoretical analysis of the three-dimensional reconstruction algorithm of Poisson equation,and the ultrasonic imaging detection based on the Poisson equation three-dimensional reconstruction algorithm is realized.The main contents of this thesis are as follows:(1)The three-dimensional reconstruction algorithm based on Poisson equation is studied.The advantages and disadvantages of existing solutions are analyzed for the boundarylessness of reconstruction results.A solution for the experimental data of this paper was developed according to the acquisition method and data characteristics of 3D ultrasound.(2)A directed point cloud boundary extraction method is proposed.In this paper,through the analysis and comparison of several common methods of feature boundary extraction of point clouds,the general method of simplifying the calculation process is found.Combined with the radius neighbor search method based on Morton code,a boundary feature extraction method based on boundary point characteristics is proposed.The method obtains a specific boundary point through the minimum bounding box,and then formulates a specific search route according to the mutual relationship of the boundary points,which reduces the unnecessary searching of the nearest neighbors of the internal points,and speeds up the search speed.(3)A simplified algorithm for point cloud vector estimation is proposed,and the application of 3D reconstruction algorithm based on Poisson equation in ultrasonic imaging detection is realized.By summarizing the main ideas of other algorithms,combined with the characteristics of the ultrasonic C-scan cloud,for the normal vector and position information of the filled point,the weight function based on the point cloud Euclidean distance is used on the spatial plane to estimate the initial normal vector of the point cloud,and then the normal direction of point cloud is corrected by MLS method,and the Poisson surface reconstruction of the ultrasonic C-scan cloud is finally completed,the application of the three-dimensional reconstruction algorithm based on Poisson equation in ultrasonic imaging detection is finally realized combined with the intensity value information of the ultrasonic point cloud.