Reverse Engineering Of Automobile Body Panels:Reconstruction And Fluent Simulation

The designing of car body is one of the key technologies in the complete vehicle development. Amount this, and the body panels are an important part of the car body.The panels,especially the panels of automobile body,have the shortest life circle,and they are most variable. And it is one of the most important factors to increase the automobiles competition ability.Because it not only has a direct impact on its external appearance and production costs as well as its development circle,but also can make it renovated more quickly,which are concerned about for consumers. Our country is automobile production and marketing power, but is still far behind the top car countries. Mainly the lack of capacity of independent research and design, including many aspects, the body is one important factor. Its crucial significance and role for enhancing the independent innovation capability, high efficiency and low cost of development,design and manufacture of automotive panels. If we can stand to study and research on the shoulders of giants.The reverse engineering is a process of rebuilding digital model according to the physical data, including data acquisition,data preprocessing,data block and surface reconstruction and other sectors,which is a fast,high-quality,efficient modern design.Computational fluid dynamics(CFD) simulation,in recent years, with the development of computer technology and the widespread attention and application.has the advantages of less time,less cost,no actual car models,which has a positive effect in the development and improvement of automotive products. The Combination of reverse engineering and CFD can shorten designing cycle of automobile and absorbadvance existent technology,reduce development costs, improve design efficiency and quality,which has a certain engineering significance and practical value to car and other manufacturing enterprises. This work includes the following aspects:(1)Reverse Engineering Theory is introducted. According to this theory,body point cloud is obtained by the laser scanner,and after the optimizations of removing noise,multi-view combination,data reduction and other processes, the triangular mesh is utilized to the establishment of topological relations between points,then the hole patching,sanding uneven department of wrinkles and other operations is used to obtain a smooth triangular flat sheet;(2)A quadrilateral domain surface reconstruction method based on triangle plane slice extraction of vehicle body feature line and boundary line is proposed. This method is not obtaining feature points in the massive point cloud data,but extract feature lines on a triangular plane,Based on the obtained characteristic lines and boundary lines,the body is divided into several large surface panels to reconstruct the entire surface body panels.(3) A brief description of the relevant theoretical knowledge of aerodynamics.According to the general simulation process: Firstly, Hypermesh divided surface mesh; Secondly,volume mesh using ICEM divided on the basis of the surface mesh;Lastly,tetrahedral+prism hybrid mesh program was used to build the finite element mode,the whole couple surrounded by density body to define the grid surface area.(4)Realizable turbulence model,second-order upwind discretization,SIMPLE algorithm for pressure- velocity coupling are used,we obtains body surface pressure distribution and the velocity vector.(5)Through the analysis of vehicle's air surface speed and pressure characteristics,we can understand the laws and situations for air movement and make suggestions to improve automotive body design. On the recommendation of the optimal design, and improved model simulation verify the reasonableness of the proposal.