Study On A Few Key Algorithms In The Rapid Inverse Forming Code For Auto Panels

The automobile is one of the significant products in China industrial development. China encourages the development of and research on the molding and die technology of auto bodies and parts, which effectively accelerates the advancing paces of our automotive industry . At present, however, our auto body dies mostly depend on import. The forming technics and die technology are the main difficulties in the development of our automotive industry. Only with the advanced auto body forming thecnics and die technology will we develop a sustainable , innovative and independent automotive industry.This paper conjunct with the project of the state's 95 key scientific and technological: "stamping molding simulation technology of automobile cover and CAD / CAE / CAM Integration System", and key projects of the National Natural Science Foundation "the theoretical foundation of Stamping Molding and die designing, calculation methods and key technical "issues, a preliminary step in the large number of key issues of forming coordinate conversion, finite element mesh optimization, solving the large-scale equations.First, the procedures of OpenGL has a application of a broad and has a wide range of broad transplantation, and therefore, has become the current standards of 3D graphics development. 3D graphics processing, display, and physical structures need to use three-dimensional geometric transformation, transform of graphics research has important theoretical value and actual value. This paper uses a combination of geometric transformation matrix derivation of the general transformation matrix form, and its derivation in OpenGL applications.Secondly, to get a precise forming result, we must ensure that the quality of grid. This paper examines the gradual improvement of one-step in the practical application. Quality of grid is very important in the solution process, but after extensive testing that, especially the model with complex structure, which will directly affect the stability of solving, how to get in line with the computing requirements of grid, that is the problem we have to resolve .The judgement of the unit of the strip problem, this paper introduces the radius ratio method, hat is, "inscribed circle radius r / circumcircle radius R", traversing the grid in all units, inspection unit's ratio r / R, according to this ratio we will determine whether the unit strips, when r / R ratio greater than 0.5, we think that this unit does not strip, when ratio r / R smaller, the units will be strip, the more amend for that course. Of course, we have also done a judge on the level of the strip of the unit, and that will be show in different colors. There are two options about modifying method: one is the "elimination of the smallest edge" and the other one is the "changing the longest edge", according to the specific circumstances of the units, we will choose different solutions.The judgement of the discount problem of the unit is based on correlation and cosine angle, through dialog unit of inspection, searching the unit and then to find the discount unit according to different parameters, and marking the unit belonging to a discount unit. Similarly, painting in different colors, show that: must-modified, attention to be paid and neglected. Before modify the unit, we should do a judgement on whether the discount unit is at the border, in both cases, that will be given different methods.The expectations of this chapter is to do the quality inspection and modifying of the grid which is generate in pre-process, now we achieve the automatically check of grid's quality, but still require manual amendment, for the automatical amendment, we need further research.Third, at present, increasing attention has been paid to a three-dimensional finite element technique on plastic machining process simulation. Direct method more stable, faster than Iterative Method, instead of the direct method with rapid compression storage is faster than the direct method, the characteristics of less memory occupied has collected the far-reaching attention. KMAS / one-step as a major CAE analysis software, speed and stability will inevitably become the objective of its pursuit. This chapter conduct research on the basic principles of MVSS for this issue and and in the one-step application of the simulation analysis, as well as compare with FASTFORM.This chapter research on this issue and study the basic principles of MVSS and its application in plastic processing large three-dimensional finite element simulation analysis:1. This chapter will put the traditional LDL~T, and PKU-MVSS together for tests with standard work-piece provided by UGS on PC. The main purpose of the test with MVSS (Amendment sparse vector method) is to testify the accuracy and the speed of solution.2. This chapter is about the selection of the plate which is in the works for solving practical problems for the highest occupied memory, use this as a case of full-scale tests will show solver for the memory limit for the status of the situation, the practical engineering problems are generally smaller than this. The results of analysis showed that the MVSS is very smooth and stable in solving plate problems .3. The chapter will apply MVSS for one-step, and compare with the traditional forming software Fastform . The result shows that the one-step advances in time and memory capacity.