Modularization Development Of Pre-and Post-Processors Of CAE Software KMAS For Sheet Forming Based On COM

The ability of the independent development new automotive style is a basic mark during the methods of evaluating the automotive industry, especially the car industry. It takes not only a long time to design, manufacture, and try-out the stamping die, but also a vast investment for the stamping die during the whole cycle from the new automotive style development to production. The application of Computer Aided Engineering (CAE) technique to the sheet metal forming process, by the quantitative numerical simulation, we can optimize the die structure and the design of die surface, shorten the try-out time cycle, reduces the cost of the automotive and increases the market competence of the product before manufacture the die.This paper took a in-depth research on the key algorithm of pre- and postprocessors in KMAS which is a sheet metal forming CAE software,the mechanism theory of springback in high strength steel forming,the measure of spring-back control and die compensation during high strength steel bending, and develop the pre- and post processors system in KMAS based on COM component.COM (Component Object Model) component is a communication standard designed by Microsoft corp. to solve the reusability in different programms, and the component object can achieve the communications with each other in binary structure. COM component likes a kind of "toy bricks" which can achieve some functions, by the communication between the interface and client software, the development based on COM component is to build the customer required software by some components, it is a fast and optional development method.The model operation on pre- and post- processors takes a mass of work during the CAE of the car panel forming, so pre- and post-processors systems take an important role in KMAS system, and the main function of them is to establish the FEM mesh model and the relatived data input. The chapter 3 expatiate on the algorithm to check FEM element geometry shape,the algorithm to check adjacent element angle,the algorithm on consistent of element normal etc. according to the require of the key functions such as FEM mesh quality,mesh refine,generate tools mesh.> Algorithm to check FEM element geometry shapeIt used to find out the abnormality shaped element information in the mesh model, in the algorithm either the ratio between the mimmum length and the maximum length in the element is smaller than the given permissible value, or any an internal angle in the element is bigger than the given maximum permissible one or smaller than the minimum permissible one, then this element is abnormality and store the element information.> Algorithm to check adjacent element angleThis is a rule to judge whether it's necessary to refine FEM mesh, when the angle between the borders on elements is smaller than the given angle, label it. When contact judge between blank and tools, if the blank element contact with the marked tool element, then refine the blank element. The angle is known by calculating the the supplementary angle of the angle between two element normal, then judge it, if abnormality, then store the element information.> Algorithm on consistent of element normalAll element normal must have a consistent direction, because the tools generated by the FEM mesh offset require the mesh normal consistent. But in the reality, the normal of element which generated by mesh generator is not consistent. Because of this, imbibing the strongpoint from "reference direction method" and "reference element method", the author put forward an efficient method "seed element method". Firstly, find out the seed elements according to consistent rule about the element normal and forming direction, if the normal is not consistent when doing the expand searching cycle in the elements around the seed elements, then auto reverse the element normal. The algorithm has a high accuracy and efficiency compared with the other two algorithms.The pre-processor user interface framework adopt the Microsoft's window frame template library WTL which is supported COM component, and it can solve to the problem of MFC takes an excessive resource well. According the above mentioned algorithm, establish relevant COM components, and integrate it to the pre-processor in KMAS system, it gain the anticipative effect in the testing result.The main function of the post processor in KMAS is to display the model simulation result and quality evaluation. The display adopts the OpenGL Graphics processing kernel library. Aim at the physics value discrete display in the post processor, the author put forward a more effective node physics quantity display grade algorithm, to calculating node physics value grade. The physics value of the node subtract the minimum value of the node physics value, then divide the average interval value of physics quantity series, then to the nearest integer, and according to the position of node that whether to add 1 to modify the node grade, at last fill draw the element based on the color corresponding to the grade by the plot function in the OpenGL. As to the physics value continuum display contour in post processor, after get the element color, it carried out by the auto color smooth transition of OpenGL polygon fill plot function, the display effect is excellent, up to the level of KMAS required.In order to check the result of the forming simulation in post processor in KMAS, the FLD grade algorithm was developed. According to the FLC to estimate the forming result, including low stretch,safe,trend split,split,trend wrinkle,and wrinkle, caculate the location where the part node strain is. Then filled element model by the color related to the field in continuum display, and plot the FLC chart in a child window, display the node strain position in the FLC, this can help user to judge the part deform degree.With the application of light metal alloy in automotive lightweight design, the research has been focus to the spring-back control and compensation measure of high strength steel and aluminum alloy. In chapter 6, the BENCHMARK presented at the NUMISHEET 2002 conference was sdutied base on KMAS, the mechanism theory of spring-back in high strength steel forming was discussed, the accurate and reliable of spring-back prediction were validated. Further put forward CAD/CAE/CAM flow chart for controlling springback and die compensation based on KMAS, some compensation measure was presented for typical bending structure; modified die design for a truck beam, result indicate that the die compensation measure base on KMAS is efficacious.