The Essential Algorithm And Component Development Of KMAS/One-step Pre-processor System For CAE Simulation Software Used By The Sheet Forming

Currently, China`s automobile industry has gradually incorporated into the world automobile industry system in many aspects, such as manufacture, research and development, sales services, automobile credit etc. It accelerates the development of China`s automobile industry and makes China become one of the major manufacturing bases. The ability of the developing independently new automotive style is a basic mark during the methods of evaluating the automotive 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 is applied to the panel stamping forming process and we can optimize the die structure and the design of die surface. This way is so true to nature that it can shorten the try-out time cycle, reduce the cost of the automotive and increase the market competence of the product before manufacturing the die by the quantitative numerical simulation.This paper takes a in-depth research on the key algorithm of pre- processors in KMAS which is a panel stamping forming CAE software(The formed modular surface fast equal-space, The background grid, The equal-space examination algorithm etc), optimizing the pre- processors system in KMAS/One-step based on COM component. COM (Component Object Model) component is an alternating standard design by Microsoft corp for solving the reusability between different programs, and the component object can achieve the interaction with each other in binary structure. COM component likes a kind of"toy bricks"which can achieve some functions by the interaction between the interface and client software. The development based on COM component is to build the software system performing the specialized design functions required by the customers form some existing components, and it is a fast and optional software development methodology.In the CAE simulation for the panel stamping forming process, the tool grid in the CAE software which input from the CAD software usually is only a modular surface through the grid pattern, either die surface, either punch surface. But, in the actual stamping forming process, it is often need to have the punch, the die, the blank-holder and the panel simultaneously. This requests to use the equal-space (Offset) algorithm for obtaining other modular surfaces directly from input a modular surface data before carrying on the CAE analysis. On the foundation of summarizing the predecessor`s experience and the insufficient, this article proposes an highly effective, fast forming modular surface equal-space algorithm based on finite element grid, of which most main core is the normal uniform algorithm– the seed unit method.Formed modular surface in the automobile cover is complex. To guarantee computed result's correctness around equal-space based on finite element grid, the formed modular surface's finite element grid should satisfy the following several conditions:1) The equal-space grid is continual, namely the grid should not have the slit or border flaws and exist the repetitive units, the redundant nodes, the free nodes.2) The equal-space grid's normal is consistent. namely facing a direction to each tool's all unit normal: either aiming at inside (die), either aiming at outside (punch).3) It is necessary to judge the grid equal-space rationality before the equal-space. Otherwise, it is possibility to appear the intersection phenomenon in the local region after grid equal-space. This kind of grids cannot be carried on the finite element computation, needing to return to the CAD software for modeling again.The seniors have made the first condition very perfect: from the grid division, the abnormal unit's examination to final optimization and grid encryption and so on. Here mainly solves the second and third satisfy conditions.First, we determine some units whose reference directions are consistent using the reference direction method`s fast characteristic, then we take these units as the reference units, carrying on the computation according to the reference unit method, such speed will enhance certainly many. But, considering the rounding error reason around the computer numerical calculus, the reference direction method cannot judge correctly when the included angle between the unit normal and the reference direction is approach. In order to solve this problem, we may relax appropriately the judgment condition, namely reducing included angle size between unit normal and reference direction. If cosα>λ, we think that this unit normal is consistent with the pressing direction, then marking this unit for the seed unit; If cosα<λ, we think that this unit`s normal is inconsistent with the pressing direction, then turning over this unit's normal for 180°to reach consistent with the pressing direction. at one time. To mark this unit for the seed unit. Carrying on the operation like this repeatedly, all normal lines will realize fast to be consistent.It is possibility to appear unreasonable situation when carrying on the equal-space, the main performance is that the grid will present the acute angle or overlapping after the equal-space. This is also the question which the most enterprise meet frequently in actual operations. Its reason is that the radius of curvature is smaller or equal to the equal-space-distance in these regions before dividing the grid. Therefore, this article proposes an equal-space rationality judgment and giving the reasonable value algorithm which solution this question very well. The rationality judgment takes one initialization as a basic point and seeks unreasonable node (These nodes whose minimum distance value with all originating nodes is smaller than equal-space-distance), then it gives fast the reasonable suggestion value using the dichotomy method. These reduce nonessential duplication operations.Highly effective is an algorithm`s core, this article proposes the background grid's thought to support highly effective. In the spatial scope in the model finite element grid, we introduce continual,shape simple space lattice (for example cube, cuboid, circular cylinder, etc), which will wrap the complex space-like surface (its thought is similar to spatial surrounding box)and number each space lattice according to certain rule, then it"load"each unit node to own space lattice, realizing the node space orientation. In the following operation, we no longer aim at the entire grid information, but only aims at the information in the requested scope. It reduce greatly the information quantity which each time analyzes, thus realizes the goal that not only satisfies the precision, but also raises the analysis efficiency greatly.In brief, undergoes the repeated confirmation, the above several algorithms are effective. This will be meaningful development and optimization to pre-processor system in KMAS/One-step.