Study Of Some Related Key Algorithm In Pre-and Post-processing Subsystem Of FASTAMP

Sheet metal stamping process is widely used in automobile, aircraft, shipbuilding,household appliance and other industries with high production efficiency, good productperformance and work material saving. Especially, in the automobile manufactureindustry, most pieces of an automobile are made with stamping process. The cover pieceproduct is the key link in the automobile product development, which is endowed with thevivid characters of short market life cycle, large physical dimension, form changingfrequently, high forming quality requirements. At the product design stage, it is hard to evaluate forming process and quality of theproduct effectively. Traditionally, both cover piece product finished and die designedmostly depend on experience and die setting. So, it is urgent necessary to have a kind ofoperative analysis method to instruct product design. The finite element inverse approachcan simulate numerically product forming well and become gradually a useful analysismethod at the cover piece development stage of a new automobile. It is very useful thatthe approach can analyze and evaluate the product subsequent process usability, shortenproduct development cycle, reduce the manufacturing cost at the stage. Related algorithm problems are studied in the pre and post process subsystem of thefinite element simulation system, FASTAMP, which is based on inverse approach anddeveloped by State Key Laboratory of Plastic Forming Simulation and Die & MouldTechnology, HUST. And the post process system of FASTAMP is developed. In the pre process system, the quality of element meshed is checked. A new searchingalgorithm is proposed which can build the element topological connection relationshipquickly. Based on the relationship, the element deficiencies such as duplicate element, andan element edge shared by many elements are checked and recovered. According to therequirement of the calculation, the functions that can reverse the element normal directionautomatically and check element negative angle dynamically, are completed. In the post system, the physical quantity distribution displaying algorithms of finiteelement analysis are studied, and three algorithms of element mode, contour mode andsection mode are achieved. A new contour algorithm based on dynamically partitioningphysical quantity distribution zone, is proposed, which can execute quickly and efficiently.According to the requirement of the post system, a displaying algorithm about physicalquantity distribution in a section is proposed. And then the merits and demerits of thethree modes are compared. IIThe foundation of Forming Limit Diagram(FLD) is studied from two aspect oftheory and experiment. The Wrinkle Limit Diagram is introduced to extend theconventional FLD. Then the new FLD can reflect not only the tendency of the reducing inthickness and the fracture but also the tendency of the wrinkling up relatively right. At themeantime, the insufficient forming area is introduced to reflect the phenomenon of theinsufficient rigidity of stamped product, bulging, micro ripple, which are caused by theinsufficient forming. So the final FLD can analyze the forming of an automobile coverpiece easily. Through the many system test and practical industrial application, the stability andpracticability of the post process subsystem is demonstrated. And the functions of thesystem meet the need of the finite element analysis.