Research On Some New Techniques For Forming Simulation Software Platform Of Automobile Panel

0. PrefaceThe development of autonomous CAE software technology and industry has great significance on improving the capability of the core competitiveness and independent innovation ability of Chinese equipment manufacturing industry, breaking through embargoes barriers and monopoly from developed countries, ensuring national security, and implementing national long-term technology development planning, cohesion and creating innovative talents. To enhance the development of auto body stamping simulation CAE software with state-owned and independent intellectual property rights, on one hand, we need to continue to resove the technical problems of sheet metal forming and develop the corresponding core algorithm with independent intellectual property rights; on the other hand, we need to create and develop standards for the CAE basic software development platform and maximize the integration of the domestic CAE software development resources.In this paper, we launched a forming simulation software development platform research under the National Automotive Electronics major projects of high-tech industry "CAD/CAE/CAM software platform for digital auto body parts fine design and manufacturing"(SDRC high-tech 2042), the National Outstanding Youth Science Fund "The CAD expert system theory based KBE of stamping design and the research on the polymer forming theory and calculation method "(10125208) and the Ministry of Science and Innovation Fund "Stamping forming simulation technology applications". At the same time, based on the platform, we focus on the design and implementation for the "automobile panel stamping pre-processing system". Some of the key modules and key algorithm are also conducted in-depth study.1. Forming simulation software development platform of auto body part (KMAS / COMX)Cross-platform features, xml bus technology, service-oriented (SOA) architecture, component-oriented visual development interface and so on are the main directions of CAE software development platform.This paper built a simplified version of COM kernel, based on the principles and norms of Microsoft's COM technology, for the implementation of a variety of operating systems (Windows / LINUX / UNIX, etc.). On this basis, we developed a forming simulation basic software development platform with "micro-kernel + plug-in" mechanism, named "A simplified Component Object Model for X platforms" (referred to as COMX development platform, where X on behalf of Windows / LINUX / UNIX operating system). Based on COMX platform, we developed some basic application modules (Such as: core CAD database component based ACIS, basis graphics visualization component and graphics pickup component based OpenGL) and some basic development tools (Such as: visual interface development tool-KUL and component wizard tool for COMX).2. Die face design module (KMAS / Die Face)Automobile panels have large geometric dimensions, complex shapes and high quality required surfaces, therefore, a strong support for CAD capabilities is needed for die face design system.This paper designs and develops a die face design module (KMAS / Die Face) on the COMX development platform, which applies ACIS as the core of the underlying CAD database, integrates the forward and reverse die face design concept. We can get a complete parametric mold-type surface of covering parts through three main steps, the parts preparation (including: hidden flange, fillet, fill holes, smoothing outer boundary, symmetry / dual-mode segmentation, and parametric split parts), generating binder surface and generating addendum surface.3. Mesh generation module (KMAS / Mesh Generation)The quality of mesh has a direct impact on the calculation accuracy and efficiency of finite element analysis. Automatic mesh generation has become one of the great key technologies of finite element analysis.In this paper, based on the study of the advantages and disadvantages of current finite element mesh generation methods, we presented an improved grid mesh generation algorithm, which combines the advantages of regular grid method and the Delaunay triangulation algorithm and generated hybrid elements of quadrilateral element and a small number of triangle mesh, this ensured the best overall performance with the good localized states. Based on the grid method, the mesh generation module (KMAS / Mesh Generation) was designed and developed on the COMX development platform for pre-processing system.In the mesh generation module implementation process, innovative research results included in this paper are: the improved grid mesh generation algorithm; the border restore iterative algorithm based on the closest point connection.4. Pre-processing system for increment method (KMAS / Increment)Pre-processing system can complete the initialization of the calculation model work and provide the necessary raw data for calculation through buliding finite element model, material model, boundary conditions, settings, etc…In this paper, optimization of pressing direction, normal consistency and tool assembly are studied in detail and the improved projects are proposed respectively. Ultimately the pre-processing system for incremental method (KMAS / Increment) is constructed using the common mouse-drived graphical user interface as the basic framework. The system can greatly reduce the operating time and improve work efficiency through standardized workflow and user-friendly interface for navigation.In the pre-processing system implementation process, this paper carried out innovative research achievements as listed below: A stamping direction optimization algorithm based on finite element model; a fast normal consistency algorithm which has nothing to do with the stamping direction and suited to multiply connected domains; an automatic pre-assembly algorithm for tools with improved "global cycle + local search".