Development Of Implicit Nonlinear Finite Element Analysis Framework Based On SiPESC

With the development of modern engineering technology and the wide application of new types material and structure, traditional linear finite element analysis cannot fit the need for engineering computation. Nowadays, advanced computer hardware has made nonlinear finite element method in large-scale engineering analysis a reality. Nonlinear finite element analysis has become an essential tool in many engineering fields such as mechanical, civil, aerospace engineering and so on.Nonlinear finite element software can be divided into two categories:special and common. Special software is designed for specific engineering fields and problem while common software is designed for various engineering fields with abundant analysis abilities. Nowadays, foreign common softwares such as ABAQUS and ANSYS have been well developed but our domestic common software is falling behind significantly. We can only use foreign common software or make some quite limited secondary development and this situation is adverse to boost core competence of domestic engineering and manufacturing.In this thesis, a common implicit nonlinear finite element analysis framework is designed and developed based on open finite element platform SiPESC.FEMS. The framework is based on plug-in plus micro core design mode and large-scale engineering database SiPESC.ENGDBS. Several element formulations, material constitutives and incremental-iterative algorithms have been introduced and its dynamic adding and combination have been implemented via factory mode and polymorphic mechanism. These algorithms are now widely used in large commercial software and tested by numerous actual engineering benchmark examples. Base on the framework in this thesis, these detailed analysis abilities have been implemented:(1) Element Formulation:several three dimensional continuum elements (including mean dilatation, F-Bar techniques), ability to handle large displacement/strain and nearly-incompressible problem.(2) Material Constitutive:large strain hyper-elastic constitutive (nearly-incompressible Neo-Hookean model), elasto-plastic constitutive (isotropic hardening Mises model) and elasto-viscoplastic constitutive (Pierce/Perzyna model).(3) Incremental-Iterative Algorithm:arc-length method for equilibrium path following, several techniques to improve convergence performance (automatic timestep control, dof solution prediction, line search).Several numerical examples (nonlinear post-buckling problem, large strain material uniaxial test et al.) have been given compared with large-scale commercial nonlinear FEA softwares ANSYS and ABAQUS. The results demonstrate the correctness and analysis abilities of the implicit nonlinear finite element framework developed in this thesis.