A Numerical Analysis of Material Nonlinear Problems by Damage Evolution Model
| Jazyk: | japonština |
|---|---|
| Rok vydání: | 1995 |
| Předmět: | |
| Zdroj: | 法政大学計算センター研究報告 = Bulletin of Computer Center, Hosei University. 8:1-8 |
| ISSN: | 0913-8420 |
| Popis: | 本論文は有限ひずみ弾塑性損傷材料モデルに対して非線形数値解析問題の関点から研究したものである．まず最初に，損傷材料に対して連続体力学の考えから構成方程式を誘導し，損傷進展法則に対する考えをまとめる．次に，従来の有限要素法の非線形問題に対して，リターンマッピングアルゴリズムを導入する事により，解の安定性と精度の向上をはかる．また，局所損傷問題に対するポストプロセッサの開発を行う．ここではくり返し疲労と延性損傷に対する損傷進展問題のいくつかの解析を行い考察を加える．最後に実際の有限要素法により材料非線形問題の数値解析例をいくつか示し従来のモデルとの比較，検討を行うものである． This work addresses the computational aspects of a model for elastoplastic damage at finite strains. The model is a modification of previously established model for large strain elastoplasticity described by Peric et al. which is here extended to include isotropic damage and kinematic hardening. Within the computational scheme, the constitutive equations are numerically integrated by an algorithm based on operator split methodology (elastic predictor-plastic corrector). The Newton-Raphson method is used to solve the discretized evolution equation in the plastic corrector stage. A numerical assessment of accuracy and stability of the integration algorithm is carried out based on iso-error maps. To improve the stability of the local N-R scheme, the standard elastic predictor is replaced by improved initial estimates ensuring convergence for large increments. Several possibilities are explored and their effect on the stability of the N-R scheme is investigated. A post processor is fully described which allows the calculation of the crack initiation conditions from the history of strain components taken as the output of a finite element calculation. The localization of damage allows the coupling to be considered only for the damaging point for which the input strain history is taken from a classical structure calculation in elasticity or elastoplasticity. Some examples show its ability to model suctilefailure in one or multi dimensions, brittle failure, low and high cycle fatigue with the non-linear accumulation, and multi-axial fatigue. The finite element method is used in the approximation of the incremental equilibrium problem and the resulting equations are solved by the standard Newton-Raphson procedure. Two numerical examples are presented. The results are compared with those obtained by the original elastoplastic model. |
| Databáze: | OpenAIRE |
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