1999 Fiscal Year Final Research Report Summary
Fundamental Research on Computer Simulation of Damage and Fracture Process
| Project/Area Number |
10650082
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Materials/Mechanics of materials
|
|---|
| Research Institution | Nagoya University |
|---|
Principal Investigator |
SUMIO Murakami Nagoya University, Department of Mechanical Engineering, Professor, 工学研究科, 教授 (10023053)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
KAWAI Masamichi Tsukuba University, Department of Structural Engineering, Associate Professor, 構造工学系・助教授 (90169673)
KANAGAWA Yasushi Kochi University, School of Agriculture, Professor, 農学部, 教授 (90023481)
MIZUNO Mamoru Nagoya University, Department of Mechanical Engineering, Assistant Professor, 工学研究科, 講師 (70239250)
|
|---|
| Project Period (FY) |
1998 – 1999
|
| Keywords | Damage / Fracture / Crack / Simulation / Damage Mechanics / Finite Element Method / Mesh Dependence / Stress Singularity |
|---|
| Research Abstract |
The present project aims at the development of systematic computational method of damage and fracture analysis on the basis of Continuum Damage Mechanics (CDM) and Finite Element Method (FEM), and to discuss the related fundamental problems. The results of the project are summarized as follows :
1. In order to discuss the mathematical and numerical modeling of creep crack growth, the distribution of grain boundary cavities around a mode I creep crack in Oxgen Free High Conductivity (OFHC) copper are observed by an optical microscope. The contour of damage field can be represented by a semi-circle in front of the crack and by straight lines parallel to the crack surface.
2. As a model to simulate the probabilistic character of creep crack process, a FEM analysis was performed by assuming Gaussian distribution for the critical (threshold) value of Damage Variable of each FEM element. Then a similar analysis was also performed by assuming that the orientation of damaging grain boundaries distributes randomly and by specifying the corresponding microstructural mechanical properties to each element. These analysis were found to simulate well the creep fracture process.
3. Stress singularity a crack tip is one of the cause of mesh-dependence of numerical results of damage-fracture simulation. Thus the effects of the damage field on the stress singularity at crack tips of mode I and mode III cracks were analysed by a semi-inverse method by postulating a semi-circle damage field. It was found that the HRR singular field may become nonsingular due to the existence of a damage field.
4. When a creep crack develops fast, the effects of stress change at the crack-tip may be significant Similar creep crack analysis were performed also for mode I and mode III cracks in elastic-creep-damage material. The difference of resulting crack-up stress field from those of HRR field of non-linear material and HR field for elastic-creep material was elucidated.
|
