1990 Fiscal Year Final Research Report Summary
Assessment Method for the Effect of Strain Rate on Fracture Toughness
| Project/Area Number |
63850094
|
|---|
| Research Category |
Grant-in-Aid for Developmental Scientific Research (B).
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
船舶構造・建造
|
|---|
| Research Institution | Kyushu University |
|---|
Principal Investigator |
TOYOSADA Masahiro Faculty of Engineering of Kyushu University , Associate Professor, 工学部, 助教授 (30188817)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
HAGIWARA Ikuto Technical Research Institute of Shin-Nihon Steel Co. LTD , Chief Researcher, 主任研究員
ARIMOCHI Kazushige Technical Research Institute of Sumitomo Metal Works , Chief Researcher, 主任研究員
KAWANO Syunichi Faculty of Engineering of Yamaguchi University , Professor, 工学部, 教授 (40044276)
|
|---|
| Project Period (FY) |
1988 – 1990
|
| Keywords | Strain Rate / Temperature Rise Due To Plastic Work / Strain Rate Temperature Parameter / Constitutive Equation / Dynamic Fracture Toughness / Dynamic CT Test / Dynamic COD Test / Dynamic Thermo-plastic elastic FEM |
|---|
| Research Abstract |
Constitutive relation between strain, stress, strain rate and temperature is conducted by using the strain rate temperature parameter defined by Bennet for the purpose of avoiding the vagued definition of quasistatic condition. For the purpose of obtaining the local temperature rise due to plastic work in the vicinity of a crack tip under dynamical condition, the dynamic thermodplastic-elastic FEM, in which the above constitutive equation and iterative method are used, is developed. It became clear that the plastic work converts around 90 percent of this into the heat and the remaining plastic work converts into another works such as the formation of slip band from the tensile test under several loading rates.
CT tests under several loading rates and 3-point bend tests by using a drop weight testing machine are carried out for the purpose of measuring the strain distribution in the vicinity of a crack tip and the FEM show to give the good agreement with the measuring strain distribution.
Moreover the distributions of the temperature rise near the crack tip of CT specimen due to plastic work under several loading rates are measured by using Thermo Viewer and the FEM results also show the good agreement with the experimental ones. Moreover the FEM results show that the yield stress in the vicinity of a crack tip keeps some constant level as a result of compensating effect of strain rate and temperature on the yield stress. This result supports that the experimental displacement behavior in the dynamic condition is similar to that in the static condition.
From above results, the assessment method for obtaining the fracture toughness under the arbitrary strain rate is proposed by the fracture toughness test under static condition.
|
Research Products
(6 results)
