STUDY ON MICRO MECHANISM OF DUCTILE FRACTURE

韧性断裂微观机制研究

• 批准号: 03402026
• 负责人: SHIOYA Tadasi
• 金额: $ 20.54万
• 依托单位: UNIVERSITY OF TOKYO
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (A)
• 财政年份: 1991
• 资助国家: 日本
• 起止时间: 1991 至 1994
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-03402026/
• 关键词: Ductile Fracture; Void; Tensile Test; Ultrasonic Method; Stress Triaxiality; Constitutive Equation; Effect of Size; Dimple

Microscopic procedure of ductile fracture of material consists of three processes ; 1) Voids nucleation at the second phase particles and/or the triple points of grain boundaries, 2) The voids growth under multi-axial stress states, and 3) The voids coalescences to lead final fracture.In the project, experimental studies are prosecuted on the ductile fracture of mild steel and aluminum specimens under multi-axial stress states. The ultrasonic wave transmission tests are performed measuring the attenuation of the wave during the fracture process in real time to evaluate the voids growth process. The fracture surfaces are observed by scanning electron microscope and optical microscope. The dimples appeared on the fracture surfaces are statistically processed to correlate the stress states and material composition.In the analysis, numerical calculations are carried out to simulate the voids nucleation and growth processes with proposed criteria of nucleation condition and growth rule. The growth process of an isolated void is also analyzed with time-dependent constitutive relation of material. The elongation of the void shape in relation with the initial shape and the applied stress state is examined.The experimental results and the analysis are compared to explain the microscopic process of the ductile fracture qualitatively and quantitatively.

材料韧性断裂的微观过程由三个过程组成； 1) 第二相颗粒和/或晶界三相点处的空洞成核，2) 多轴应力状态下的空洞生长，3) 空洞合并导致最终断裂。在该项目中，进行了实验研究多轴应力状态下低碳钢和铝试样的延性断裂。进行超声波传输测试，实时测量断裂过程中波的衰减，以评估孔隙增长过程。通过扫描电子显微镜和光学显微镜观察断口形貌。对断裂表面出现的韧窝进行统计处理，以将应力状态和材料成分关联起来。在分析中，通过提出的成核条件和生长规则标准，进行数值计算来模拟空洞的成核和生长过程。还利用材料随时间变化的本构关系分析了孤立空隙的生长过程。检查了孔隙形状的伸长与初始形状和施加应力状态的关系。将实验结果与分析结果进行比较，定性和定量地解释了韧性断裂的微观过程。

项目成果

Tetsuya Morimoto: "MEASUREMENT AND ANALYSIS OF MICRO VOIDS NUCLEATION AND GROWS IN DUCTIL FRACTURE OF FCC METAL (APPLICATION OF ULTRASONIC FLOW DETECTION METHOD ON DYNAMIC FRACTURE TEST)" Proceedings of the 1993 Annual Meeting of JSME/MMD. No.73-930. 901-

Tetsuya Morimoto：“FCC金属延展性断裂中微孔洞成核和生长的测量和分析（超声流动检测方法在动态断裂试验中的应用）”JSME/MMD 1993年年会论文集。

Tadashi Shioya: "A MODEL OF ELLIPTICAL VOID GROWTH IN DUCTILE FRACTURE" Pre-print of JSME. No.910-62, Vol.A. 280-282 (1991)

Tadashi Shioya：“延性断裂中的椭圆形空洞生长模型”JSME 预印本。

Tadashi Shioya: "MODEL OF ELLIPTIC VOID GROWTH IN DUCTILE FRACTURE" Transactions of JSME. No.58 (556) A. 75-80 (1992)

Tadashi Shioya：“延性断裂中的椭圆形空洞生长模型”JSME 交易。

Tadashi Shioya: "MICROMECHANISM OF VOID NUCLEATION AND GROWTH IN DUCTILE FRACTURE,Proceedings of the 34th Japan Congress on Materials Research" 257-261 (1991)

Tadashi Shioya：“延性断裂中空洞成核和生长的微观机制，第 34 届日本材料研究大会论文集”257-261 (1991)

塩谷 義: "延性破壊における楕円空孔成長モデル" 日本機械学会第69期全国大会講演会講演論文集A. 280-282 (1991)

Yoshi Shioya：“延性断裂中的椭圆孔生长模型”第69届日本机械工程学会全国会议论文集A.280-282（1991）