| Project/Area Number |
14205019
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Materials/Mechanics of materials
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| Research Institution | Kobe University (2004)
神戸商船大学 (2002-2003) |
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Principal Investigator |
NISHIOKA Toshihisa Kobe University, Faculty of Maritime Sciences, Professor, 海事科学部, 教授 (60018067)
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| Co-Investigator(Kenkyū-buntansha) |
FUJIMOTO Takehiro Kobe University, Faculty of Maritime Sciences, Associate Professor, 海事科学部, 助教授 (60314514)
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| Project Period (FY) |
2002 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥55,510,000 (Direct Cost: ¥42,700,000、Indirect Cost: ¥12,810,000)
Fiscal Year 2004: ¥6,890,000 (Direct Cost: ¥5,300,000、Indirect Cost: ¥1,590,000)
Fiscal Year 2003: ¥12,090,000 (Direct Cost: ¥9,300,000、Indirect Cost: ¥2,790,000)
Fiscal Year 2002: ¥36,530,000 (Direct Cost: ¥28,100,000、Indirect Cost: ¥8,430,000)
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| Keywords | Moving Finite Element Method based on Delaunay Automatic Triangulation (MFEMBOAT) / crack tip total energy flow flux critical criterion / Coherent Gradient Sensing (CGS) Method / Ultrahigh-speed Video camera / Transonic Interface Fracture / Mach Shock wave / High Energy Fracture Testing Machine / マッハ衝撃波線 / coherent gradient sensingCGS法 / 高速き裂進展 / 超高速度撮影 / き裂面粗さ / 動的J積分 / C.G.S.法 / 移動有限要素法 / 遷音速破壊 / 界面き裂問題 / 接触 / 摩擦 |
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| Research Abstract |
In experimental aspect, using the presently developed spring constraint loading machine, dynamic fracture tests in homogeneous materials were carried out. As the results, a limiting fast fracture that exceeds 75% of the shear wave velocity c_s of the material was successfully recorded by the presently developed world most advanced ultrahigh-speed video camera system (maximum framing rate : one million frames per second, 10 ns pulse exposure time) this fracture velocity exceeds the limiting crack velocity predicted by the near-tip singular stress field theory. However, taking account of the higher order terms of the near-tip stress field It was theoretically proved that the ultrahigh-sped straight fracture of.75^c_s is possible.to occur Furthermore, relation ship between crack-tip total energy flow flux (ψ_<totai> total energy flux in to the propagating crack tip per unit time) and fracture surface roughness was clarified. It was found that the fracture surface roughness increases for increasing ψ_<total>. Fracture surface roughness may triggers dynamic crack branching fracture.
The governing condition of dynamic crack branching has been a long-term unsolved problem for humankind. In our previous experimental studies, we have proved the critical crack-tip total energy flow flux criterion (dynamic two crack branching occurs when the crack-tip total energy flow flux ψ_<total> total exceeds a critical material value)
In our laboratory, very versatile moving finite element method based on Delaunay automatic triangulation (MFEMBOAT) has been developed. Using MFEMBOAT, dynamic multiple crack branching phenomena was firstly succeeded. The simulation results proved the critical crack-tip total energy flow flux criterion is also valid for the dynamic multiple crack branching.
Keywords : (1) 2),(3)Coherent Gradient Sensing(CGS)Method, (4)Ultrahigh-speed Video camera, (5)Transonic I Interface Fracture, (6)Mach Shock wave, (7)1High Energy Impact Fracture Testing Machine
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