1997 Fiscal Year Final Research Report Summary
A Study on Development of Explosion at the Central Axis of Cylinders and lts Applications
| Project/Area Number |
08651112
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
資源開発工学
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| Research Institution | Kumamoto University |
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Principal Investigator |
HIROE Tetsuyuki Kumamoto Univ., Faculty of Eng., Professor, 工学部, 教授 (90218826)
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| Co-Investigator(Kenkyū-buntansha) |
FUJIWARA Kazuhito Kumamoto Univ., Faculty of Eng., Lecturer, 工学部, 講師 (50219060)
MATSUO Hideo Kumamoto Univ., Faculty of Eng., Professor, 工学部, 教授 (00040395)
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| Project Period (FY) |
1996 – 1997
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| Keywords | Wire Explosion / Cylindrical Exploding Detonation Wave / Uniform Expansion at High Velocity / Constitutive Equation / High Speed Loading |
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| Research Abstract |
An exploive loading technique is applied to study the uniform expansion of steel cylinders at high strain rates. As a preliminary study, several columns of powder PETN high exploive are initiated at the center line by exploding a copper wire, using a impulsive discharge current from a capacitor bank. It is found that generated cylindrical diverging detonation waves are uniform circumferentially and axially within the time jitters of (]SY.+-。[) 0.3-0.4ms, when the length of the column is less than 190-240 mm and the diameter is more than 6-8 mm. The streak camera record of a cone of the PETN indicates that stable detonation is achieved at the radius of 3-4 mm.
The generation of cylindrical diverging detonation is adopted to expand cylinders of carbon steel and stainless ateel (length : 100-60 mm, Inner dia. : 28 mm, thickness : 3 mm). The PETN columns with the same length and three kinds of diameters (12 mm, 16 mm, 28 mm) sre installed inside the steel cylinders. Expanding shadows and surface velocities of the cylinders are recorded, using an IMACON and a laser interferometry system (VISAR) respectively. The framing photos show a axially almost uniform expansion and the streak records give the time-histories of symmetrically expanding diameter at the midlength of the cylinders. It is known that the cylinders expand with rather constant velocity after the initial acceleration stage and the average circumferential strain rates reach up to around 1 to 4 x 10^4 ^<-1> for three cases. The framing camera records of the shadow indicate that the axial displacement during expansion is negligibly small. One- and two-dimensional (AUTODYN 2D) numerical simulations are performed with various stress-strain curves and a reasonable constitutive relation is derived from the comparison with experimental results. It is demonstrated that the proposed loading technique is available to obtain fundamental data on expansion process of cylinders at very high strain rates.
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