The Performance of Pressure Vessel Using Concentric Double Cylindrical High Explosive

2004 ◽  
Vol 126 (4) ◽  
pp. 409-413 ◽  
Author(s):  
Toru Hamada ◽  
Yuichi Nakamura ◽  
Shigeru Itoh
Keyword(s):  
High Velocity ◽  
High Explosive ◽  
Maximum Pressure ◽  
Detonation Pressure ◽  
Low Velocity ◽  
High Explosives ◽  
Detonation Process ◽  
Set Up ◽  
Overdriven Detonation ◽  
Detonation Phenomenon

The detonation pressure from the steady detonation of high explosives is a characteristic. Nevertheless, in materials processing using high explosives, there are cases when the detonation pressure does not match the intended pressure. In this investigation, as a new method of generating the overdriven detonation effectively, a double cylindrical high explosive set up using two kinds of explosives was developed, and its basic performance is analyzed. The concentric double cylindrical high explosive set up was composed of a high velocity explosive and a low velocity explosive, and the overdriven detonation was performed in the low velocity explosive. In this experiment, the ion gap was set up in the high velocity explosive and low velocity explosive respectively, and the detonation velocity was measured. The detonation pressure was also measured by setting up a manganin gauge (Kyowa Electric Instrument Co., Ltd.,) at the position where the generation of the overdriven detonation phenomenon was expected. Furthermore, the overdriven detonation process of the concentric double cylindrical high explosive was continually observed by numerical analysis and the framing photography. From the experimental results, the very high pressure region including the mach stem was observed in the low velocity explosive, and the overdriven detonation phenomenon was confirmed. The maximum pressure value of the concentric double cylindrical high explosive set up was 2.3 times higher than the Chapman-Jouguet pressure of the single explosive.

The Performance of Pressure Vessel Using Concentric Double Cylindrical High Explosive

2003 ◽  
Author(s):  
Toru Hamada ◽  
Yuichi Nakamura ◽  
Kenji Murata ◽  
Yukio Kato ◽  
Shigeru Itoh
Keyword(s):  
High Pressure ◽  
Detonation Velocity ◽  
Pressure Vessel ◽  
High Explosive ◽  
Detonation Pressure ◽  
Flyer Plate ◽  
Low Velocity ◽  
High Explosives ◽  
Detonation Velocity And Pressure ◽  
Manganin Gauge

In recent year, it has been hoped to develop a device that generate high pressure in the field of the material consolidation. Therefore a phenomenon of over driven detonation (O.D.D.) [1] that was one of the detonation phenomenons has been researched. The detonation velocity and pressure that is higher than Chapman-Jouguet state generate in the state of O.D.D.. But, in the method of using the flyer plate that has been investigated, it is difficult to apply to the material consolidation since the region where O.D.D. phenomenon generates is very small. Therefore, as a new method of effectively generating O.D.D., the method of combining two kinds of the high explosives was developed. This method is a technique that is generated O.D.D. in the low velocity explosive by making a double cylindrical explosive of the high velocity explosive and low velocity explosive. The detonation pressure of low velocity explosive in a double cylinder was measured by Manganin gauge. The detonation pressure was 2.0 times over higher than the Chapman-Jouguet pressure.

Numerical Study of Overdriven Detonation Phenomenon

2005 ◽  
Author(s):  
K. Mahmadi ◽  
M. Souli ◽  
N. Aquelet
Keyword(s):  
Numerical Study ◽  
Detonation Pressure ◽  
Explicit Finite Element ◽  
Structure Interaction ◽  
High Velocity Impacts ◽  
Detonation Process ◽  
Material Points ◽  
Overdriven Detonation ◽  
Detonation Phenomenon ◽  
Good Agreement

The overdriven detonation refers to detonation process in which the main detonation parameters, such as detonation pressure and propagating velocity, exceed the corresponding Chapman-Jouguet (C-J) values. This kind of detonation can be occurred when the flyer plate of high velocity impacts the explosive. So, in this work numerical simulation of overdriven detonation (following O.D.D.) phenomenon, which brings out higher detonation pressures than C-J pressure of an explosive is considered. The shock-structure interaction in this fast event is modeled by a penalty coupling, which permits to couple a Lagrangian mesh of the plate to material points of a multi-material Eulerian flow. This technique has been used successfully in many areas of applications, including automotive and industrial fields. By using an explicit finite element method, a good agreement between numerical and experimental results will valid penalty coupling capabilities to solve accurately O.D.D. phenomenon.

Analysis of Shell Material Influence on Detonation Process in High Explosive Charge

2016 ◽  
Vol 715 ◽  
pp. 27-32 ◽  
Author(s):  
Igor Balagansky ◽  
Alexey Vinogradov ◽  
Lev Merzhievsky ◽  
Alexander Matrosov ◽  
Ivan Stadnichenko
Keyword(s):  
Explosive Charge ◽  
Symmetry Axis ◽  
High Explosive ◽  
Detonation Front ◽  
Detonation Pressure ◽  
Ceramic Shell ◽  
Shell Material ◽  
Detonation Products ◽  
Transverse Waves ◽  
Detonation Process

The influence of the shell material (copper and silicon carbide) on the detonation process in cylindrical high explosive charge is experimentally and numerically investigated. We observed the significant differences of wave pictures in the detonation products and in the shells, which were due to differences in the sound velocities in the shells and rapid destruction of the ceramic shell under explosion loading. The specific features of a wave picture at the interface HE/ceramics due to desensitization of explosive under loading by an advanced wave in the shell were detected. Those features lead to decreasing of detonation pressure, blurring of the detonation front, and to increasing of mass velocity behind detonation front that is typical for under-compressed detonation. On the symmetry axis of HE charge in the ceramic shell behind the detonation front the long zone with practically constant pressure was observed. We have identified the mechanism of transmission of disturbances from the periphery to the symmetry axis of the HE charge. The source of the emergence of this zone is identified as transverse waves propagating directly behind the detonation front from the periphery to the symmetry axis of the HE charge.

VISUALIZATION OF AN OVERDRIVEN DETONATION PHENOMENON IN A HIGH EXPLOSIVE

1999 ◽  
Vol 6 (4) ◽  
pp. 295-302 ◽  
Author(s):  
Shigeru Itoh ◽  
Zhi-yue Liu ◽  
Shiro Nagano ◽  
Hiroshi Kitaki
Keyword(s):  
High Explosive ◽  
Overdriven Detonation ◽  
Detonation Phenomenon

Investigation of Jet Formation with Overdriven Detonation in High Density Explosive

2007 ◽  
Vol 566 ◽  
pp. 327-332 ◽  
Author(s):  
Hisaatsu Kato ◽  
Kenji Murata ◽  
Shigeru Itoh ◽  
Yukio Kato
Keyword(s):  
Numerical Simulation ◽  
Detonation Velocity ◽  
Tungsten Powder ◽  
High Density ◽  
Shaped Charge ◽  
Detonation Pressure ◽  
Jet Formation ◽  
High Explosives ◽  
Overdriven Detonation ◽  
Penetration Velocity

To increase largely the performance of shaped charge, it is required to generate detonation velocity much higher than CJ velocity or detonation pressure much higher than CJ pressure of existing high explosives. One solution is the application of overdriven detonation phenomena. In this study, the effects of overdriven detonation in tungsten loaded high density explosive on the performance of shaped charge were demonstrated by experiments and numerical simulation. Sample shaped charge was composed of the inner layer tungsten loaded high density PBX and outer layer high velocity PBX. Concentration of tungsten powder in high density PBX was varied from 20 to 60% in mass. The pressure of overdriven detonation in inner layer PBX was measured by PMMA gauge, and was shown to be higher than 50GPa. The experimental results showed that the initial jet velocity and jet penetration velocity in target plates were largely increased by the effects of the overdriven detonation in tungsten loaded high density PBX.

Detection of effort maximality in adults performing isokinetic wrist flexion and extension

2021 ◽  
pp. 1-7
Author(s):  
Mercè Torra ◽  
Eduard Pujol ◽  
Anna Maiques ◽  
Salvador Quintana ◽  
Roser Garreta ◽  
...  
Keyword(s):  
High Velocity ◽  
Healthy Male ◽  
Wrist Flexion ◽  
Low Velocity ◽  
Wrist Extensor ◽  
Submaximal Effort ◽  
The Difference ◽  
Muscle Groups ◽  
Maximal Effort ◽  
Flexion And Extension

BACKGROUND: The difference between isokinetic eccentric to concentric strength ratios at high and low velocities (DEC) is a powerful tool for identifying submaximal effort in other muscle groups but its efficiency in terms of the wrist extensors (WE) and flexors (WF) isokinetic effort has hitherto not been studied. OBJECTIVE: The objective of the present study is to examine the usefulness of the DEC for identifying suboptimal wrist extensor and flexor isokinetic efforts. METHODS: Twenty healthy male volunteers aged 20–40 years (28.5 ± 3.2) were recruited. Participants were instructed to exert maximal and feigned efforts, using a range of motion of 20∘ in concentric (C) and eccentric (E) WE and WF modes at two velocities: 10 and 40∘/s. E/C ratios (E/CR) where then calculated and finally DEC by subtracting low velocity E/CR from high velocity ones. RESULTS: Feigned maximal effort DEC values were significantly higher than their maximal effort counterparts, both for WF and WE. For both actions, a DEC cutoff level to detect submaximal effort could be defined. The sensitivity of the DEC was 71.43% and 62.5% for WE ad WF respectively. The specificity was 100% in both cases. CONCLUSION: The DEC may be a valuable parameter for detecting feigned maximal WF and WE isokinetic effort in healthy adults.

scholarly journals Studying the Depth Structure of the Kyrgyz Tien Shan by Using the Seismic Tomography and Magnetotelluric Sounding Methods

Geosciences ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 122
Author(s):  
Irina Medved ◽  
Elena Bataleva ◽  
Michael Buslov
Keyword(s):  
Seismic Tomography ◽  
High Velocity ◽  
Fault Zones ◽  
Magnetotelluric Sounding ◽  
Tien Shan ◽  
High Resistivity ◽  
Low Velocity ◽  
Low Resistivity ◽  
Velocity Models ◽  
Fluid Saturation

This paper presents new results of detailed seismic tomography (ST) on the deep structure beneath the Middle Tien Shan to a depth of 60 km. For a better understanding of the detected heterogeneities, the obtained velocity models were compared with the results of magnetotelluric sounding (MTS) along the Kekemeren and Naryn profiles, running parallel to the 74 and 76 meridians, respectively. We found that in the study region the velocity characteristics and geoelectric properties correlate with each other. The high-velocity high-resistivity anomalies correspond to the parts of the Tarim and Kazakhstan-Junggar plates submerged under the Tien Shan. We revealed that the structure of the Middle Tien Shan crust is conditioned by the presence of the Central Tien Shan microcontinent. It manifests itself as two anomalies lying one below the other: the lower low-velocity low-resistivity anomaly, and the upper high-velocity high-resistivity anomaly. The fault zones, limiting the Central Tien Shan microcontinent, appear as low-velocity low-resistivity anomalies. The obtained features indicate the fluid saturation of the fault zones. According to the revealed features of the Central Tien Shan geological structure, it is assumed that the lower-crustal low-velocity layer can play a significant role in the delamination of the mantle part of the submerged plates.

Effective use of overdriven detonation in high explosives

2003 ◽  
Author(s):  
Masahiko Otsuka ◽  
Hideyuki Morimoto ◽  
Shirou Nagano ◽  
Eiji Hida ◽  
Kenji Kuroki ◽  
...  
Keyword(s):  
High Explosives ◽  
Overdriven Detonation ◽  
Effective Use
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