• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.12
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• pp.1004-1011
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• 2018

Recently, pyrotechnic separation nut has attracted a considerable attention because of its shock reduction effect among various pyrotechnic mechanical devices. However, its bolt loosening behavior under transverse vibration has not been studied sufficiently, since segmented nuts are utilized instead of conventional nut in pyrotechnic separation nut. With the background, bolt loosening analyses are carried out referring to Junker vibration test. The analysis procedure consists of two steps. The first step is the bolt fastening step, screwing the bolt by fastening torque. The second step is the bolt loosening step under transverse vibration. Through the procedure, bolt loosening behaviors are obtained, and the effect of clearance on loosening behavior is closely investigated for reliable design of pyrotechnic separation nut.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.27 no.2
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• pp.213-220
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• 2017

Pyroshock produced by the pyrotechnic devices can induce failures in nearby electronic devices. To handle and mitigate pyroshock inducing problems, appropriate measurement of pyroshock is essential. In this study, pyroshock measurement technique is established using laser Dopper vibrometers (LDVs) and shock accelerometers. Pyroshock produced by the explosive bolts and the pyrotechnic initiators under various environments is measured. The characteristics of pyroshock including the effects of supporting structures, propagation form on thin plate, sensor (contact and non-contact) types are discussed.

• Journal of the Korea Institute of Military Science and Technology
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• v.21 no.4
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• pp.413-421
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• 2018

The pyroshocks can cause failure of electronics devices and structures. Metal-metal impact methods are utilized to simulate mechanical pyroshock, and to adjust the knee frquency of the SRS(Shock Response Spectrum) through resonant structures. In this paper, the major parameters of pyroshock simulation device which affect the SRS were examined. Through the Hertzian contact law and the modal characteristics of the resonant bar, it was found that the SRS is affected by the length and mass of a bar and various impact conditions such as velocity and mass of impactor. The characteristics due to the geometric parameters of a resonant bar was analyzed by performing FEA and also the resonant bar was designed and fabricated. Through the pyroshock simulation test, the characteristics of SRS due to the variation of impact parameters were examined.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.363-366
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• 2006

In general, pyrotechnic shock or pyroshock is generated during the operation of separation devices, which use explosives, such as pyrobolt, puronut, purocutter, linear shape charge, and so on. During the flight of launch vehicle, pyroshock is mainly produced at the events of satellite separation, fairing separation and stage separation. In this paper, characteristics of pyroshock are introduced in the first place and measured shock result data at the UMR of satellite mock-up during the separation tests of satellite and fairing are suggested. These results are compared with the suggested pyroshock test specification of satellite, and it finally confirms that the specification is reasonable for the qualification of satellite against pyroshock.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.2
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• pp.75-85
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• 2016

A pyrotechnic system consisting of donor/acceptor pair separated by a gap relies on shock attenuation characteristics of the gap material and shock sensitivity of the donor and acceptor charges. Despite of its common use, numerical study of such pyrotechnic train configuration is seldom reported because proper modeling of the full process requires precise capturing of the shock wave attenuation in the gap prior to triggering a full detonation of high explosive and accurate description of the high strain rate dynamics of the explosively loaded inert confinements. We apply a Eulerian level-set based multimaterial hydrocode with reactive flow models for pentolite donor and heavily aluminized RDX as acceptor charge. The complex shock interaction, critical gap thickness, acoustic impedance, and go/no-go characteristics of the gap test are quantitatively investigated.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.340-343
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• 2011

Explosive bolts are reliable and efficient mechanical fastening devices having the special feature of a built-in release. The disadvantage of explosive bolt lies in that it is based on the high explosive effect of a pyrotechnic charge. The aim of the present work is to propose a pyrotechnically releasable mechanical linking device for two mechanical elements that does not suffer from such drawbacks. The pyro-lock using the pressure cartridge has the release characteristic without fragmentation and minimum pyro-shock. The present work is focused on the design, the interpretation of structure, the separation mechanism, separation force, and the results of various tests.

• Journal of the Korean Society of Propulsion Engineers
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• v.9 no.1
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• pp.27-34
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• 2005

The present work has been developed the study of interpretation of separation behavior in gas expansion separation(GES) bolt which has the separation characteristics without fragmentation and minimum pyre-shock during the operation of the explosive bolt. In order to obtain the performance of minimum pyre-shock, the present work used non-compressive material instead of separation explosives. The use of the interpretation processor could be extensively helped to design the shape and the amount of explosives in the explosive bolt having complex geometry, and to analyse the separation behavior during the operation. It is also proved that the GES bolt is the most suitable the separation system necessary to minimum pyre-shock and non fragmentation compare with others.

• Journal of KSNVE
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• v.27 no.1
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• pp.7-11
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• 2017

• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.5
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• pp.46-51
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• 2015

Multi-channel DAQ system was developed to predict propagation characteristic of the shock wave generated by linear explosive. The system can generate shock wave from 1000 points per second using a pulsed laser and simultaneously obtain the shock wave signals using 15 chanel contact sensor. The system is expected to pridict the propagation characteristics of various linear explosive-induced pyroshock because it can be used with a user-defined time delay that corresponds to detonation speed of the linear explosive.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.208-211
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• 2007

Separation Devices have two functions. These two functions are to bond and to separate two bodies. This paper is about separation devices which use explosives to separate their bodies. Explosive bolt is separated with two bodies when the explosives in the body detonated. The good things of explosive bolt are that it has simple operational system and it is made of few parts. But it has side effects; fragment and pyre-shock. To avoid these side effects gas expansion separation(GES) bolt and pressure cartridge actuation separation(PAS) devices are invented. These use pressure to separate their bodies. The pressure is generated when explosives are burned. But the sizes of PAS devices are bigger than explosive bolts. And GES bolt has a mechanically lower bonding ability than that of explosive bolt. When you design separation devices, it is recommended to know operational system and characteristics of separation devices, to design best one.