Pyrotechnic Devices Research Articles

The effect of several factors on energy characteristicsand burning of pyrotechnic compositions based on silic and trilead tetraoxide in some pyrotechnic devices

Pyrotechnic ignition is one of the important parts of the delay timing devices found in fuses and rockets to provide operational reliability according to technical requirements. In this study, the burning rate and some energy characteristics of the pyrotechnic ignition were described. The research results showed that pyrotechnic compositions containing 85.0% Pb3O4, 15.0% Si, and 1.0% NC (over 100%) had a high and stable burning rate (109.0 mm/s) and good ignition ability.

Study on pyroshock response of micro-satellite pyrotechnic cutter

When the micro-satellite panel is deployed in orbit, it needs to be unlocked by the pyrotechnic device. The high-amplitude pyroshock environment generated in the unlocking process is fatal to the sensitive components on the satellite. Therefore, accurate and quantitative analysis of the structural response caused by the explosion can better understood the transmission characteristics of pyroshock, so that effective isolation methods can be carried out. In this paper, the finite element model of the pyrotechnic cutter is established in LS-Dyna, and the explosive unlocking process of the pyrotechnic cutter is simulated by the Particle Blast Method (PBM). The whole motion process of the cutter from unlocking to cutting off the pretightening rod is obtained, the distribution of stress and the propagation law of pyroshock wave are extracted. The results show that before unlocking, the explosion shock is the main part of the pyroshock, while after unlocking, it is mainly caused by the prestress release of the pretightening rod and the impact of the cutter hitting the cutting board. Explosive shock is the main factor affecting the near-field pyroshock, while the far-field pyroshock is mainly affected by the impact. To verify the accuracy of the simulation, a unlock test of pyrotechnic cutter are performed, the acceleration response values of the main reference points are obtained, and the results show that the two results are in good agreement in time domain and frequency domain. Based on the study of the separation characteristics, some suggestions on the optimization of damping buffer are proposed here.

Self-driven intelligent curved hinge based on shape-morphing composites

The space deployable structures based on shape memory polymer composites (SMPCs) possessed excellent self-deployable performance, which effectively avoided the impact and electromagnetic pulse (EMP) caused by the explosion of pyrotechnic devices. In this work, two types of self-driven curved hinges with different angles of 80° and 115° (Type 80 and Type 115) were designed based on SMPCs. The thermomechanical properties and time–temperature-dependent viscoelastic behaviors of SMPCs were systematically investigated. The three-point bending performance and cyclic shape memory performance of the developed hinges were also characterized. In addition, the deployment performances of Type 80 driven 350 g object under different heating powers were investigated in the environment of ± 70 °C and 103 Pa atmospheric pressure. A staircase-like heating strategy was proposed to achieve precise and controllable deployment under this environment. The developed self-driven curved hinges were expected to have tremendous application potential on the flap actuators and optical payload rotating platforms of the satellites.

Ban on New year's Fireworks Reduces Severe Hand Injuries: A Nationwide Multicentre Study On The Prohibition Of Pyrotechnics Due To Covid-19 Restrictions

Injuries caused by explosions or pyrotechnic devices can lead to severe hand injuries with potential long-term consequences for both the affected individual and the healthcare system. The implementation of a nationwide ban on fireworks during the New Year festivities was only temporarily enforced as part of the protective measures during the Covid-19 pandemic. These two exceptional years provide an opportunity for evaluation as a model experiment to demonstrate the impact of a fireworks ban on the frequency of explosion-related hand injuries. In a multicentre study, five German hand trauma centres retrospectively collected and analysed all pyrotechnic-related injuries that occurred within seven days around the New Year celebration between 2017 and 2023. Severe hand injuries from explosions were significantly less frequent at New Year celebrations during the pandemic period compared with data collected in the years before and after Covid-19. After the return to regular sales laws and celebrations in December 2022, a significant increase in injuries was observed, surpassing even the pre-Covid period. Epidemiological data confirmed a high proportion of minors and male victims. The highest number of injuries was observed on New Year's Eve and the first day of January, with adults mainly being injured during the festivities, while children and adolescents were mainly injured during the first days of January. A national ban proved to be an effective method to prevent severe hand injuries caused by explosive devices and their lifelong consequences. The data obtained in this multicentre study can serve as a basis for informed policy action.

Ocena ryzyka przypadkowej inicjacji półfabrykatów zawierających artykuły pirotechniczne o przeznaczeniu technicznym w branży motoryzacyjnej

The identification of the danger of accidental initiation, respectively the establishment of the causes and the possibilities that can generate the triggering of pyrotechnic devices with a technical destination in the automotive field containing pyrotechnic articles of the P1 category, is carried out for each piece of equipment depending on the phases of the technological process of their manufacture. The protection against the accidental initiation of pyrotechnic devices intended for equipping auto vehicles is of particular interest for occupational safety in the manufacturing process of these types of products, because their triggering can endanger the life and health of workers as a result of the uncontrollable effects of functioning, with the generation of thermal and dynamic effects, as well as the emission of toxic reaction products that can affect the human component and/or destroy the work space. The paper highlights the way to analyse the risk of accidental initiation of pyrotechnic devices actuator type from the P1 category, using the latest generation technical-scientific tools in order to computerize the effects following their untimely triggering and establish the safety distances in relation to the amplitude of the degree of damage to the human component, respectively the destruction caused to the work space. In the case of pyrotechnic articles from category P1 type pyrotechnic actuator, the main risks of their accidental initiation are determined by the following technical factors: the production of an electrical discharge greater than 25 KV, the generation of a current with an intensity greater than 0.4 A at the terminals pyrotechnic device, their exposure to a temperature higher than 165°C. The main effects generated after the untimely initiations of these products are determined by: flame, thermal radiation, dynamic pressure waves, projected fragments and hazardous releases of chemical combustion products. Depending on the results obtained following the estimation and assessment of the assessed risks, preventive and countermeasures of a technical and organizational nature are established, in order to secure the predicTab. operations of specific operations with these types of products.

Design and characterization of a pyroshock reduction structure based on local resonance mechanisms

In the spacecraft Pyrotechnic shock process, the explosion generated by the strong shock wave and preload force release of the vehicle structure produces a transient, high-frequency, and high-amplitude shock response, resulting in a harsh shock environment prone to failure or damage to many precision equipment or components on the spacecraft, a fatal impact on the launch mission. This paper designed a local resonance shock mitigation structure based on local resonance theory for the Pyrotechnic shock environment and optimized the parameters of the structure by the genetic algorithm. A Pyrotechnic shock simulation experimental device was built to verify the impact reduction effect of the designed shock reduction structure. This experimental device can well restore the pyrotechnic shock environment. In addition, a finite element simulation model was established, and the impact reduction effect of the protective structure was verified both numerically and experimentally. The experimental and numerical analysis results show that the impact response decays significantly in the structural band gap range with the same transfer path, and the shock response spectrum amplitude decreases 9.8 dB in the 100–10,000 Hz frequency band.

Preparation and properties of a new high-energy metal (W) film/aluminum nitride system energy exchanger electrothermal pyrogenant

In order to improve the safety and energy exchange efficiency of electric thermal pyrotechnic devices, a new energy exchange element technology of high energy metal (W) film/aluminum nitride ceramic was explored by taking advantage of the high thermal conductivity of aluminum nitride ceramic materials. High-temperature co-fired ceramics were used to prepare the new system energy exchangers, and the prototype of the new system energy exchanger of high-energy metal (W) film/aluminum nitride was obtained. Through infrared microscopic test and ignition performance test, the new system energy exchanger of high-energy metal (W) film/aluminum nitride can satisfy the 1A1W5min non-ignition test, and the ignition current of 50% is 2.80 A. The response current of 99.9% is 3.54 A, and the response current of 0.1% is 2.06 A, which provides technical support for the application of a new type of passivated electric thermal pyrogenic product.

Research on the electro-magnetic protection technique of SCB bridge based on vertical punch through PN junction

Pyrotechnic device is the key initiating component of weapon system, and its function reliability will directly affect the triggering of detonation and actuation mechanism. In order to enhance the survival ability of pyrotechnic device in intricate electromagnetic interference environment, it is necessary to carry out in-depth research on the electromagnetic protection technique of pyrotechnic device. In this paper, a new electromagnetic protection circuit based on vertical punch through PN junction device is proposed, which monolithically integrates the circuit with polysilicon semiconductor bridge on a single chip. The Electro-static Discharge (ESD) test was carried out according to the method specified by standard electrostatic standard 500 pF/500 Ω/25 kV, and the ESD capability of the proposed new chip was not less than 25 kV. Compared with the electromagnetic protection circuit by transient voltage suppressor diode based on lateral punch through junction device structure, the new chip increases the effective junction area of PN junction, reduces the current density, and increases the current conduction ability and electrostatic roughness of the diode. The new chip has a larger diode effective junction capacitance, which not only improves the ESD capability but also improves the RF protection capability at the same time.

Evaluation of the effects produced by triggering pyrotechnic articles for automotive use by exposure to various hazardous external stimuli

The object of the evaluation of the risk factors that may lead to the accidental initiation of the semi-finished products containing pyrotechnic articles in the process of handling / use / storage / transport is represented by the estimation and assessment of the risk of initiation / detonation of pyrotechnic devices, based on the quantification of the dangers specific to the operations with these types of products, carried out in various phases of the technological flow, used in the manufacture of electrical circuit breakage subassemblies in motor vehicles. Protection against detonation due to accidental initiation is of particular interest to safety because these detonations endanger the life and health of workers as a result of the uncontrollable effects of deflagration and pressure, the presence of toxic reaction products and the consumption of oxygen from ambient air, which workers must inspire. Accidental initiation / detonation of the pyrotechnic actuator can occur by exposing it to the following dangerous external stimuli: electrostatic charge/electrical discharge – with a potential greater than 25 kV; stray currents when passing a current of 0.4 A through the two actuator initiation pins; temperature – higher than 165 ⁰ C; mechanical shock.

Low-temperature structural deformation and fragmentation of lead styphnate by in-situ experiments and calculation

As one of the most used pyrotechnic composites in spacecraft pyrotechnic devices, the reliability of lead styphnate (LS) in a cryogenic environment needs an adaptability evaluation before the deployment of new deep space exploration programs. Nonetheless, there is a limited understanding of the effects of low temperatures on LS. Herein, we have designed cryogenic storage experiments with a low-temperature in-situ methodology to explore the effects of low temperatures on the properties and performance of LS. By comparing the experimental data before, after storage, and at low temperatures, LS exhibited unique characteristics and failure behaviors at low temperatures than at high temperatures. After storage, the impact sensitivity of LS increased sharply due to particle fragmentation, whilst the flame sensitivity of LS decreased significantly at low temperatures. Employing in-situ powder x-ray diffraction (PXRD) characterization and ignition tests, the low-temperature ignition failure of LS is thought to be closely related to the distortion of the crystal structure of LS, resulting in a “structural shutdown” at −80 °C. Our study disclosed the properties of LS at low temperatures and provided feasible research methods for other energetic materials, aiming to prevent possible future risks and help to establish test standards at low temperatures.

Pyroshock Isolator for Spacecraft Applications

Pyroshock produced by pyrotechnic devices are the most severe shock experienced by spacecraft and its components. In spacecraft pyro devices are used for deployment appendages and mounted on spacecraft with critical electronic equipments placed in their near field and mid field. Attenuation of the pyroshock levels transmitted to these equipments is attempted by providing passive isolator at the base of the pyro devices. The isolator material for spacecraft application is to be space qualified and the isolator dynamics to be uncoupled from spacecraft modes to survive launch loads. The isolator stiffness is arrived based on load characterisation tests done on the damper material and the isolator configuration is adaptable for mounting on spacecraft with restrictions in size, mass etc. Design of the isolator is done based on stiffness to achieve the isolation at high frequencies as well as to survive the launch loads. The shock attenuation of the order of 20 dB at high frequencies is achieved.

A coupled computational framework for the transient heat transfer in the typical pyrotechnic device

Propellant combustion in pyrotechnic devices produces high-temperature, high-pressure gas. The component is moved by high-pressure gas, which subsequently impacts the energy absorber and causes it to compress and deform. The temperature difference between the high-temperature gas and the wall causes transient heat transfer. Propellant combustion, transient heat transfer, and structural response are coupled, but previous studies had to independently analyze them. Therefore, a multi-physical field numerical model is developed based on the commercial software ABAQUS in this paper, which couples energetic material combustion, transient heat transfer, and structural response. In the user subroutine VUAMP, a lumped-parameter model is used to predict the parameter distribution of combustion products. This determines the load applied on the thin-walled tube and the boundary conditions of transient heat transfer. In ABAQUS, the transient heat transfer and structural response are investigated by the direct thermo-dynamic coupling method. The coupling effect between multiple physical fields is realized by real-time parameter exchange. The rationality and accuracy of the coupling model are verified by comparison with the experiment. The results show that the coupling model can effectively simulate the complex coupling process after considering the transient heat transfer and the interaction between multiple physical fields. Taking a pyrotechnic device as the research object, the pressure load accuracy obtained by the coupled model is improved by 5.1%, and the structure response obtained is also closer to the experiment result. At the same time, more characteristic parameters of the structure field and temperature field are obtained.

On pyroshock tests for aerospace equipment qualification: A comprehensive parametric model for the simulation and the design of pyroshock test facilities

Spacecraft and related onboard equipment are subject to strong dynamic loads during the different phases of the missions. In particular, severe high-frequency shocks - mainly caused by the activation of pyrotechnic devices (hence the name "pyroshock") - are transmitted to the entire structure and could cause mission failure and safety-critical damages. Therefore, the verification tests of the aerospace equipment are essential to prove the resistance of the instrumentation to impulsive loads. The requirements for this qualification are usually expressed in terms of Shock Response Spectrum (SRS) acceleration and different launch vehicles cause different SRS. Therefore, the laboratory tests have the objective of simulating the real shock load conditions and - at the same time - being repeatable and safe. For these reasons, the most common test facilities exploit the launch of an impacting object (e.g., hammers or bullets) on resonant plates, interposed supporting the component under test. Recently, many studies have focused attention on the development of numerical analyses to predict the shock responses of these structures, given that their calibration is currently conducted with empirical techniques and involves considerable costs and downtime. This work aims to present an effective parametric model both for the simulation of pyroshock tests and for the optimization of the design of test facilities. The novel implementation of an embedded Computer-Aided Design (CAD) modeler – integrated with a Finite Element (FE) solver – and a Genetic Algorithm (GA) optimizer makes the proposed model both accurate and flexible. Precisely its flexibility makes it possible to effortlessly and efficiently satisfy the variable SRS requirements, reducing calibration times and - consequently - entailing remarkable economic advantages. The proposed model is developed entirely in the frequency domain, making it accurate and fast in computational terms. Furthermore, a comparison between the simulated pulse and a real force profile obtained from an impact characterization is presented.

A design of laser pyrotechnic device based on fiber laser detonation

In order to meet the application requirements of high performance, high safety and high reliability of laser explosives in future weapons and equipment, this paper tries to solve the problem of interaction reliability between laser and energetic materials, and studies the interaction law between fiber laser and energetic materials with high beam quality. The principle prototype of all-fiber laser ignition with high beam quality is developed. The interaction between high beam quality pulsed laser and energetic materials was studied. Fast and efficient ignition of pulsed fiber laser based on high beam quality is realized. Compared with semiconductor laser, the output brightness of fiber laser is high and the light energy is concentrated under the condition of the same output power, which is conducive to the instantaneous generation of high temperature hot spot when interacting with the agent, which can effectively improve the ignition efficiency. And the photoelectric conversion efficiency is high, can effectively reduce the energy supply. It is an ideal pyrotechnic device which can improve the safety of weapons and equipment in modern war.

Особливості використання гуми як конструкційного матеріалу під час створення вузлів стикування систем термостатування

Explosive bolts are widely used as actuating devices in the spacecraft separation systems. Explosive bolt body is divided into parts as a result of engagement of the pyromixture placed inside. Activated explosive bolts have negative mechanical effect on the interface elements and sensitive electronic devices installed nearby owing to explosive behavior of the pyromixture combustion, generating shock front with high pressure and velocities, impacts and collisions of the structural units. Cumulative effect of the above factors on the separated objects is called pyroshock. For separation systems with increased requirements to external actions and cleanliness, authors developed a shear explosive bolt or pyrobolt, divided into parts, cutting the body walls in segments, which are set in motion by action of the pressure of gases, released as a result of pyrocartridge activation. The basic sources of pyroshock for these shear explosive bolts with segments are: combustion of pyromixture, internal impacts of structural units against the bolt body; cutting of body wall in segments, release of preliminary deformed interface after activation. Structural solutions are presented to reduce the pyroshock per each of the components. Vibration impulsive loading during pyromixture combustion is reduced by optimization of explosive quantity, finding its minimum to provide the reliable activation of the device. To reduce the impact on the explosive bolt elements and shock front interface the rubber gasket is installed in the path of shock wave distribution, partially disseminating and absorbing its kinetic energy. Damper, made of easily deformable aluminum alloy, is also installed to decrease the internal impact of the rod against the explosive bolt body. Functional testing of the device, using the pendulum suspension and measuring separation speed and vibration impulsive loading, showed that body parts of the shear explosive bolt with segments are separated without significant impact loads and discharge of high-temperature gases and debris, providing reliable separation of compartments and units without damaging the sensitive equipment. Obtained values of the mechanical momentum, I = 0,4÷0,7 N•s and shock load spectrum – g-load 1950 g at the frequency range up to 5000 Hz, meet the up-to-date requirements to pyrotechnical devices. Key words: explosive bolt, pyroshock, shock wave, pyrocartridge, high-temperature gases, damper.

Synthesis of Co(OH)F@Al nanobelt array on various substrates for pyro-MEMS

Metastable intermolecular composites (MICs) composed by solid fuel and oxidizer can undergo violent redox reaction with release of huge amount of energy. Integration of MIC with microelectromechanical-system (MEMS) is of particular interest to meet the demand of miniaturization in modern pyrotechnic devices. Meanwhile, fluorine-containing oxidizers are favored in MIC owing to their potential to fluorinate the oxide passivation layer in common elemental fuels. Herein, Co(OH)F was employed for the first time as a novel fluorine-containing oxidizer in Al-based MIC. Vertically aligned Co(OH)F@Al nanobelt arrays (NAs) with tunable morphology were successfully fabricated on a variety of substrates (Si, glass, Ni, Cu, Ti) via a facile hydrothermal synthesis followed by electron beam evaporation. The whole fabrication process is highly compatible with modern MEMS technology. The thermal behavior of pure Co(OH)F and Co(OH)F@Al composites was comprehensively investigated by TG-DSC and a series of ex-situ and in-situ characterization. It was found that, Co(OH)F@Al composites achieved main exothermal reaction before melting of Al regardless of morphology and equivalence ratio. This feature is attributed to the etching of Al2O3 shell by HF released from Co(OH)F which is termed as pre-ignition reaction. To elucidate the effect of micro-structure on the actual specific heat release, we proposed a phenomenological model which can be a reference for future micro-structure design of MIC.

Theoretical Analysis and Numerical Simulation of the Motion of RDX Deflagration-Driven Flyer Plate Based on Laser-Initiated Micro-Pyrotechnic Devices.

Miniaturized laser-initiated pyrotechnic devices have great application prospects in aerospace and modern weapon systems due to their excellent energy output performance and reliability. In order to develop a low-energy insensitive laser detonation technology based on a two-stage charge structure, it is important to deeply analyze the motion law of a titanium flyer plate driven by the deflagration of the first-stage charge (RDX). The effects of the charge mass of RDX, flyer plate mass, and barrel length on the motion law of flyer plates were studied through a numerical simulation method based on the Powder Burn deflagration model. The consistency between the numerical simulation and the experimental results was analyzed using the paired t confidence interval estimation method. The results show that the Powder Burn deflagration model can effectively describe the motion process of the RDX deflagration-driven flyer plate with a 90% confidence level, and its velocity error is ≤6.7%. The speed of the flyer plate is proportional to the mass of the RDX charge, inversely proportional to the mass of the flyer plate, and exponentially related to its moving distance. As the moving distance of the flyer plate increases, the RDX deflagration products and air in front of the flyer plate are compressed, which inhibits the motion of the flyer plate. In the optimum state (the mass of the RDX charge is 60 mg, the mass of the flyer is 85 mg, and the length of the barrel is 3 mm), the speed of the titanium flyer reaches 583 m/s, and the peak pressure of the RDX deflagration reaches 2182 MPa. This work will provide a theoretical basis for the refined design of a new generation of miniaturized high-performance laser-initiated pyrotechnic devices.

On the question of the criminal legal concept of an explosive device

The subject of the study is problematic issues related to the concept of the subject of the crime under Article 222.1 of the Criminal Code of the Russian Federation, namely, an explosive device, and with the assessment of the degree of public danger of objects that have the design features of explosive devices, but are not legally such. To resolve the issue of the relevance of the subject to the subject of Article 222.1 of the Criminal Code of the Russian Federation, as a rule, an explosive examination is appointed, however, expert terminology is based on special knowledge in the field of forensic explosives and differs somewhat from legal. The purpose of the work is a detailed study of these inconsistencies in the concepts of an explosive device, an assessment of the degree of public danger of a number of objects that are not explosive devices, but contain an explosive charge and have other design features of explosive devices. In the course of the study, methods of observation, comparison, analysis of expert practice, current legislation and scientific literature were applied. The novelty of the research lies in the study of the concept of an explosive device both from a legislative point of view and from the point of view of forensic explosives. According to the results of the study, the necessity of changing the legislative approach to the concept of an explosive device, and revaluation of the degree of public danger of imitation and pyrotechnic devices is argued. Recommendations have been developed to bring the measures of the criminal law fight against illegal trafficking of explosives and explosive devices in line with modern requirements. The results of the work can be used both in the judicial interpretation of the subject of the crime provided for in Article 222.1 of the Criminal Code of the Russian Federation, and directly by the law enforcement officer when evaluating the conclusions of the explosive expertise.

Research on the Interior Ballistic Design of a Low Impact Ejection Explosive Bolt

Aiming at the comprehensive functional requirements of the connection, unlocking, boosting and impact reduction of the pyrotechnic separation device, a low impact ejection explosive bolt was designed, and its action process was analyzed. The internal ballistic simulation program is used to analyze and study the matching characteristics of internal ballistic input parameters and output parameters. The verification shows that the design is reasonable and accurate. This study provides a reference for the design of similar low impact ejection explosive bolt.

Numerical simulation of actuation processes and decoupling pyroshock of a pressure cartridge-type pin puller

In this study, a finite element model of a pressure cartridge-type pin puller is used to simulate the actuation process and predict the actuation shock using the deflagration equation of state and the fluid-structure coupling algorithm of the MSC/Dytran. The established model is validated by comparing the simulation results with the experimental results for pressure and actuation shocks. Based on the established finite element model, the contribution of the four shock sources to the actuation shock is quantitatively decoupled by changing the state of the pin puller. The results demonstrate that the maximum shock caused by the piston impact was 7454.33 G in the analysis frequency range of 500 Hz–10 kHz. The piston impact was the primary contributor to the actuation shock, accounting for approximately 80.80%. The contribution of the shock caused by payload release was approximately 18.56%. However, the total contributions of the shock generated by the pyrotechnic charge combustion and piston cutting off the shear pin were less than 1%. The conclusions of this study can provide a reference for the structural and shock-reduction design of pressure cartridge-type pyrotechnic separation devices.