Explosive Impact Research Articles

An overview of impact resistance of auxetic lattice structure

Auxetic materials have many advantages in strength and energy absorption, which have become a research focus of scholars at home and abroad. It’s of great significance to ship protection structure design that researching deeply on auxetic lattice structures. According to the unique properties of auxetic lattice structures, this paper mainly introduces the research status of the impact resistance mechanical properties of the new structure. The research status of low-speed impact, high-speed projectile impact, and explosion impact in the auxetic lattice structures is described from three aspects: theoretical, experimental and simulation studies. The research status of in-plane impact at medium and low velocities, explosive impact and projectile penetration is expounded. The effects of geometric parameters and impact velocity on deformation modes and energy absorption of structures are also analyzed. Finally, summarize the article and point out the contents in the future.

Influence of wire parameters on the formability of DP600 steel sheets during wire explosion impact forming

The acoustic pulses caused by the underwater wire explosion can be used to apply work on the surrounding medium. This work designed a set of adjustable wire explosion impact forming tooling to investigate the influence of wire parameters on the formability of DP600 steel sheets. The results obtained based on the current experimental conditions showed that a longer wire length mainly played a positive role in improving the energy utilization rate; a larger lifting height weakened the disadvantage of uneven distribution of pressure caused by the explosion of metal wire, and decreased the difference between the radial pressure and the circumferential pressure of the fractured elements, causing the limit strain pair to be closer to the equi-biaxial tensile strain path and increasing the limit dome heights of the tested specimens. Under the conditions of optimal wire length of 45 mm and lifting height of 37 mm, the limit dome heights and the major strains of the tested specimens were increased by 10% and 20%, respectively, as compared with quasi-static specimens; and the energy utilization rate was improved by 30–50% as compared with other combined wire parameters. The numerical simulation reproduced the dynamic deformation process of tested specimens and showed that the maximum effective strain rate was 1740/s, which was 106 times of that during the quasi-static hydraulic bulging process. The microstructural characteristics showed that under the action of high-speed impact load, the grain size of the tested specimen was reduced by 80%, as compared with that under quasi-static condition.

Study on the influence of the preformed hole size characteristics on the dynamic response of the cylindrical shell under blast loading

The structural response of a cylindrical shell with pre-formed holes subjected to explosive impact loading can be efficiently modeled using the ALE coupling model. The damage process and measurement of point deflection were analyzed based on the results of simulation. Results demonstrated that the pre-formed holes on cylindrical shells will destroy their structural strength. This finding will easily lead to stress concentration, which may affect the damage process and decrease the anti-blast ability of cylindrical shells subjected to explosive impact loading. The pre-formed holes can reduce the load area and weaken the effect of impact loading. Change in hole spacing will influence these factors and affect the deformation of cylindrical shell. The location of the break is different when the distance between the holes is different.

Influence of Fluid in Dynamic Calculation of Thin-Walled Cylindrical Tanks by Means of Calculating Added Masses of Fluid

This paper presents the exact solution for the problem of the added masses of fluid, oscillating inside a cylindrical tank. A thin smooth cylindrical shell of finite length, filled with the ideal incompressible fluid that is subjected to transient dynamic load (it may be an earthquake, air explosion impact, etc.), is taken as a design model. In this case, the shell of a tank becomes a part of the oscillating process along with the fluid stored inside. The shell bending equation (stipulated by the membrane theory of shells) is taken as a design model for this case. In this equation, the shell deflection is expanded into Fourier series by oscillation modes, and the velocity potential takes the form of the Laplace’s equation. Fluid’s inertial reaction to the shell motion is covered by the shallow water theory, which is specified by the boundary free surface conditions and the influence of the tank hard bottom. These mathematical expressions of the shell response to the external transient impact are solved by the Bubnov–Galerkin method with the transformation of the initial relations into a system of ordinary differential equations, which include expressions for determining added masses of fluid by oscillation modes of the elastic shell.

Explosion impact strength calculation and failure analysis of glass fiber-reinforced composite pipe

The investigation of failure analysis of the explosion impact strength of glass fiber-reinforced composite tubes was presented in this paper. Scanning electron microscopy was used to perform morphological observation and analysis of the failure cracks of a composite tube under ultra-high-pressure explosion impact. The main failure mode was brittle fiber fracture. Theoretical calculations and numerical simulations were used to analyze the deformation displacement and stress and strain of the composite tube under the impact of ultra-high pressure explosion. The boundary conditions obtained were 49.9 MPa as the minimum failure internal pressure and 0.0782 mm as the radial limit displacement.

Limitations on seismic effects of technological explosions in the combined development of the Sarbai deposit

The issue of joint production of drilling-and-blasting operations (DBO) is acute in the combined field workings with the condition of underground mining in the edge massif of the pit walls. Normally, the underground mine construction begins with the quarry depth approaching the end marks. In this situation, even if there is any volume for wall cutback, it is very insignificant and blasting works come closely to the limit circuit of the quarry, behind which the protected massif is located and underground workings is supposed to be carried out in the future. The main task in carrying out DBO under such conditions is to maintain the stability of this massif. Timely explosion shielding and the creation of contour fracture surfaces by applying controlled blasting reduce the negative explosion impact on the edge, yet do not always prevent the stress waves spread across the massif caused by seismic effect. Therefore, limiting the explosion seismic action in the border zone is as important for the massif stability as the professional pre-splitting.

On the issue of defining safe distances and overpressure under impact of shock air blast wave (Magnesitovaya mine)

As the depth of mining increases, attention to the preservation of mine workings and mining blasting is steadily growing. Technological methods of effective mineral development are often limited by dynamic blasting impact causing short-period fluctuations in the rock mass. Therefore, correct explosion impact identification, to a great extent, determines effective mining trends. Some results of researches for minimum blasting impact on mining workings are given in the article. Calculation of safe distances and excess pressure at shock air impact of technological explosions on the Magnezitovaya mine personnel was made. The calculation was made for the 15.5 m mine working section, with two conditions of the total section of the mine workings adjacent to the face of 15.5 m and 31 m with distances of 50 m and 100 m. Overpressure was also calculated for a total cross-section of 15.5 m and distances of 150 and 200 m. It was determined that the safe distance for people under overpressure conditions at the shock air wave front, depending on breaking schemes, is in the range of 150-200 m. The urgency of this research is to ensure industrial safety of underground mining operations.

Evaluation and safety design of explosion impact strength of refrigerant circuit parts

Evaluation and safety design of explosion impact strength of refrigerant circuit parts

Establishment automatically contour blasting passport for tunnel in AutoCAD by VOLVN 3.0 software

The smooth blasting method has been researched, developed and strongly applied for long-term underground construction, such as principal mining excavations, tunnels and hydroelectric projects... with the main purpose of minimizing the explosion impact on rock and creating a well-shaped boundary. In this research, a software was developed to establish automatically the tunnel contour blasting passport in AutoCAD. Using the software in each blast design model, it is quickly possible to determine number of blastholes, specific charge, specific drilling and drawing automatically of blasting passport in AutoCAD. The interaction between the software and AutoCAD is a new and important factor that helps to complete an automatically closed cycle on computer from introducing parameters to designing blasting passport in AutoCAD, thereby contributing to increase efficiency of production and minimize risks in blasting works.

Analysis of seismic safety assessment procedures for joint development of coal deposits

The safety of mining and exploitation operations is an important factor that allows accident-free mining of mineral raw materials. To achieve this goal, the companies take various measures to reduce hazardous factors, which include blasting and distribution of seismic explosion waves as the phenomenon under consideration. The initial calculation for the reduction of hazardous factors is based on a specially designed procedure. Currently, there are no approved standard methods that could relate to impact of seismic explosion waves on the mounting of mine openings. Various researchers have developed procedures that have certain advantages and disadvantages. This paper presents the methods to assess seismic explosion impact during joint development of coal deposits, which are commonly applied in Russia. It shows the analysis of proposed methods and directions for further improvement of calculations of safe parameters of seismic explosion waves to mine openings.

Hyperspectral imaging of drill core from the Steen River impact structure, Canada: Implications for hydrothermal activity and formation of suevite‐like breccias

AbstractHyperspectral imaging can be used to rapidly identify and map the spatial distributions of many minerals. Here, hyperspectral mapping in three wavelength regions (visible and near‐infrared, shortwave infrared, and thermal infrared) was applied to drill cores (ST001, ST002, and ST003) penetrating a continuous sequence of crater‐fill breccias from the Steen River impact structure in Alberta, Canada. The combined data sets reveal distinct mineralogical layering, with breccias derived predominantly from sedimentary rocks overlying those derived from granitic basement. This stratigraphy demonstrates that the breccias were not appreciably disturbed following deposition, which is inconsistent with formation models of similar breccias (suevites) by explosive impact melt–fluid interaction. At Steen River, volatiles from sedimentary target rocks were an inherent part of forming these enigmatic breccias. Approximately three quarters of terrestrial impact structures contain sedimentary target rocks; therefore, the role of volatiles in producing so‐called suevitic breccias may be more widespread than previously realized. The hyperspectral maps, specifically within the SWIR wavelength region, also delineate minerals associated with postimpact hydrothermal activity, including ammoniated clay and feldspar minerals not detectable using traditional techniques. These nitrogen‐bearing minerals may have originated from microbial processes, associated with oil‐ and gas‐producing units in the crater vicinity. Such minerals may have important implications for the production of habitable environments by impact‐induced hydrothermal activity on Earth and Mars.

Movement Mobilization in the Age of Hashtag Activism: Examining the Challenge of Noise, Hate, and Disengagement in the #MeToo Campaign

This article analyses the challenges faced by the #MeToo campaign, during its first weeks of existence on Twitter. These included the challenges of maintaining its frame, and making a consistent impact in a complex and volatile media landscape. This mixed‐methods study draws on a data set of four million tweets accessed through Twitter's public data interface. It addresses the following research questions: To what degree did the #MeToo campaign on Twitter have a clear focus, and was it able to maintain it? How did the tone of the campaign on Twitter change over time, in terms of the positivity or negativity of expressed sentiments? To what extent were tweets simply reiterated, or instead made the subject of customization and active debate? The article finds that #MeToo quickly started to lose its momentum after the initial and explosive impact, with noise, antagonism, and sloganization increasingly weighing down and diluting the campaign. However, a cross‐platform perspective is needed to grasp a full picture of how hashtag activism functions; including the #MeToo campaign.

EXPLOSION IMPACT SIMULATION METHODS FOR PARALLEL PIPELINE LAYING IN THE SAME DITCH AFTER GAS LEAKAGE

The explosion impact after gas pipeline leakage can be simulated by Arbitrary Lagrange-Euler Algorithm (ALE), Blasting Cavity Theory (BC) and Smooth Particle Hydrodynamics - Finite Element Method (SPH-FEM), each method has its own characteristic. Using the experimental data of Defense Research Establishment Suffield of Canada, it is found that both ALE and SPH can describe the propagation characteristics of detonation waves in a soil well, and SPH-FEM can accurately reflect the compression, cracking and deformation of soil after an explosion. For parallel buried gas pipeline laying in one trench, three pipe-soil explosion models were design based on the mentioned three approaches above, and the same response of pipeline were obtained under the same operating conditions. However, the soil bulging deformation in BC was greater than that in SPH-FEM, the result of the former was more conservative. Moreover, the BC is dominated by the blasting cavity radius, i.e. it cannot be modeled when the radius is larger than the depth of an equivalent explosion. According to the pressure time history curve of the soil unit under the action of detonation wave, the pressure propagation characteristics were analyzed. Finally, the stress and deformation of the attack surface, top surface, back surface and bottom surface of a pipe were analyzed. The research evaluated the advantages and disadvantages of the existing explosion simulation approaches, which can provide technical references for the reliability analysis and risk prevention and control of parallel gas pipelines under extreme disasters.

Impact Modelling of Explosion of Mixture Explosive Charges on the Environment

Abstract The present paper provides the modelling of the explosion of the charges of the traditional (trotyl) and new blended explosive substances: polymix GR1/8 (74 %) + KRUK2 (26 %), compolite GS6, polymix GR4-T10. As a result of the research, it has been established that when using TNT a specific impulse is formed, which is by 40 % more than an explosion of new mixed explosives, and the safe distance from the source of the explosion of such explosives is increased by 25 %–50 %. On the basis of the established dependences of excess pressure, the specific impulse on the type and mass of charge, as well as the distance from the epicenter of the explosion, an engineering method has been developed for calculating dangerous parameters of the explosion impact on the environment.

폭발강화격벽의 초기구조설계에 관한 연구 - 제1보 : 간이 구조 해석/설계 기법 정식화 -

Internal detonation of a warhead inside a compartment of naval vessel can result in serious blast damages including plastic deformation and rupture of the structural members especially bulkhead due to the huge explosive impact pressure, fragments and high temperature flame. To secure watertight integrity and to prevent the domino-type flooding of neighbouring compartments caused by the rupture of bulkheads, it is necessary to develop the structural design technology of Blast Hardened Bulkheads(BHB) which can resist the blast impact pressure of threatening weapons to increase the survivability of naval vessels. This study dealt with the simplified structural response analysis of BHB under impact pressure of confined explosion and aimed to develop the efficient and rational design method of BHB and joint structures which can be applied at initial design stage. The present 1st report dealt with the phenomena of explosive detonation surveying the preceding experimental/theoretical research and the characteristics of time history of blast pressure including the peak value and duration time were examined. And to predict the large plastic deformation behaviors of BHB by the huge blast pressure reasonably, the plastic hinge method including the membrane effects was formulated. It was applied to the simplified structural design equations. The following report will deal with the application and adjustment process of the structural scantling equations to the actual BHB design and verification of validity of them.

Research on dynamic responses of incompletely water-filled cylindrical shell subjected to explosion impact

Numerical simulation on the deformations and damages of incompletely water-filled cylindrical shells subjected to explosion impacts were carried out. The Research shows that the degree of deformation and failure of the incompletely liquid-filled cylindrical shell is smaller than that of the empty cylindrical shell in the same condition. The dynamic response of the completely water-filled cylindrical shell subjected to 75gTNT explosion impact is the same with the one of partially water-filled cylindrical shell. The anti-explosion performance of the 95 % volume water-filled cylindrical shell subjected to 200gTNT explosion impact is better. The explosion direction greatly influenced the dynamic response of partially filled-water cylindrical shell. The dynamic response of a partially water-filled cylindrical shell is approximately the same as that of the fully water-filled cylindrical shell, when the explosion direction is on one side of the water. The results show that internal pressure of water will increase when subjecting to impact loading, the anti-blast ability of tube structure significantly enhanced.

The Dynamic Response of an Experimental Floating Tunnel with Different Cross Sections under Explosive Impact

ABSTRACT Gang, L.; Xiao-jun, Z., and Jian-xun, C., 2018. The dynamic response of an experimental floating tunnel with different cross sections under explosive impact. In: Ashraf, M.A. and Chowdhury...

The V1 (Flying Bomb) attack on London (1944–1945); the applied geography of early cruise missile accuracy

In a 291 day period in the latter stages of WW2 (1944–45) 10,386 V1 cruise missiles were launched against the UK from ground ramps in France and Holland, and from modified He-111 bombers flying off the south and east coasts of England. The attack mainly targeted London and despite a highly effective British campaign of in-flight interception, 2420 V1 missiles (23% of those launched) made explosive impact on the London target area resulting in significant loss of life and massive damage to London's housing stock. Using data from The National Register of 1939 we reconstruct the target geography of London and utilising a vast body of archival data from The National Archives we also reconstruct the V1 impact geography; in doing so we evaluate the accuracy of the V1 attack. Most missiles struck near the centre of the London target in areas of high population density; 40% of the missiles fell on the County of London forming the inner core of the London Civil Defence Region containing 38% of its 1944 population in only 16% of its area. The overall Mean Point of Impact is within 3.5 km of the centroid of the County of London. V1 impact density showed similar Clarke-like distance-decay relations to population density in relation to an assumed Central London aiming point. We also determine the accuracy metrics for the V1 attack. Our results verify the idea that high-resolution accuracy is moot when missile systems with relatively low accuracy are launched against large area targets, such as large cities. Although compared to modern missile systems the V1 was “inaccurate”, we find that the German cruise missile system fulfilled the operational accuracy requirements to achieve its terror and urban damage objectives.

The response characteristics of warhead fragment impact on shielded H6 explosive

For studying response characteristics resulting from fragmentation warhead fragment impact on shielded H6 explosive. H6 explosive has been shielded with Q235 steel, what was impacted for cuboid tungsten fragments at the velocity range of 2000 m/s~2200 m/s launching from 25 mm ballistic gun, with different quality and length-thick ratio of square, The process of impact response was observed by high-speed photography. The maximum diameter and duration of the fireball as well as destruction of shielded H6 explosive were recorded, then corresponding features of shielded H6 explosive were analyzed accordingly. Furthermore, the mechanism of H6 explosive responses was analyzed based on the theory of explosive impact initiation. Results show that it mainly includes combustion, deflagration and detonation for response features of targets, and it has highest probability for deflagration. Adiabatic shear effect was regarded as the functional mechanism, which could produce different response characteristics. Deflagration reactions could be sparked in which of the situations the quality of fragments was no less than 10 g. what's more, the most violent deflagration reactions could be sparked under the certain condition that the length-thick ratio of fragment was about 1.6.

High mechanical performance of AISI304 stainless steel plate by surface nanocrystallization and microstructural evolution during the explosive impact treatment

The surface treatment on AISI304 stainless steel plate was successfully carried out by explosive impacting technique. We have obtained a high mechanical performance and corresponding fine microstructures compared to its base metal by the technique. Experimental results indicate that nanograins (around 30nm of diameter) with random crystallographic orientations formed in the top impacted surface and many deformation bands in the subsurface layers. The explosive impact generated deformation induced martensite (DIM) in the plates, where DIM volume fraction increased firstly and then decreased toward inside. These surface nanocrystallization and microstructural evolution, which can be attributed to the co-actions of the grain-refinement, deformation-bands and phase transformation effects, can enhance surface hardness and mechanical properties remarkably not only near surface but entire plate.