Trinitrotoluene Research Articles

Numerical analysis of reinforced concrete buildings subjected to blast load

AbstractThis study deals with a three‐dimensional (3D) nonlinear finite element (FE) analysis of two reinforced concrete (RC) buildings. The first is a three‐floor flat slab building without shear walls. The second is a three‐floor flat slab building with four shear walls. The blast load has been simulated using the coupled Eulerian–Lagrangian (CEL) technique found in the FE software Abaqus/Explicit. Concrete behavior has been modeled using the Johnson–Holmquist damage model (JH‐2) with 3D eight‐node reduced Lagrangian integration elements (C3D8R). The reinforcement steel has been modeled using the Johnson–Cook (JC) plasticity model and the JC computational fracture model with beam elements (B31). Trinitrotoluene (TNT) explosive material has been modeled using the Jones–Wilkins–Lee (JWL) equation of state (EOS) with eight‐node reduced integration Eulerian elements (EC3D8R). Air has been modeled using the EOS for ideal gas with EC3D8R elements. TNT charges of 20, 100, and 1000 kg with standoff distances of 2, 5, and 10 m have been used in the analysis. An analysis has been performed to study the two RC buildings' deformation, stresses, and damage. The results showed that small TNT charges of less than 20 kg with a standoff distance of more than 10 m had almost no effect on the two buildings. Also, huge TNT charges of more than 1000 kg with a standoff distance of less than 10 m had a catastrophic impact on the two buildings.

(2-Vinyltetrazolyl)furoxans as New Potential Energetic Monomers.

A regioselective approach toward the synthesis of a set of new (2-vinyltetrazolyl)furoxans as potential energetic monomers has been realized. All target energetic materials were thoroughly characterized by spectral and analytical methods. Moreover, crystal structures of two representative heterocyclic systems were studied by single-crystal X-ray diffraction. Prepared high-energy substances have high combined nitrogen-oxygen content (63-71 %), high enthalpies of formation and good detonation parameters (D: 6.7-7.8 km s-1; P: 18-28 GPa). Mechanical sensitivities of the synthesized vinyltetrazoles range these explosives from highly sensitive to completely insensitive. Using calculations of molecular electrostatic potentials (ESP), structural factors influencing the impact sensitivity were revealed. Overall, newly synthesized (2-vinyltetrazolyl)furoxans are of interest as promising energetic monomers due to the presence of the vinyl moiety and explosophoric heterocyclic combination, while their performance exceeds that of benchmark explosive TNT.

The triple point path prediction model based on geometric method

ABSTRACT The pressure-time relation in the shock flow field of a near-earth air blast is complex. The triple point (TP) path is the physical boundary between the free and non-free shock flow fields. Accurately predicting the TP path is the basis for studying the evolution law of the reflection flow field and the guarantee of effectively assessing the damage power of the warhead. Based on the assumption that the Mach stem center is on the projection point of the blast center on the ground, the TP path calculation method was constructed by the geometric relationship. The unknown coefficients were solved using the existing TP data and the least square method. The TP prediction model proposed was compared with the existing ones on the calibration, new numerical simulation TP, and the measured real blast datasets. The error of the new numerical simulation TP data is within ±15% of the real value. The results show that the TP path prediction model proposed performs better. Most of its prediction results are within ±20% of three datasets compared to other models for the working conditions with the scaled height of burst from 0.397 to 2.777 m/kg1/3 and the horizontal scaled distance within 10 m/kg1/3 in the conventional cylindrical TNT explosion with the length-diameter of 1 in the air. The reliability of the prediction model is verified.

Polymeric Hydronitrogen N4H: A Promising High-Energy-Density Material and High-Temperature Superconductor.

Solid nitrogen-rich compounds are potential high-energy-density materials (HEDMs). The enormous challenge in this area is to synthesize and stabilize these energetic materials at moderate pressure and better under near-ambient conditions. Here, we perform an extensive theoretical study on hydronitrogens by the reverse design method considering both energies and energy densities. Four hydronitrogens with different stoichiometries, that is, N4H, N3H, N2H, and NH, are found to be stable at pressures of about 80-300 GPa and metastable with pressure releasing to ambient pressure. The energy densities of these hydronitrogens are about 5.6-6.5 kJ/g and 1.3-1.5 times larger than that of trinitrotoluene (TNT). Most importantly, the Pbam phase of the N4H compound is an excellent high-temperature superconductor with a Tc of 37.7 K at 72 GPa. The present findings enrich new phases of hydronitrogens under high pressure and characterize their structural and energetic properties and superconductivity, which offer crucial insights for further design and synthesis of exceptional materials with high energy density and high-temperature superconductivity.

Non-linear FE investigation of subsurface tunnel with gfrp protection against internal blast

The contribution of subsurface tunnels in the present time is imperative. However, in the past few decades they have become a target to explosives and terrorist attacks. Considering the strategic importance and susceptibility of tunnels in case of internal explosion, the blast mitigating design has become very critical. In this work, a novel concept involving the use of glass fiber reinforced polymer (GFRP) layer to strengthen the reinforced concrete (RC) tunnel lining against these incidents has been introduced. Metro underground tunnels exposed to internal blast with two different surrounding soil conditions are investigated. The analysis is done using explicit 3D-Finite Element (FE) method. A comparative study towards the damage due to explosion of different trinitrotoluene (TNT) charges is executed. It is observed that the application of GFRP layer reduces the displacement and stress values at key points in tunnel and ground surface under different explosive charges and soil conditions. Also, there is a reduction in the tunnel damage as well as the risk of long-term geotechnical effects in soil. Thus, GFRP may be effectively utilized as an additional layer to improve the resistance of RC tunnel against blast instead of designing an uneconomical rigid structure. Consequently, the present study contributes towards the safety and blast mitigation design of RC tunnels.

Emission rates, ALOHA simulation and Box-Behnken design of accidental releases in butyl acrylate tank - case study

Abstract The leakage of hazardous compounds in chemical industries has always been one of the factors threatening workers, plants, and the environment. Among them, butyl acrylate is one of the most harmful materials that are widely used in chemical plants. In the present study, a butyl acrylate tank located in a real tank farm in Kocaeli-Turkey was analyzed for the examination of emissions and trinitrotoluene (TNT) equivalent explosion model of the vapor cloud. Areal Locations of Hazardous Atmospheres (ALOHA) program was used to define threat zones of butyl acrylate leakage based on different scenarios, such as a leakage from the tank without fire, burning as a jet fire, and also burning as a fireball during Boiling Liquid Expanding Vapor Explosion (BLEVE). In addition, since the most important parameters that enhance the effects of explosion and the spread of volatile organic compounds (VOCs) are wind speed, filling ratio of the tanks, and temperature, the interaction of these parameters on the threat zones and the highest threat zones of explosions were investigated using the Box-Behnken experimental design and one-way Analysis of Variance (ANOVA), respectively. As butyl acrylate, one of the most dangerous chemicals for industrial facilities, and its explosion effects have not been studied so far, it can be safely mentioned that this paper representing the first study in the literature is highly original and novel.

Influence of honeycomb core height on the blast mitigation performance of sandwich panel

Explosive attacks are a major terrorist threat that is increasing day by day. Honeycomb sandwich panels have a high capacity to absorb energy under blast loads and are very popular for protective structures against blast. Honeycomb sandwich panels are designed with various design parameters. The investigation of the blast mitigation performance of the sandwich panels through experiments is very costly as well as a hazard for both the environment and people. However, in this present work, the blast performance of the square honeycomb sandwich panels (SHSPs) was investigated numerically by dynamic explicit analysis using ABAQUS 6.14. The SHSPs with equal or unequal mass were modelled with 51 mm, 61 mm, and 71 mm core heights to analyse their effects on the face sheet deflection and energy absorption. The blast resistance characterization was carried out at 1 kg to 3 kg of trinitrotoluene (TNT) explosion for a 0.1 m stand-off distance after the mesh convergence and validation study. The simulation results show that increasing the core height improved blast resistance by reducing back face deflection and increasing energy absorption by the core. The SHSPs with a 71 mm core height outperform the other modelled sandwich panels and can be utilized for armoured applications.

Attenuation of blast waves from an intense explosion in dusty gases: a case study

An intense explosion in dusty gas is analyzed considering the Beirut ammonium nitrate explosion of 2020 as a case study. The data available from various sources for the Beirut explosion are used to determine the energy released and the possible reduction in damage radius if there were additional dust particles in the atmosphere. The relationship derived in our previous article ( Proc. R. Soc. A 476 , 2020) between the blast radius and the time of arrival of the shock seems quite accurate, and here the energy released by the explosion and the mass of trinitrotoluene (TNT) equivalent based on energy considerations and blast damage are estimated for dusty gases. These estimates depend on Γ , the ratio of specific heats of the dusty gas mixture. The hydrostatic overpressure and dynamic pressure are calculated from previous results by using the data available. The variation of the three dust parameters in the atmosphere, i.e. (i) mass concentration of dust particles ( k p ) , (ii) specific heat ratio ( β ) , and (iii) density ratio ( G ) , gives the estimated TNT equivalence as ≈ 0.1 kt to 2.5 kt up to a distance of 500 m. Enhanced decay and reduced pressure is evident for dusty gases with appropriate dust parameters.

Super‐Droplet Method to Simulate Lagrangian Microphysics of Nuclear Fallout in a Homogeneous Cloud

AbstractNuclear detonations produce hazardous local and global particles or fallout. Predicting fallout size, chemical components, and location is necessary to inform officials and determine immediate guidance for the public. However, existing nuclear detonation fallout models prescribe the particle size distributions based on limited observations. In this work, we apply the super‐droplet method, which is a numerical modeling technique developed for cloud microphysics, to simulate size distributions of particles in a mushroom cloud formed post‐detonation of a nuclear device. We model fallout formation and evolution with homogeneous nucleation and condensation of a single species and a Monte Carlo coagulation algorithm. We verify the numerical methods representing coagulation and condensation processes against analytical test problems. Additionally, we explore several scenarios for the integral system mass and yield in equivalent kilotons (kt) of TNT (trinitrotoluene). The fallout size distribution median diameter dpg follows a scaling law based on the integral system mass mv0 kg and yield Y kt: nm. We test the effect of cloud turbulence, enhanced nucleation and growth, and vapor volatility with a sensitivity study. The range in median diameter predictions for simulations of historical tests performed over the Pacific encompass the measurements of particles sampled from the cloud caps. Predicted median particle size ranges up to 217, 123, 86, and 35 nm for historical tests with yields of 0.2, 0.7, 2, and 10 Mt, respectively. This work can be expanded in many different directions to build a more predictive model for fallout formation.

Trinitro‐orcinolate and Trinitro‐resorcinate – Sensitivity Trends in Nitroaromatic Energetic Materials**

Abstract5‐Methyl‐2,4,6‐trinitrobenzene‐1,3‐diol (trinitro‐orcinol, H2TNO) as a close structural relative to the well‐known energetic materials trinitroresorcinol (styphnic acid) and trinitrotoluene (TNT) is prepared in high purity and analyzed concerning its vapor pressure using the transpiration method. Several energetic coordination compounds (ECCs) of its respective anion were produced and compared with structurally close styphnate complexes to give an insight into physiochemical trends of the ECC. The synthesized compounds were further analyzed by elemental analysis, IR spectroscopy, differential thermal analysis and low temperature X‐ray diffraction analysis. To classify the reported compounds among the energetic materials, they were tested for their sensitivities towards mechanical stimuli such as impact, friction and electrostatic discharge as well as their behavior towards flame.

Numerical simulation of the effect of water-decoupling charge blasting on reservoir permeability enhancement

In the development of deep resources, blasting fracturing technology is one of the most effective means to improve the permeability of otherwise low-permeability reservoirs, while the pressure rise time of shock wave and the charge structure are the key factors affecting the blasting effect. Thus, this paper first deduces a formula for the pressure rise time, based on which, the blast-induced damage evolution is numerically simulated, and the numerical result is consistent with the existing studies, which verifies the feasibility of the formula. In addition, the influence of decoupling coefficients (K) of different types of explosives (i.e. TNT, emulsion, and ANFO explosives) on the damage range of reservoir blasting is studied. It is found that under the blasting of different types of explosives, the damage evolution law of the reservoir is different, and appropriate explosives should be selected in combination with rock stratum parameters in actual construction. Finally, the increase in permeability and the drainage effect of the reservoir after blasting are quantified by numerical simulations. It is demonstrated the average permeability increment of the reservoir under the action of TNT explosive is the largest, which is 3.08 (K = 4), while that under the action of emulsion explosive and ANFO explosive are 1.49 (K = 2) and 1.17 (K = 3) respectively; and the changes in reservoir permeability and drainage volume are coherent with the range of damage; the greater the range of damage, the greater the reservoir permeability and the greater the drainage efficiency.

An interface to provide the physical properties of the blast waves from surface-burst TNT explosions

An interface to provide the physical properties of the blast waves from surface-burst TNT explosions

The Effect of TNT Mass and Standoff Distance on the Response of Fully Clamped Circular Aluminum Plates to Confined Air-Blast Loading

An experimental and numerical investigation was conducted to examine the response of fully clamped, 2-mm-thick, 255-mm-diameter, circular plates of Aluminum 2024-T3 to confined air-blast loading. The plates were subjected to pressure loading generated by detonating varying charge masses of trinitrotoluene (TNT) at several axial positions in the chamber. In the first set of experiments, the charge mass was varied from 14 g to 50 g and the charge was located at the center of the chamber. In the second set, all charges were 15 g in mass, but they were detonated at different standoff distances. The experimental parameters for the explosive charge mass and the standoff distance needed to produce initial cracks in the aluminum plates as well as the permanent deflections of the uncracked plates were determined. The tests were simulated using the Arbitrary Lagrangian-Eulerian capability in the LS-DYNA commercial finite element program. The numerical simulations generally produced a good match both to the onset of fracture and the permanent displacements in the test plates. The presence of afterburn was demonstrated in a separate test where no oxygen was present, and a better match of the permanent displacements produced by the smallest charges was obtained when afterburn was included in the simulation. The finite element mesh, analysis approach, and blast modeling methodology can be used as a design or evaluation tool for the analysis of potential blast events in full-scale aircraft.

Ballistic penetration of deforming metallic plates: Experimental and numerical investigation

A combined experimental and numerical investigation is carried out to study systematically the ballistic performance of a metallic plate that deforms continuously under pre-imparted impulsive loading (e.g., due to TNT explosion) before being impacted by a projectile. First, based on a novel experimental method, ballistic impact test of a deforming thin steel plate is performed via an one-stage gas gun; as benchmark, ballistic impact test of a static (non-deforming) thin steel plate via a two-stage gas gun is also performed. Results show that deforming has significant influence on ballistic performance of metallic plates in terms of perforation mode and ballistic limit. Then, based on three-dimensional finite element simulations that are validated against experimental measurements, physical mechanisms underlying the deforming effect are explored. The effects of pre-imparted impulse, the shock resistance of target plate, and the nose shape of projectile on the ballistic performance are also quantified. It is demonstrated that deforming leads to changes of the projectile-target system in three aspects: providing initial kinetic energy to target, changing plastic deformation in dished region, and altering shear force during perforation. The interaction of these three aspects dictates the ballistic performance of a deforming target plate. The results are employed to carry out anti-penetration design for deforming steel plates.

Investigation on influence factors about damage characteristics of ice sheet subjected to explosion loads: Underwater explosion and air contact explosion

Ice blasting efficiency is greatly influenced by many factors of explosives. This study aims to investigate the laws of the damage characteristics of the ice sheet influenced by explosive factors. Fully-coupled numerical models of underwater explosions for ice-breaking were established based on the experimental test, and the numerical results were in good agreement with the experimental results. The damage characteristics of ice sheets subjected to underwater and air contact explosion loads were thoroughly investigated by changing explosive types, explosive shapes, and the length to diameter ratios of cylinder charge. The results demonstrate that high-energy explosives, such as HMX and OCTOL explosives, can result in more serious damage to the ice sheets than the explosion of TNT, FEFO, PBX9010, and TETRYL explosives. A cylinder charge can be suggested to improve the efficiency of ice-breaking owing to its adjustable length to diameter ratios. The underwater explosion type is preferable to the air contact explosion for ice-breaking owing to the combined action of shock wave and bubble loads. The prediction formulas for the failure diameters of the ice sheets are proposed based on dimensional analysis, which provides a reference for ice-blasting engineering.

Effects of Cover Depth and Rock Type on Dynamic Response of Road Tunnels Against Internal Explosions

Dynamic response of road tunnels against internal explosions can vary depending on the types and cover depths of surrounding rock mass. However, the influences of cover depth and rock type on dynamic response of road tunnels under internal explosions are very less investigated. Based on the calibrated numerical model of road tunnel, the present study investigates the dynamic response of an arched road tunnel subjected to an internal Boiling Liquid Expansion Vapour Explosion (BLEVE) and its equivalent TNT explosion under varied cover depths and different rock types. The results indicate that the increment of the cover depth can reduce the lining response (e.g., strain energy and damage) against the internal BLEVE. However, beyond a certain cover depth, the TNT explosion-induced lining response (e.g., strain energy) escalates with the increased cover depth due to the enlarged rebound deformations of the lining with the increased in-situ stress. In addition, the rock mass with better mechanical properties is beneficial to reduce the tunnel response under the internal BLEVE but leads to more severe tunnel response under the internal TNT explosion. Using equivalent TNT explosion loads may not give reliable predictions of tunnel responses subjected to BLEVE loads.

Gurney model for non-standard cylinder with increased wall thickness and its application in aluminized explosives

To meet the requirements of an aluminized explosive cylinder test with a longer energy release time, a non-standard cylinder structure with a larger wall thickness was designed, which can not only extend the effective expansion time of detonation products but also avoid a great increase in the test charge mass. The non-standard cylinder was filled with TNT explosives for its relatively stable Gurney energy, and the experimentally generated parameters were compared with those of Φ50 and Φ100 mm standard cylinders. Based on this, a more accurate Gurney Model for Non-Standard Cylinder (GM-NSC) was proposed taking into account the influence of shell deformation and axial movement of detonation products compared with the traditional Gurney model. The analysis results show that the proposed GM-NSC model curve is suitable for both non-standard and standard cylinders. Finally, the method was applied to DNAN-based aluminized explosives, and the experimental results show that the method can characterize more thoroughly the effect of the detonation product expansion enhanced by the rapid reaction of aluminum powders.

A Review on Residual Solid Propellant Disposal Methods Using HRIM, RISK Score Matrix, Safety Consequence Analysis and Environmental Impact Analysis

Introduction: Solid propellants are high energetic materials used for Launch vehicles and military applications. During solid propellant processing residual propellant generates due to less pot life, machining for insulation lining, scaled and sub scaled trials for mechanical and ballistic properties prediction. A conventional method for disposal of residual propellant is open-air burning; other alternate methods in the literature are incineration, wet air oxidation and molten salt destruction. Methods: Hazard assessment is carried out for the disposal methods both conventional and alternate. Preliminary hazard analysis (PHA), Hazard Risk Index Matrix (HRIM), Risk Score Matrix and as low as reasonably practicable (ALARP) are used to assess the Hazard. Results: Based on the study and calculations Open air burning is having less risk score and medium level safety risk acceptance and tolerable risk which can mitigate. Open-air burning is the safest, efficient and cost-effective way to dispose of the high energetic material but the disadvantage of this method is environmental pollution, high temperature and toxic gases exposure to fire personnel. Based on safety consequences analysis, the 1 gram of solid propellant is found to be 1.308 grams of Trinitrotoluene (TNT) equivalency, and one-time open burning creates 3.822 KPa overpressure on the atmosphere where minimum overpressure to create damage effect is 5 KPa. Conclusion: The environmental impact analysis for disposing of solid propellant gives information about different pollutants, their concentrations in the atmosphere at different altitudes and their impact. Solid propellants are hazard reactive materials they were the one exception under the Resource Conservation and Recovery Act (RCRA) that controls the destruction of hazardous waste.

Doped silica sol layer coatings on evanescent field fiber Bragg gratings for optical detection of nitroaromate based explosives

Evanescent field etched fiber Bragg gratings (eFBG) were prepared with doped and non-doped nanoporous silica sol coatings for optical detection of the nitroaromatic explosives 2,4-dinitrotoluene (DNT), 1,3-dinitrobenzene (DNB) and trinitrotoluene (TNT). We used 3-aminopropyltrimethoxysilane (APTMS) and tetrabutylammonium hydroxide based receptors (TBAH, C16H37NO) as dopants in order to increase the specific identification of the nitroaromates. In nitroaromatic trace gas atmosphere the induced wavelength shift of the Bragg reflection signal was highest for the sensor with TBAH-doped silica sol receptor coating. Within the first two minutes during exposure the change of the signal intensity, reflecting the adsorption dynamics of the nitroaromatic explosives, was most significant and characteristically depending on the type of receptor dopant used. The cross sensitivities of the sensor with TBAH-doped silica sol receptor coating with four common solvents like acetone, ethanol, 2-propanol and tetrahydrofuran (THF) in comparison to the sensitivity of the tested explosives was more than six orders of magnitude (106) lower than that of solvents, indicating a very high selectivity of the sensor. By applying a simplified diffusion model correlated to a series of measurements with different distances to the target we estimated the limit of detection for a sensor coated with TBAH doped silica sol with 35.8 ± 0.9 ppb for DNB and 140.2 ± 1.8 ppb for DNT in air at room temperature. Using a more etched FBG (but mechanically less robust) sensor we were able to detect TNT as well at concentrations about 5 ppb at room temperature in air. A major result of our investigations was to demonstrate, that the nanoporous silica sol host matrix is suited for fast adapting with low technological effort the affinity of the receptor coating for silica-based evanescent field sensors. For future applications a set of sensors of silica-sol coatings with different dopants in combination with pattern recognition of the sensor signals could be used for clear identification of explosives.

Cluster of Hexamolybdenum [Mo6Cl14]2- for Sensing Nitroaromatic Compounds.

This contribution describes a novel method for the detection of trace amounts of trinitrotoluene (TNT) using a cluster of hexamolybdenum with general formula [Mo6Cl14]2–. The molybdenum cluster was characterized by UV–visible, FT-IR, and fluorescence techniques, and the synthesis was efficient and reproducible. The evaluation of the molybdenum cluster by TNT detection was perfomed by fluoresecent measurements, and the results were interpreted by the Stern–Volmer equation, obtaining KSV values of 2.9 × 105 and 1.6 × 104 M–1 in different concentration ranges. Further, the results suggest that at TNT concentrations higher than 4 × 10–5 mM (0.01 mg L–1) it is possible to measure the quenching of the cluster fluorescence. The DFT calculations indicate that the contribution of the TNT in the active lowest unoccupied molecular orbitals that are involved in the higher intensity transitions in the complex cluster–TNT are significant. This situation differs from all the luminescent [M6X8L6]2– clusters (M = Mo; X = facial bridging ligand, and L = labile axial ligands), where most of the closely spaced excited states are located in the {M6X8}q+ core. Thus, the TNT switches off the cluster luminescence. The approach using a [Mo6Cl14]2–-based fluorescence sensor has the potential to be a sensing technology for the detection of nitroaromatic explosives.