Trinitrotoluene Research Articles

Influence of Altitude and Image Overlap on Minimum Mapping Size of Chemical in Non-Destructive Trace Detection Using Hyperspectral Remote Sensing

The increasing threat of explosives is a serious issue affecting socio-economy of many countries at multiple levels, such as public security, unused arable land, closing of trade routes, isolation of villages, and these act as a hindrance in the development of the country. Activities using explosives have increased in the last two decades making it a global threat that is challenging humanity. In this study, different chemicals such as Ammonium Nitrate (AN), Trinitrotoluene (TNT) and C4 along with soil as the background material were used for trace detection. The aim of this study was to determine an altitude for the sensor and to identify the minimum mapping size of the chemical at which the model can achieve 70% accuracy. To determine the altitude and minimum size of the chemical that can be detected in the acceptable range of accuracy, several experiments were performed in real ground conditions. This study focuses on the applicability of the proposed method in the real world. In the first set of experiments, the altitude of the sensor was varied from 40 cm to 150 cm and the accuracy of the model was determined. From the analysis, it was found that the model achieved more than 75% accuracy at an altitude of 90 cm with an image overlap of 70%. In the second set of experiments, the minimum size of chemical sample was varied from 0.25 cm to 1 cm. The accuracy of the model was more than 70% when the minimum sample size was 0.5 cm or greater. For various altitude determined, the speed of the vehicle was calculated. Therefore, to implement hyperspectral imaging system on the unarmed vehicle for real application, the suggested altitude and speed of the sensor should be around 90 cm and 10.5 cm/s at which detection limit would be equal or more than 0.5 cm with accuracy greater than 70%.

Structure integrity evaluation of gas protective wall for new construction method using strength test and numerical analysis

Gas protective walls are safety elements that can withstand the pressure of fires or explosions caused by gas leaks, thus preventing the spread of explosion damage to other facilities or operators. However, in the new construction or expansion of gas facility rooms in existing buildings, the barrier must often be built even if it does not satisfy the legal standards regarding the accepted construction methods. In these cases, the gas barrier for the existing building should be constructed by the new construction method using chemical anchor bolts. However, no performance evaluation data or reliable engineering verification results are available for the entire gas facility room based on actual experiments. In this study, based on a review of regulations on gas barriers, the protective performances of the new barriers were compared in terms of displacement, rotation angle, rebar strain, and yield value of the concrete surface through actual strength demonstration experiments. Based on these results, the protection performance of an entire gas facility room that could not be constructed and tested in real time was evaluated by a fluid structure interaction (FSI) analysis using the TNT(Trinitrotoluene) equivalency method and three-dimensional AUTODYN.

A Simple Approximate Simulation Using Coupled Eulerian–Lagrangian (CEL) Simulation in Investigating Effects of Internal Blast in Rock Tunnel

The need for faster and safer means of land transportation has increased due to scarcity of land. The number of terror attacks on the underground metro tunnels has increased in the past couple of decades. These events have presented the increased need for blast resistant design of metro tunnels. The stability of underground metro tunnels constructed in the different rocks has been analysed in the present paper. The analysis of impact loading has been carried out using nonlinear finite element technique. The coupled Eulerian–Lagrangian which is an advanced method of modelling for trinitrotoluene (TNT) and air inside the tunnel has been used. The explosive charge has been assumed at the centre of the tunnel having 100 kg mass, and the analysis is carried out for 30 ms of duration. The nonlinear behaviour of TNT has been simulated by using Jones–Wilkins–Lee material model of the equation of state. The nonlinear behaviour of the different rocks, i.e. Quartzite, Quartz-Schist, Sandstone, Shale and Dolomite, has been considered through the Mohr–Coulomb constitutive model. The rock model has 30 m × 30 m × 35 m dimension having an opening of 5 m at the centre of the model. The tunnel has 12.5 m of the depth of overburden and tunnel lining has 0.35 m of thickness. The tunnel lining has been reinforced with steel bars of Fe415 steel grade, and concrete has M30 grade. The rock tunnel constructed in Shale is susceptible to a higher magnitude of damage as compared to other rocks in this paper when exposed to internal blast loading. The Quartzite rock tunnel is the most suitable choice for constructing the blast-resistant tunnel. It has been concluded that Quartzite has higher safety against an internal blast loading caused by 100 kg TNT explosive charge. Heaving has been observed for all the cases on the ground above the location of TNT.

Exposure to dissolved TNT causes multilevel biological effects in Baltic mussels (Mytilus spp.)

Baltic mussels (Mytilus spp.) were exposed to the explosive trinitrotoluene (TNT) for 96 h (0.31–10.0 mg/L) and 21 d (0.31–2.5 mg/L). Bioaccumulation of TNT and its degradation products (2- and 4-ADNT) as well as biological effects ranging from the gene and cellular levels to behaviour were investigated. Although no mortality occurred in the concentration range tested, uptake and metabolism of TNT and responses in antioxidant enzymes and histochemical biomarkers were observed already at the lowest concentrations. The characteristic shell closure behaviour of bivalves at trigger concentrations led to complex exposure patterns and non-linear responses to the exposure concentrations. Conclusively, exposure to TNT exerts biomarker reponses in mussels already at 0.31 mg/L while effects are recorded also after a prolonged exposure although no mortality occurs. Finally, more attention should be paid on shell closure of bivalves in exposure studies since it plays a marked role in definining toxicity threshold levels.

Effects of Explosion Shock Waves on Lung Injuries in Rabbits

The purpose of this study was to explore the damage effects and injury mechanism of free-field explosion shock waves on rabbit lungs. Six free-field explosion experiments, each with 500 g trinitrotoluene (TNT), were conducted as the shock wave overpressure acting on the rabbits was measured. The peak overpressure of the shock wave was 533, 390, 249, 102, and 69 kPa at the respective test points. Damage to the rabbit lungs caused by shock wave overpressure was investigated through observation, anatomical analysis, and hematoxylin-eosin (HE) staining processing. The shock wave overpressure of 69–102 kPa caused mild-to-moderate injury; the shock wave overpressure of 102–249 kPa caused moderate injury; the shock wave overpressure of 249–390 kPa resulted in moderate-to-severe injury; and the shock wave overpressure of 390–533 kPa caused severe injury to the rabbit. Mild, moderate, and severe injuries destroyed some, most, or all alveolar structures, correspondingly, as well as producing partial cell apoptosis. The overpressure damage mechanism primarily involves the collapse and rupture of pulmonary alveolus in the lung tissue. As a novel attempt, the investigation provided here may serve to improve the current shock wave injury mechanism.

Development of a gold nanoparticles-based colorimetric sensor for the indirect determination of ammonium dinitramide and tetryl

Ammonium dinitramide (ADN) is a strong, environmentally friendly oxidizer used in composite solid rocket propellants. As there is no reliable colorimetric sensor for ADN assay applicable to in-field screening, we developed a sensitive and practical sensing method to determine it in the presence of other explosives and possible interferents, based on the detection of nitrite formed from ADN degradation under UV light in a slightly alkaline (i.e. of lower alkalinity than needed to hydrolyze nitramines) solution by a nanoparticle-based colorimetric sensor. The ADN-derived nitrite formed a colored product via a Griess reaction using gold nanoparticles modified with 4–aminothiophenol (4-ATP-AuNPs) along with a coupling reagent N-(1-naphthyl)ethylene diamine (NED) for forming an azo dye. The method used for ADN detection could also be applied to tetryl samples at a different wavelength. The limit of detection (LOD) was 0.012 mg L−1 for ADN and 0.615 mg L−1 for tetryl. Interference effects of energetic materials like trinitrotoluene (TNT), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) and pentaerythritol tetranitrate (PETN) to ADN determination could be overcome. In addition, common soil ions did not adversely affect the nanosensor performance. The developed method was statistically validated against reference voltammetric, UV, and HPLC methods using t- and F- tests.

Insight into the chemistry of TNT during shock compression through ultrafast absorption spectroscopies.

Thin films of trinitrotoluene (TNT) were shock compressed using the ultrafast laser shock apparatus at Los Alamos National Laboratory. Visible (VIS) and mid-infrared (MIR) transient absorption spectroscopies were simultaneously performed to probe for electronic and vibrational changes during shock compression of TNT. Three shock pressures (16 GPa, 33 GPa, and 45 GPa) were selected to observe no reaction, incipient reaction, and strongly developed reactions for TNT within the experimental time scale of <250 ps. Negligible absorption changes in MIR or VIS absorptions were observed at 16 GPa. At 33 GPa, MIR absorptions in the 3000 cm-1-4000 cm-1 range were observed to increase during the shock and continue to increase during the rarefaction, in contrast to the VIS absorption measurements, which increased during the shock and almost fully recovered during rarefaction. At 45 GPa, both VIS and MIR absorptions were strong and irreversible. The intense and spectrally broad MIR absorptions were attributed to short lived intermediates with strong, spectrally broad absorptions that dominate the spectral response. The MIR and VIS absorption changes observed at 33 GPa and 45 GPa were credited to shock induced chemistry, most likely including the formation of a very broad hydrogenic stretch feature. The results from these experiments are consistent with the chemical mechanisms that include O-H or N-H formation such as CH3 oxidation or C-N homolysis.

Lightning mechanical damage prediction in carbon/epoxy laminates using equivalent air blast overpressure

We propose a new, alternative approach to predict lightning mechanical damage in AS4/3506 carbon/epoxy laminates using equivalent air blast overpressure (ABO). Three lightning mechanical damage models are presented: i) the Shock Wave Overpressure (SWO) model, ii) the Conventional Weapons Effects Program (CONWEP) ABO model, and iii) the Coupled Eulerian-Lagrangian (CEL) ABO model. SWOs were determined from classical shock wave theory and the arc channel energy balance equation, and directly applied within pre-described arc channel areas. ABOs in the CONWEP and CEL models were calculated for equivalent TNT explosions and applied over the entire laminate surface. In contrast to the SWO and CONWEP models, the CEL model simulated the coupled fluid-structure interactions of the blast waves with the composite structures. Although the fundamental physics was different, both SWO and ABO induced similar dynamic structural responses and damage behavior within AS4/3506 carbon/epoxy laminates. The fiber and matrix failure, predicted using Hashin's four failure criteria, was not imminent at any of these peak currents. This implies that purely mechanical in-plane damage is unlikely to occur and thus is not a major concern for lightning strikes. This study shows that the ABO models can be used to predict lightning mechanical damage in composite structures as an alternative to a complex SWO model.

Numerical Investigation of Steel Reinforcement Arrangement in Reinforced Concrete Wall Subjected to Blast

Three-dimensional (3D) numerical modelling of inverted-T shape reinforced concrete (RC) wall subjected to blast load is study in this paper. The walls have the same moment resistance with different steel reinforcement arrangements. It is subjected to 13.61 kg Trinitrotoluene (TNT) explosive at 1.21 m standoff distance from the centre. The Arbitrary Lagrange Euler (ALE) solvers coupling approach is employed for the interface analysis between air and structure to simulate the damage mechanism in AUTODYN numerical commercial software. The numerical damage indicator indicated, with mesh dependency assessment, the damage pattern vs experimental appeared precisely on the steel reinforcement grid due to the smaller element size compared to the coarse element used.

Joint Bayesian Inference for Near‐Surface Explosion Yield and Height‐of‐Burst

AbstractForensic capabilities to understand chemical and nuclear explosions are greatly aided by an accurate estimate of explosive yield with uncertainty. The relationship between explosive size and geophysical observations of seismic, acoustic, and optical waves can be exploited to provide an estimate of yield. Any near‐surface yield estimate is complicated by the surface interaction, so an estimate for the explosion height‐of‐burst is necessarily included in the relationship. The relationship dictates a trade‐off between estimates of yield and height‐of‐burst. Fortunately, the surface interaction for each type of observation is different, which breaks the trade‐off, and the inclusion of height‐of‐burst with multiple data types improves yield estimation. We define simple parametric forward models to relate seismoäcoustoöptic observations from a data set of known explosive yields and height‐of‐bursts. The parameters of the models and a prediction for the yield and height‐of‐burst of a new event can then be estimated given new observations via Bayesian inference. We report posterior distribution estimates of the parametric models using a Markov chain Monte Carlo sampling technique. These models are then used to predict the yield and height‐of‐burst of SUGAR, a historical near‐surface nuclear explosion, using its reported historical observations. The reported yield of 1.2 ktonne Trinitrotoluene (TNT)‐equivalent (Department of Energy, 2015) is within the estimated posterior. Yield uncertainty can be estimated from the spread of the posterior, which is between 0.9 and 2.1 ktonne TNT‐equivalent. The posterior for height‐of‐burst has a wider range between 10 m below and 8 m above ground that includes the true height‐of‐burst of 1 m.

Prediction of residual strength of FRC columns under blast loading using the FEM method and regression approach

This study presents a development of empirical equation which can be used for predicting the residual strength of fiber reinforced concrete (FRC) columns subjected to a TNT explosion. For that purpose, numerical investigations on the structural behavior and damage of FRC column under blast loading were carried out. Finite element (FE) modelling of FRC column and TNT explosive charges were built using a robust program, LS-DYNA. Those FE modellings were then verified using relevant, recent test data. A series of parametric analyses was conducted with such various main parameters as section, scaled distance, scaled section, fiber type, and fiber content to investigate the effect of these parameters on the structural behavior and damage of the column under explosion. Some interesting discussions were then presented to thoroughly understand the role of each parameter on the resistant capacity of the column. To develop the empirical equation for predicting the residual strength of the FRC column, Multivariate Linear Regression (MLR) and Multilayer Perceptron for Regression (MLP-R) were employed to generate the fitting models. While the MLP-R showed a superior capacity for estimating the result, MLR, on the other hand, could easily achieve the regression coefficient with fairly good estimation. As a result, a reliable empirical equation that can be used to predict the residual strength of the FRC column in practical design was proposed as an important outcome of this study.

Effects of Concrete Strength and Openings in Infill Walls on Blasting Responses of RC Buildings Subjected to TNT Explosive

The explosions caused by terrorism and/or accidental lead to serious damage and/or collapse in structures, economic losses, and most importantly endanger public safety. The blasting loads that can be larger than design loads are generally neglected in the design stage of civil engineering structures, despite these catastrophic effects. For these reasons, especially strategically important structures such as hospitals, military buildings, and bridges should be designed considering the blasting effects. To this aim, the effects of design parameters such as concrete strength and openings in infill walls on blasting responses of reinforced concrete (RC) buildings are investigated in this study. In situ experimental tests are firstly conducted on a test specimen constructed with brick elements to verify the finite element (FE) model criteria and assumptions. The blasting experiments are performed using 40, 150, and 290 g trinitrotoluene (TNT) explosives. Then, two RC buildings are selected as application, and blasting analyses are done with numerical and empirical methods. FE models of the buildings including structural and non-structural elements are constituted in ANSYS Workbench software. The blasting analyses are carried out with ANSYS AUTODYN software using 100 kg TNT explosives. In the analyses, two different openings in infill walls and six different concrete classes are considered. The blasting pressures, displacements, absorbed and released total energies, and damage ratios are obtained and presented as comparison parameters. The results obtained from the blasting analyses are presented with graphics and tables, comparatively. The study shows that peak pressures and maximum displacements decrease by 22.50% and 32.16% with the increase in concrete strength. Also, it is observed from numerical analyses that openings in infill walls lead to a change of 8.16% in peak pressures and 13.92% in maximum displacements.

Blast analysis of tunnels in Manhattan-Schist and Quartz-Schist using coupled-Eulerian–Lagrangian method

The tunnels are the lifeline of urban centers and play a significant role in the mass transportation of goods and services. They are the locales of accident and target for subversive activities, including terror attacks. Society needs to be well aware of such accidents and mitigation methods. We have carried out the analysis of internal blast loading using finite element analysis for two different rock tunnels constructed in Manhattan-Schist and Quartz-Schist rock employing Abaqus. The coupled-Eulerian–Lagrangian method has been considered for advanced modeling of the air inside the tunnel and 100 kg of Trinitrotoluene (TNT) explosive. TNT has been considered as material for better results by using Jones–Wilkins–Lee model and Eulerian volume fraction tool in the Abaqus have been used. This study concludes that rocks having a higher angle of friction are more resistant to blast loading. Further, rocks having lower cohesion are more blast resistant. However, if the design of tunnel support remains constant in rocks, then, damage in the tunnel lining remains the same, but deformations vary.

Characterization of encapsulated energetic materials for trace explosives aids for scent (TEAS)

ABSTRACT Encapsulation is proposed as a safer way of handling energetic materials. Different encapsulation methods for explosives, such as solvent evaporation, spray coating and supercritical carbon dioxide assisted encapsulation, were explored. Explosive training aids, where energetic materials, such as triacetone triperoxide (TATP), erythritol tetranitrate (ETN) and trinitrotoluene (TNT), are encapsulated in a polymer matrix were developed, followed by comprehensive quality control testing, including differential scanning calorimetry (DSC), thermogravimetric analysis-infrared spectroscopy (TGA-IR), gas chromatography-mass spectrometry (GC-MS), high-resolution mass spectrometry (HRMS) and sensitivity testing, and finally field approved by canine units trained on the pure explosive.

Application of [PVI-SO3H]NO3 as a novel polymeric nitrating agent with ionic tags in preparation of high-energetic materials.

In this paper, poly(vinyl imidazole) sulfonic acid nitrate [PVI-SO3H]NO3 was synthesized and fully characterized. Then, [PVI-SO3H]NO3 was applied for the preparation of energetic materials such as 1,1-diamino-2,2-dinitroethene (FOX-7), pentaerythritol tetranitrate (PETN), 1,3,5-trinitro-1,3,5-triazinane (RDX) and trinitrotoluene (TNT). The major advantages of the presented methodology are mild, facile workup, high yields and short reaction times. [PVI-SO3H]NO3 is a suitable nitrating agent for in situ generation of NO2 and without using any co-catalysts of the described nitrating reagent.

Modification of ANFO detonation parameters by biowaste addition

The present study relates to modification of ammonium nitrate fuel oil mixture. For many years, ammonium nitrate fuel oil has been one of the most popular explosives for use in mining operations. Therefore, it is manufactured and used widely in large volume. Although ammonium nitrate is a relatively strong oxidation agent, it is insufficient to detonate by itself. Therefore, it is generally admixed with liquid fuel such as diesel and various modifiers. Trinitrotoluene (TNT) and metal aluminium are typically used as additive. This paper studies ammonium nitrate fuel oil (ANFO) composition modified by biowaste dung as additive to generate efficient explosion and to result low cost blasting.The experiment results of modified ANFO with biowaste dung as additive illustrate that physical stability and absorption increased by 5% percent compared to regular ANFO. Also was revealed that average detonation brisance increased from 20.5 to 27.5 mm and detonation speed increased from 2300 to 3800 m/s compared to regular ANFO. This modified ANFO is lowered blasting cost from 50 to 150 tugriks per 1kg ANFO compared to aluminium and TNT additives.

Research on the Novel Honeycomb-Like Cabin Based on Computer Simulation

The antiknock capability and thermal protection performance of rescue capsules mainly depend on the structural design of the cabin. By designing a new type of cabin structure, it can resist the impact of explosion shock waves and thermal shocks. In this paper, a new honeycomb-like cabin is proposed; the model has a novel thermal insulation layer design. Then, the antiknock capabilities and thermal protection analysis are carried out by using computer software. The “Autodyn” analysis module in ANSYS Workbench 17.0 has been used to simulate the explosion of TNT with a certain quality in a single room. The pressure map over time and the pressure variation curve at different locations for a single room are obtained. Through the analysis module “Transient Structural,” the stress and deformation of the honeycomb-like cabin under the blast load are simulated. The “Transient Thermal” analysis module in the finite element software is used to conduct a transient thermal analysis on the cabin structure. The temperature map and the temperature rise curve of each layer of the cabin cases are obtained. The analysis results indicate that the honeycomb-like cabin design has a good antiknock capability and thermal protection performance, and it can meet the usage requirements of the rescue capsule under dangerous conditions.

Effect of Shock Wave on Constant Load Behaviour of Pb-Free/Cnt Solder Joint

The constant load behaviour of SAC305 solder joint with addition of carbon nanotube (CNT), exposed to shock wave condition was investigated. Formulated SAC305-CNT solder pastes with 0.04 wt. % CNT were manually printed to the printed circuit board (PCB) with copper surface finish to form solder joint. The solder joint was exposed to the shock wave condition via open field blast air test using Trinitrotoluene (TNT) explosive. Nanoindentation approach was used to determine the constant load behavior of the SAC305-CNT solder joint under shock wave condition. The results showed that addition of CNT reduced the indentation depth of SAC305 solder joint at 10 mN peak load for blast test sample and control sample. Indentation depth displacement of SAC305-CNT solder joint for blast test sample and control sample were reduced about ~ 42 and ~56%, respectively, if compared to the SAC305 solder joint for blast test sample and control sample. SAC305-CNT solder joint was experienced minimal changes of stress exponent when exposed to the shock wave. The existence of CNT in the solder joint slows down the depth displacement due to constant load.

Blast Test and Failure Mechanisms of Soft-Core Sandwich Panels for Storage Halls Applications.

In this paper, an experimental investigation is presented for sandwich panels with various core layer materials (polyisocyanurate foam, mineral wool, and expanded polystyrene) when subjected to a justified blast load. The field tests simulated the case for when 5 kg of trinitrotoluene (TNT) is localized outside a building’s facade with a 5150 mm stand-off distance. The size and distance of the blast load from the obstacle can be understood as the case of both accidental action and a real terroristic threat. The sandwich panels have a nominal thickness, with the core layer equal 100 mm and total exterior dimensions of 1180 mm × 3430 mm. Each sandwich panel was connected with two steel columns made of I140 PE section using three self-drilling fasteners per panel width, which is a standard number of fasteners suggested by the producers. The steel columns were attached to massive reinforced concrete blocks via wedge anchors. The conducted tests revealed that the weakest links of a single sandwich panel, subjected to a blast load, were both the fasteners and the strength of the core. Due to the shear failure of the fasteners, the integrity between the sandwich panel and the main structure is not provided. A comparison between the failure mechanisms for continuous (polyisocyanurate foam and expanded polystyrene) and non-continuous (mineral wool) core layer materials were conducted.

Study of photo induced charge transfer mechanism of PEDOT with nitro groups of RDX, HMX and TNT explosives using anti-stokes and stokes Raman lines ratios

The paper reports the charge transfer mechanism between poly (3,4-ethylenedioxythiophene) (PEDOT) and high energy materials such as RDX, HMX and TNT, respectively in terms of ratios of anti-stokes (AS) and stokes(S) Raman lines of NO2 bands. Generally it works as an effective sensing medium for the detection of explosives when mixed in an equal proportion and are subjected to 532 nm wavelength without any chemical treatment [1]. The pristine PEDOT is less sensitive to 532 nm wavelength (2.33 eV) but influences the Raman S and AS lines of explosives in the mixture. The study also reveals that a small quantity (one milligram) of PEDOT is sufficient to initiate the positive charge transfer mechanism between its oxidized state to the lone pairs of electrons on the oxygen atoms of the nitro group of the explosive molecules. Consequently, the intensity of the Raman spectra of RDX, HMX and TNT is dropped by an order of 22.5, 11.45 and 17.2 times, respectively along with the shift of the NO2 vibrational modes. It is also attributed to Photon-electron–phonon interaction. Finally, we have estimated the reduced mass of the functional group to ascertain the force constant and the intensity ratios of AS /S lines to confirm the charge transfer mechanism. The effect of charge transfer mechanism is also reflected in drastic change in transmission /absorption characteristics of FTIR spectra of same PEDOT and explosive mixtures.