High Explosives Research Articles

Enhancing the Reliability Assessment System for Crucial Powertrain Components through Design, Simulation, and Experiment

Article Enhancing the Reliability Assessment System for Crucial Powertrain Components through Design, Simulation, and Experiment Xiaochun Zeng 1,2,3, Gongcheng Wang 1,* , Ying Liu 2,3, Jing Liu 1,2,3, Yinglian Feng 2,3,4, Xiuyong Shi 5,6, Diming Lou 5,6, Lei Zhang 4, Tao Wei 1, and Zhong Li 1 1 Jiangling Motors Co. Ltd., Nanchang 330001, China 2 Jiangxi Province Women Science and Technology Workers Association, Nanchang 330036, China 3 Jiangxi Mechanical Engineering Society, Nanchang 330002, China 4 Magna PT Powertrain (Jiangxi), Nanchang 330200, China 5 Nanchang Automotive Institute of Intelligence & New Energy, Nanchang 330052, China 6 Tongji University, Shanghai 200092, China * Correspondence: gwang7@jmc.com.cn Received: 5 September 2023 Accepted: 19 September 2023 Published: 20 September 2023 Abstract: This article conducted innovative research on heat balance, cooling and structural strength by using Computer Aided Engineering (CAE), design, and experiment. These multifaceted approaches rely on the meticulous application of dynamic analysis, combustion analysis, fluid dynamics, and finite element analysis. This research has devised a fatigue-oxidation-creep multi-fatigue life prediction technique for thermal engines, coupled with an innovative water jacket optimization method. By addressing the design challenges arising from the demanding requirements of high explosion pressure, formidable power, and significant torque in power systems, this study has made significant strides in advancing the field. And this method was used to establish the development capability of powertrain electric drive components. To enhance reliability and prediction accuracy, a simulation and test calibration method was devised for Crucial Powertrain Components. This article establishes a robust foundation by providing comprehensive data support for reliability target decomposition, facilitating the efficient derivation of component reliability metrics. Additionally, it explores potential customer scenario failures and investigates the underlying mechanisms of powertrain malfunctions. By establishing a correlation matrix between failure modes, mechanisms, and reliability experiments, the coverage of powertrain failure mode verification experiments was significantly increased by over 95%. Ultimately, this article contributes to the formation of a comprehensive technical system for evaluating the reliability of crucial powertrain components, integrating design, simulation, and experiment.

Effect of shock-induced plastic deformation on mesoscale criticality of 1,3,5-trinitro-1,3,5-triazinane (RDX)

Shock-induced plasticity and structural changes in energetic molecular crystals are well documented. These processes couple with the leading shock wave and affect its propagation, resulting in long, transient responses that are challenging to capture with all-atom simulations due to their time scale. Hence, the effects of this coupling and the transient shock response on the formation of hotspots and the initiation of chemistry remain unclear. To address these challenges, we investigate the role of shock-induced plastic deformation on shock initiation with a recently developed particle-based, coarse-grain model for 1,3,5-trinitro-1,3,5-triazinane (RDX) that utilizes the generalized dissipative particle dynamics with reactions framework. This model enables reactive simulations at micron length scales, which are required to achieve steady-state shock propagation. The simulations show that the shock Hugoniot response of RDX can involve transient behavior for up to 150 ps before steady-state behavior is achieved for shock strengths above the elastic limit. Pore collapse simulations demonstrate that the intensity of the resulting hotspot will weaken as the shock transitions from transient to steady-state behavior, ultimately affecting the shock-to-deflagration transition. Our results highlight the importance of considering the mesoscopic effects of shock-induced plastic deformation in simulations of shock-to-deflagration transitions of high explosives.

From Concept to Synthesis: Developing Heat-Resistant High Explosives through Automated High-Throughput Virtual Screening

From Concept to Synthesis: Developing Heat-Resistant High Explosives through Automated High-Throughput Virtual Screening

Investigating residue dissolution of insensitive high explosives in two sandy soil types: A predictive modelling approach

The demand for munitions that are less likely to detonate accidentally has led to an increased use of Insensitive High Explosives (IHE), which contain substances like 2,4-dinitroanisole (DNAN) and 5-nitro-1,2,4-triazol-3-one (NTO). These substances have different properties compared to traditional explosives, and their potential environmental impact is not well understood. When these explosives are used in live-fire training exercises, their residues end up in the soil. It is important to determine how these residues dissolve and enter the soil. This study aimed to experimentally measure the rate at which an IHE formulation dissolves when exposed to rainwater with pH levels of 5.0 and 6.5, and to simulate how these residues dissolve and move through two different soil types. The dissolution rates were determined by conducting experiments in which IHE particles (30–60 mg) were exposed to water with varying pH levels and temperatures. The results showed that the dissolution rate of NTO did not vary with pH, while the dissolution rate of DNAN and RDX decreased with decreasing pH. Specifically, the dissolution rate of DNAN decreased from 18 ± 40 μg min−1 at pH 6.5 to 6 ± 4 μg min−1 at pH 5.0, while the dissolution rate of RDX decreased from 8 ± 4 to 3 ± 1 μg min−1. These findings were used to develop a stochastic model that successfully simulated the concentration of IHE in the leachate from soil columns over time. A sensitivity analysis revealed that while dissolution rates determined the amount of mass entering the soil, they did not significantly regulate the amount of mass that migrated through the soil and leached out of the soil columns.

Высокопредохранительные промышленные взрывчатые вещества

Высокопредохранительные промышленные взрывчатые вещества

Close-in explosion behaviors of scaled concrete–rubber layered circular meta-tunnels

Attenuating shock-induced vibration is crucial for the safety of underground protective structures, equipment, and personnel. Metamaterials and metastructures demonstrate great potential for sound and shock attenuation. However, to further enhance protection against blast shock waves, more rational metamaterials and metastructures need to be proposed and designed. Additionally, more experimental and theoretical studies are required to explore the vibration attenuation mechanisms and effects of these metastructures. To this end, this study proposes layered meta-structures consisting of stiff concrete layers and thin, soft rubber layers. Scaled meta-tunnel models were constructed, and close-in explosion experiments were carried out to investigate their vibration mitigation performance. The impacts of critical parameters, including layer materials, layer thickness, and scaled distance, on the vibration attenuation effects were investigated through comparing displacements, strains, acceleration data, and failure characteristics. The results reveal that under close-in field explosions with small TNT mass all these scaled models have greater displacement and more cracks, for laminated structure weakens the integral rigidity of the metastructure. Under great TNT mass, the difference gets much smaller. But all these structures have excellent vibration attenuation. The acceleration attenuation rate exceeds 98% for two-concrete-layered models with rubber layer thickness of 0.6 cm under explosion with TNT mass of 0.1 kg and stand-off distance of 1.0 m. When the TNT mass increases, the acceleration attenuation ability will be weakened. In this research, more layers will improve vibration attenuation only under high equivalent explosions as fracture of each layer will dissipate more energy. Overall, this study sheds light on the efficacy of meta-structures in attenuating vibration induced by explosive blasts and lays the groundwork for more sophisticated and advanced protective engineering designs.

Experimental testing of liner tray walls subjected to near field blast

AbstractExplosions produced in urban or industrial areas due to accidental or intentional detonation of high energy explosives (e.g., improvised explosive devices IED) are low‐probability but high‐impact events. If standoff distance from buildings or other constructions is small, explosions can cause structural failures and serious injuries or deaths of people. Preventing buildings from collapse is essential to minimizing casualties among occupants. However, experience has shown that even if the collapse is prevented, high number of injuries can result from fragments and flying debris generated by the non‐structural components or building envelopes. This risk could be minimized through appropriate design and selection of construction materials for most exposed elements (i.e., building envelopes). Although heavy/stiff systems were long considered appropriate to protect buildings against explosive threats, lighter and flexible systems are increasingly used for modern buildings. By allowing damage (but not fragmentation), the envelope system can provide predictable response, with minimal injuries in case of an explosion.The study presents the results of full‐scale blast tests on liner tray walls attached to a steel frame building. Walls are tested against increasing blast charges until complete failure. The ultimate strength is given by the failure of the end fasteners, after large bolt hole elongations coupled with the pull‐through of the end fasteners.

NANOMATERIALS AND QUANTUM DOTS FOR ELECTROCHEMICAL SENSING OF NITRO-AROMATICS-BASED EXPLOSIVES: A SHORT REVIEW

Explosives can be divided into low and high, the efficient detection of which is of utmost importance for security reasons. A major component of high explosives is the nitroaromatic compounds. These explosives, when sealed, have difficulty detecting. In this review work, the major techniques for explosive detection i.e. animal olfaction, calorimetric sensors, immunosensors, ion mobility spectrometry, and Raman spectroscopy are discussed. The materials or compounds comprising nitroaromatic sensors have been a topic of major research for the last three decades. Nanomaterials do provide an acceptable solution for portable, affordable, and efficient detection of analytes of explosive nature due to their redox properties. 3D nanomaterials like TiO2, Au, SiO2, Ag and CdSe-ZnS, 0D materials like CdSe, CdTe, ZnS and MoS2 can detect nitroaromatic compounds efficiently. In the upcoming technology, the incorporation of quantum dots is also considered for explosive detection. As an option for prospective research in the field, development in the use of boron nitride for detecting explosives is also a good option. A comprehensive review of such materials is discussed in this review paper.

Evaluation of a sequential anaerobic-aerobic membrane bioreactor system for treatment of traditional and insensitive munitions constituents

New energetic formulations containing insensitive high explosives (IHE), such as 2,4-dinitroanisole (DNAN), 3-nitro-1,2,4-triazole-5-one (NTO), and nitroguanidine (NQ) are being developed to provide safer munitions. The addition of IHE to munitions formulations results in complex wastewaters from explosives manufacturing, load and pour operations and demilitarization activities. New technologies are required to treat those wastewaters. The core objective of this research effort was to develop and optimize a dual anaerobic-aerobic membrane bioreactor (MBR) system for treatment of wastewater containing variable mixtures of traditional energetics, IHE, and anions. The combined system proved highly effective for treatment of traditional explosives (TNT, RDX, HMX), IHE (DNAN, NTO, NQ) and anions commonly used as military oxidants (ClO4−, NO3−). The anaerobic MBR, which was operated for more than 500 d, was observed to completely degrade mg L−1 concentrations of TNT, DNAN, ClO4− and NO3− under all operational conditions, including at the lowest hydraulic residence time (HRT) tested (2.2 d). The combined system generally resulted in complete treatment of mg L−1 concentrations of RDX and HMX to <20 μg L−1, with most of the degradation occurring in the anaerobic MBR and polishing in the aerobic system. No common daughter products of DNAN, TNT, RDX, or HMX were detected in the effluent. NTO was completely transformed in the anaerobic MBR, but residual 3-amino-1,2,4-triazole-5-one (ATO) was detected in system effluent. The ATO rapidly decomposed when bleach solution was added to the final effluent. NQ was initially recalcitrant in the system, but microbial populations eventually developed that could degrade >90% of the ∼10 mg L−1 NQ entering the anaerobic MBR, with the remainder degraded to <50 μg L−1 in the aerobic system. The dual MBR system proved to be capable of complete degradation of a wide mixture of munitions constituents and was resilient to changing influent composition.

Uncertainty quantification for high explosive reactant and product equations of state

Equations of state (EOSs) are typically represented as physics-informed models with tunable parameters that are adjusted to replicate calibration data as closely as possible. Uncertainty quantification (UQ) allows for the development of an ensemble of EOS parameters that are consistent with the calibration data instead of a single EOS. In this work, we perform UQ for the reactant and product EOSs for a variety of high explosives (HEs). In doing so, we demonstrate a strategy for dealing with heterogeneous (both experimental and calculated) data. We also use a statistical distance metric to quantify the differences between the various HEs using the UQ results.

Predicted viscosity of liquid HMX up to 40 GPa

AbstractViscous flow serves as a significant heating mechanism during the formation of hot spots, but the shear viscosity which determines this response is poorly characterized for most high explosives. Recently, a model was proposed for the shear viscosity of liquid HMX (1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocane) that was fit to pressures reaching 5 GPa, but this work uncovered uncertainties in the viscosity at 0 GPa and remains untested at higher pressures. We use molecular dynamics (MD) simulations and the Green‐Kubo formalism to predict the temperature‐ and pressure‐dependent shear viscosity of HMX over the pressure interval 0 GPa≤P≤40 GPa. Reassessment of the viscosity at 0 GPa rules out several potential explanations for discrepancies between earlier reports; we attribute these differences to details of MD trajectory integration impacting molecular flexibility. The shear viscosity of HMX exhibits an Arrhenius temperature dependence at each pressure considered, with exponential prefactor and activation energy terms that are also strong functions of pressure. An analytic form for the viscosity is developed based on an extension of the well‐known Andrade equation that simultaneously captures the temperature and pressure dependencies in the MD data up to 40 GPa. Comparison against a recently developed model for the viscosity of liquid RDX (1,3,5‐trinitro‐1,3,5‐triazinane) shows that both materials exhibit similar functional dependencies with the viscosity of HMX being higher by roughly an order of magnitude at a given temperature‐pressure state.

A novel oxidation-resistible Mg@Ni foam material for safe, efficient, and controllable hydrogen generation

As a promising in-situ hydrogen generation material, magnesium (Mg) has been seeking a promotion in its hydrogen generation property. Increasing the specific surface area, for example, replacing the Mg bulk using Mg powder, can greatly increase the hydrogen generation property, but it brings a high explosion risk, a difficulty in controlling the hydrogen generation, and an oxidation problem. In this work, we prepare a novel Mg@Ni foam material with Mg deposits on Ni foam by a physical vapor deposition method. The Ni foam not only increases the hydrolysis reaction areas of Mg by improving its specific surface area, but also kinetically accelerates the hydrolysis reaction rate of Mg by forming a uniform Mg-Ni galvanic cell. As a result, the Mg@Ni foam material realizes a near-theoretical hydrogen generation amount of Mg and a hydrogen generation rate significantly higher than those realized by the bulk Mg-based materials. The Mg@Ni foam material with the excellent hydrogen generation property is also free from explosion risk, easy to be controlled, and resistible to oxidation. A hydrogen fuel cell powered by the hydrogen generated by the Mg@Ni foam material can yield a steady voltage and run a small car for a long distance.

Acceleration characteristics of composite flame in the initial stage of gas/coal dust explosion and analysis of disaster intensification

To clarify the strengthening mechanism of gas/coal dust coupling explosion disasters, a 20 L spherical explosion test system, high-speed schlieren, and PIV analysis were used to study the acceleration characteristics and pressure change of composite flames in the initial stage of gas/coal dust explosion, and the flow field characteristics were also analyzed. The results showed that methane concentration had the most important influence on the formation and development of composite flame. When the methane concentration was 7.5% and 9%, the composite flame propagation showed obvious acceleration characteristics and developed spherically, the flame boundary was clear and smooth, with the whole flame being continuous and bright white. Meanwhile, the Markstein length of composite flame is positive, and increased with the increase of methane concentration and dust particle size but decreased with the increase of coal dust mass concentration, the Markstein length for 9% gas concentration was 7 times larger than 6% gas concentration, indicating the increase of gas concentration can obviously inhibit the instability of composite flame, which prolonged the residence time of coal dust particles in the composite flame, resulting in the enhancement of the pyrolysis of coal dust and improvement of explosion intensity. The PIV test results of 9% gas/coal dust explosion showed that due to the high initial explosion intensity, the negative pressure in the center of the composite flame made most of the coal dust particles undergo centripetal movement, and a large number of coal dust particles gathered around the front of the flame. At the same time, a large number of large vortices in opposite directions were formed around the front of the flame, which promoted rapid contact between the coal dust surface and oxygen and intensified the combustion reaction. The research results can provide guidance for the prevention and control of gas/coal dust composite explosion disasters.

Application of Six Equation Compressible Multifluid Model For the Numerical Simulation of Under-water Explosion

A two phase, six-equation compressible multifluid formulation, three-dimensional code is developed. In this paper, numerical simulation of underwater explosion near a free surface is presented as an application of the code developed. The flow structures and the processes are unsteady. Finite volume method is used for spatial discretization with HLLC scheme with second order accuracy for flux computation. Explicit, classical four stage Runge-Kutta method is used for temporal discretization. The main focus is to study the wave travel and capture the physics when a high-pressure high temperature gas explosion happens in water near to the free surface.

Linear shaped-charge jet optimization using machine learning methods

Linear shaped charges are used to focus energy into rapidly creating a deep linear incision. The general design of a shaped charge involves detonating a confined mass of high explosive (HE) with a metal-lined concave cavity on one side to produce a high velocity jet for the purpose of striking and penetrating a given material target. This jetting effect occurs due to the interaction of the detonation wave with the cavity geometry, which produces an unstable fluid phenomenon known as the Richtmyer–Meshkov instability and results in the rapid growth of a long narrow jet. We apply machine learning and optimization methods to hydrodynamics simulations of linear shaped charges to improve the simulated jet characteristics. The designs that we propose and investigate in this work generally involve modifying the behavior of the detonation waves prior to interaction with the liner material. These designs include the placement of multiple detonators and the use of metal inclusions within the HE. We are able to produce a linear shaped-charge design with a higher penetration depth than the baseline case that we consider and accomplish this using the same amount of or less HE.

Copper Azide-based Complexes without Repulsive Steric Clashes between Azides for Advanced Primary Explosives

Primary explosives are essential energy transfer materials in explosive systems. At present, heavy metal-containing materials, such as lead azide (LA), are still the most widely used primary explosives. Copper azide (CA)-based primary explosives are considered as promising replacements for LA. However, there has little advancement in the high initiation performance and high safety of CA-based primary explosives because of the absence of the relevant theories and structural models. Herein, we report [Cu(N3)(2-bmttz)]n1 with the exceptionally remarkable initiating capability and high safety. Performance tests indicated only 5 mg of 1 can successfully ignite the commercial secondary explosive RDX, as 1/6 priming charge of LA, demonstrating 1 is possibly the most efficient primary explosive known to date. Moreover, 1 possesses the rarely low impact sensitivity (IS = 2.5 J), which is comparable to that of LA and better than most of reported CA-based candidates. Both experimental and theoretical studies have shown that passivation of high-energy primary explosives can be achieved through the coordination between functional ligands and azide ions, in which azide ions without repulsive steric clashes only act as energetic building blocks. This work offers a new insight for designing high performance primary explosives for applications in advanced explosive systems.

New methods for trace analysis of gamma-irradiated pentaerythritol tetranitrate

High explosives (HEs) are used in a diverse range of applications in which they could be exposed to various radiation levels that may cause potential chemical changes. This study further evaluated pentaerythritol tetranitrate (PETN) that was previously aged with a low-level 2 kGy dose of gamma irradiation in order to understand chemical changes caused by irradiation. Both unirradiated PETN and gamma-irradiated PETN were analyzed using ultra high-pressure liquid chromatography coupled to quadrupole time of flight mass spectrometry (UHPLC-QTOF). The resulting data were processed in a non-targeted manner using Fisher's ratio analysis and multivariate curve resolution-alternating least squares (MCR-ALS) to aid in discovery and identification of the chemical changes brought about by irradiation without a priori knowledge. The application of using UHPLC-QTOF in combination with chemometric techniques for the analysis of irradiated samples has not previously been performed. Here we show how to use this method to provide chemical information that would otherwise not be discernible, such as the discovery of degradation of the various homologues of PETN. Major differences identified with radiolytic aging of the PETN sample included decomposition products that resulted from the degradation of the trigger linkage – the O–NO2 bonds – resulting in the formation of alcohol and aldehyde groups. Similar degradation was also observed in the PETN homologues as well as interconversion from one homologue to another.

Influence of barrel diameter on exploding foil initiators

AbstractExploding foil initiators (EFIs) offer several safety and timing advantages over other means of initiating high explosives. In order to increase the knowledge about the barrel diameter on sensitivity of HNS‐IV, several samples with different barrel diameter were investigated. Mean threshold voltage, and flyer velocity were measured and compared. Meanwhile, we present the flyer images with restricted condition of EFIs during flight by X‐ray phase contrast imaging system at the 45 TW laser facility at China Academy of Engineering Physics. The barrel diameter has a related to mean threshold voltage of EFIs. The lowest mean threshold voltage is 2830 V with 0.4 mm barrel diameter. The mean threshold voltage is increased by about 54 % as the barrel diameter decreases from 0.4 mm to 0.2 mm. But the decreased barrel diameter significantly increased the flyer velocity. The dynamic flyer image gives the evidence to prove that the impacting width of flyer is the key parameter of EFIs. The impacting width of flyer is related to barrel diameter. Meanwhile, the curvature of the flyer is related to barrel diameter and exploding foil width. This fundamental understanding has led to increased knowledge on the mechanism of EFIs and has allowed us to improve our predictive capability through modeling.

Crystal engineering of high explosives through lone pair-π interactions: Insights for improving thermal safety

In this high-risk/high-reward study, we prepared complexes of a high explosive anion (picrate) with potentially explosive s-tetrazine-based ligands with the sole purpose of advancing the understanding of one of the weakest supramolecular forces: the lone pair-π interaction. This is a proof-of-concept study showing how lone pair-π contacts can be effectively used in crystal engineering, even of high explosives, and how the supramolecular architecture of the resulting crystalline phases influences their experimental thermokinetic properties. Herein we present XRD structures of 4 novel detonating compounds, all showcasing lone pair-π interactions, their thermal characterization (DSC, TGA), including the correlation of experimental thermokinetic parameters with crystal packing, and in silico explosion properties. This last aspect is relevant for improving the safety of high-energy materials.

The Effect of high altitude nuclear explosions on the transmission characteristics of cavity filters

The high-altitude nuclear explosion instantly produces a large number of X-rays, which induce air plasma in the metal cavity filter, thus changing the frequency selection characteristics of the filter and affecting the performance of electronic devices. To research these situations, a three-dimensional time-varying plasma model is displayed in a cylindrical metallic cavity under X-rays irradiation, and the electromagnetic wave propagation characteristics at different air pressures and various times are calculated utilizing the shifted operator time domain finite difference (SO-FDTD) method. Furthermore, the change of the frequency selection characteristics for the cavity filter is also analyzed.