Philipp MoldtmannJulian BerkShannon RyanAndreas Klavzar...
1-12页
查看更多>>摘要：We evaluate an adaptive optimisation methodology,Bayesian optimisation(BO),for designing a mini-mum weight explosive reactive armour(ERA)for protection against a surrogate medium calibre kinetic energy(KE)long rod projectile and surrogate shaped charge(SC)warhead.We perform the optimisation using a conventional BO methodology and compare it with a conventional trial-and-error approach from a human expert.A third approach,utilising a novel human-machine teaming framework for BO is also evaluated.Data for the optimisation is generated using numerical simulations that are demonstrated to provide reasonable qualitative agreement with reference experiments.The human-machine teaming methodology is shown to identify the optimum ERA design in the fewest number of evaluations,out-performing both the stand-alone human and stand-alone BO methodologies.From a design space of almost 1800 configurations the human-machine teaming approach identifies the minimum weight ERA design in 10 samples.
查看更多>>摘要：The emergence of TKX-50,an energetic ionic salt with a high enthalpy of formation and low sensitivity,has opened a new path for the development of high-energetic,insensitive composite explosives.How-ever,due to the poor interfacial binding properties of TKX-50 with conventional binders,there is a lack of effective guidance for the design of TKX-50 based composite explosives.To address the above issues,the interactions between carboxymethyl cellulose acetate butyrate(CMCAB)and other binders with ex-plosives TKX-50/HMX were compared using the molecular dynamics method.Based on the simulations,TKX-50/HMX/CMCAB-based polymer-bonded explosives(PBXs)were prepared with CMCAB as binder,which displays a high binding energy(Ebind)with TKX-50 and high cohesive energy density(CED),and the effect of TKX-50 content on the performance of PBXs was investigated.The physical properties of PBXs,specifically the morphology,mechanical sensitivity,and thermal conductivity,were analyzed by SEM,sensitivity apparatus,and thermal conductivity meter,respectively.The specific heat capacity(Cp)and non-isothermal decomposition temperature of PBXs were tested by DSC,and then the corresponding thermal kinetic parameters were analyzed to evaluate their thermal safety.The adiabatic thermal decomposition processes of PBXs were tested using an ARC instrument.The decomposition mechanism and kinetics were also explored to further analyze their thermal stability and thermal safety under adiabatic conditions.The computer code EXPLO5 was used to predict the detonation parameters of PBXs.The results showed that CMCAB and TKX-50 displayed favorable interfacial bonding properties,and TKX-50 can be bonded with HMX to form a molding powder with a desirable morphology and safety profile.The TKX-50 in PBXs effectively improves the mechanical sensitivity and thermal safety of PBX and has a significant effect on the detonation performance of PBX.This research demonstrates a novel method suitable for screening and investigating high-energetic insensitive explosive systems compatible with TKX-50.
查看更多>>摘要：Ammonium dinitramide(ADN)is a new type of green energetic oxidizer with excellent energy density and low pollution combustion characteristics.However,the strong hygroscopicity has a significant impact on its practical application.To assist in the research on moisture-proof modification of ADN materials,an innovative hygroscopic modeling approach was proposed to evaluate the hygroscopicity of ADN at various temperatures and humidities.By investigating the diffusion coefficient of water mole-cules in molecular dynamics processes,a visual insight into the hygroscopic process of ADN was gained.Furthermore,analyzing the non-covalent interactions between ADN and water molecules,the hygro-scopicity of ADN could be evaluated qualitatively and quantitatively.The energy analysis revealed that electrostatic forces play a dominant role in the process of water adsorption by ADN,whereas van der Waals forces impede it.As a whole,the simulation results show that ADN presents the following hy-groscopic law:At temperatures ranging from 273 K to 373 K and relative humidity(RH)from 10％to 100％,the hygroscopicity of ADN generally shows an increasing trend with the rise in temperature and humidity based on the results of three simulations.According to the non-hygroscopic point(298 K,52％RH)of ADN obtained by experiment in the literature,a non-hygroscopic range of temperature and hu-midity for ADN can be depicted when the simulation results in relative hygroscopicity is less than or equal to 17％.This study can provide effective strategies for screening anti-hygroscopic modified mate-rials of ADN.
查看更多>>摘要：This paper explores the performances of a finite element simulation including four concrete models applied to a full-scale reinforced concrete beam subjected to blast loading.Field test data has been used to compare model results for each case.The numerical modelling has been,carried out using the suitable code LS-DYNA.This code integrates blast load routine(CONWEP)for the explosive description and four different material models for the concrete including:Karagozian & Case Concrete,Winfrith,Continuous Surface Cap Model and Riedel-Hiermaier-Thoma models,with concrete meshing based on 10,15,and 20 mm.Six full-scale beams were tested:four of them used for the initial calibration of the numerical model and two more tests at lower scaled distances.For calibration,field data obtained employing pressure and accelerometers transducers were compared with the results derived from the numerical simulation.Damage surfaces and the shape of rupture in the beams have been used as references for comparison.Influence of the meshing on accelerations has been put in evidence and for some models the shape and size of the damage in the beams produced maximum differences around 15％.In all cases,the variations between material and mesh models are shown and discussed.
查看更多>>摘要：To solve the problem of target damage assessment when fragments attack target under uncertain pro-jectile and target intersection in an air defense intercept,this paper proposes a method for calculating target damage probability leveraging spatio-temporal finite multilayer fragments distribution and the target damage assessment algorithm based on cloud model theory.Drawing on the spatial dispersion characteristics of fragments of projectile proximity explosion,we divide into a finite number of frag-ments distribution planes based on the time series in space,set up a fragment layer dispersion model grounded in the time series and intersection criterion for determining the effective penetration of each layer of fragments into the target.Building on the precondition that the multilayer fragments of the time series effectively assail the target,we also establish the damage criterion of the perforation and pene-tration damage and deduce the damage probability calculation model.Taking the damage probability of the fragment layer in the spatio-temporal sequence to the target as the input state variable,we introduce cloud model theory to research the target damage assessment method.Combining the equivalent simulation experiment,the scientific and rational nature of the proposed method were validated through quantitative calculations and comparative analysis.
查看更多>>摘要：Understanding the response of solid combustibles under high radiant fluxes is critical in predicting the thermal damage from extreme scenarios.Unlike the more moderate radiant fluxes in conventional hy-drocarbon fires,extreme events such as strong explosion,concentrated sunlight and directed energy can generate dynamic radiant fluxes at the MW/m2 level,creating a unique threat to materials.This study investigates the pyrolysis and spontaneous ignition behaviors of corrugated cardboard by using both experimental and numerical methods,under 10-cm dynamic high radiant fluxes ranging from 0.2 to 1.25 MW/m2 for 10 s.The spontaneous ignition process at dynamic high radiant fluxes was recorded and quantified.Two ignition modes were found at the critical radiant flux of 0.4 MW/m2,namely hot-gas spontaneous ignition and hot-residue piloted ignition.The latter is not the focus of this paper due to its extremely small probability of occurrence.The research reveals that the increase in flux intensity induces shorter delay times for both pyrolysis and ignition,lower ignition energy density,along with a corresponding rise in the critical mass flux and surface temperature at ignition moment.The simulation results are generally aligned with the experimental findings,despite some divergences may be attributed to model simplifications and parameter assumptions.The work contributes to a deeper insight into material behavior under extreme radiation,with valuable implications for fire safety and hazard assessment.
查看更多>>摘要：Long-term navigation ability based on consumer-level wearable inertial sensors plays an essential role towards various emerging fields,for instance,smart healthcare,emergency rescue,soldier positioning et al.The performance of existing long-term navigation algorithm is limited by the cumulative error of inertial sensors,disturbed local magnetic field,and complex motion modes of the pedestrian.This paper develops a robust data and physical model dual-driven based trajectory estimation(DPDD-TE)frame-work,which can be applied for long-term navigation tasks.A Bi-directional Long Short-Term Memory(Bi-LSTM)based quasi-static magnetic field(QSMF)detection algorithm is developed for extracting useful magnetic observation for heading calibration,and another Bi-LSTM is adopted for walking speed estimation by considering hybrid human motion information under a specific time period.In addition,a data and physical model dual-driven based multi-source fusion model is proposed to integrate basic INS mechanization and multi-level constraint and observations for maintaining accuracy under long-term navigation tasks,and enhanced by the magnetic and trajectory features assisted loop detection algo-rithm.Real-world experiments indicate that the proposed DPDD-TE outperforms than existing algo-rithms,and final estimated heading and positioning accuracy indexes reaches 5° and less than 2 m under the time period of 30 min,respectively.
查看更多>>摘要：In land warfare,trenches serve as vital defensive fortifications,offering protection to soldiers while engaging in combat.However,despite their protective function,soldiers often sustain injuries within these trenches.The lack of corresponding blast data alongside empirical injury reports presents a sig-nificant knowledge gap,particularly concerning the blast pressures propagating within trench spaces following nearby explosions.This absence hinders the correlation between blast parameters,trench geometry,and reported injury cases,limiting our understanding of blast-related risks within trenches.This paper addresses the critical aspect of blast propagation within trench systems,essential for evaluating potential blast injury risks to individuals within these structures.Through advanced computational fluid dynamics(CFD)simulations,the study comprehensively investigates blast injury risks resulting from explosions near military trenches.Employing a sophisticated computational model,the research analyzes the dynamic blast effects within trenches,considering both geometrical param-eters and blast characteristics influenced by explosive weight and scaled distance.The numerical simulations yield valuable insights into the impact of these parameters on blast injury risks,particularly focusing on eardrum rupture,lung injury,and traumatic brain injury levels within the trench.The findings elucidate distinct patterns of high-risk zones,highlighting unique characteristics of internal explosions due to confinement and venting dynamics along the trench.This study underscores the significance of detailed numerical modeling in assessing blast injury risks and provides a novel knowledge base for understanding risks associated with explosives detonating near military trenches.The insights gained contribute to enhancing safety measures in both military and civilian contexts exposed to blast events near trench structures.
查看更多>>摘要：This study employs a data-driven methodology that embeds the principle of dimensional invariance into an artificial neural network to automatically identify dominant dimensionless quantities in the pene-tration of rod projectiles into semi-infinite metal targets from experimental measurements.The derived mathematical expressions of dimensionless quantities are simplified by the examination of the exponent matrix and coupling relationships between feature variables.As a physics-based dimension reduction methodology,this way reduces high-dimensional parameter spaces to descriptions involving only a few physically interpretable dimensionless quantities in penetrating cases.Then the relative importance of various dimensionless feature variables on the penetration efficiencies for four impacting conditions is evaluated through feature selection engineering.The results indicate that the selected critical dimen-sionless feature variables by this synergistic method,without referring to the complex theoretical equations and aiding in the detailed knowledge of penetration mechanics,are in accordance with those reported in the reference.Lastly,the determined dimensionless quantities can be efficiently applied to conduct semi-empirical analysis for the specific penetrating case,and the reliability of regression functions is validated.
查看更多>>摘要：Reducing the vulnerability of a platform,i.e.,the risk of being affected by hostile objects,is of paramount importance in the design process of vehicles,especially aircraft.A simple and effective way to decrease vulnerability is to introduce protective structures to intercept and possibly stop threats.However,this type of solution can lead to a significant increase in weight,affecting the performance of the aircraft.For this reason,it is crucial to study possible solutions that allow reducing the vulnerability of the aircraft while containing the increase in structural weight.One possible strategy is to optimize the topology of protective solutions to find the optimal balance between vulnerability and the weight of the added structures.Among the many optimization techniques available in the literature for this purpose,multi-objective genetic algorithms stand out as promising tools.In this context,this work proposes the use of a in-house software for vulnerability calculation to guide the process of topology optimization through multi-objective genetic algorithms,aiming to simultaneously minimize the weight of protective struc-tures and vulnerability.In addition to the use of the in-house software,which itself represents a novelty in the field of topology optimization of structures,the method incorporates a custom mutation function within the genetic algorithm,specifically developed using a graph-based approach to ensure the con-tinuity of the generated structures.The tool developed for this work is capable of generating protections with optimized layouts considering two different types of impacting objects,namely bullets and frag-ments from detonating objects.The software outputs a set of non-dominated solutions describing different topologies that the user can choose from.
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