Explosion Damage Research Articles

Effect of annealing on the damage threshold and optical properties of HfO2/Ta2O5/SiO2 high-reflection film

The effect of thermal annealing on the optical properties, microstructure, and laser-induced damage threshold (LIDT) of HfO2/Ta2O5/SiO2 HR films has been investigated. The transmission spectra shift to a short wavelength and the X-ray diffraction peaks of monoclinic structure HfO2 are enhanced after thermal annealing. The calculated results of the m(−111) diffraction peak show that the HfO2 grain size is increased, which is conducive to increasing the thermal conductivity. Thermal annealing also reduces the laser absorption of high-reflection films. The improvement of thermal conductivity and the decrease of laser absorption both contribute to the improvement of LIDT. The experimental results show that the highest LIDT of 22.4 J/cm2 is obtained at 300°C annealing temperature. With the further increase of annealing temperature, the damage changes from thermal stress damage to thermal explosion damage, resulting in the decrease of LIDT.

Structural damage analysis of explosive testing experimental bay using HEXDAM Modelling software

Modelling of structural damages is a tool for making blast damage assessments resulting from an explosion on a localized area. This can be used as a damage/ injury assessment tool to determine the amount of blast damage/injury done to individual structures/ persons in a certain geographical area due to the detonation of explosives at ground level or at a specified height above the ground. This paper deals with prediction the structural damages of an experimental bay building when subjected to explosive testing, using HEXDAM (High Explosive Damage Assessment Modelling) software. The modelling software helps to predict the blast parameters at various points and the structural damages caused to the structures with in a facility. The basic outputs of HEXDAM are designed to provide data such as before/after blast display; damage/injury table; damage vs distance; pressure contours; damage/injury contours and the data tables for overpressure, dynamic pressure and damage/injury at each grid point. The experimental bay building along with the facility building was scientifically modelled with the trial set up using this software. The structural damages to the experimental bay and the nearby facilities are analysed when the building set up is subjected to the explosive loading at the height of 1m. The over pressure data at various points from the ground level to the height of 9m have been generated in this modelling. The Outputs are in the form of Damage vs injury tables, before and after blast displays, pressure and damage vs injury contour plots and Damage, injury-versus-distance graphs.

A Predictive Model for Damage Assessment and Deformation in Blast Walls Resulted by Hydrocarbon Explosions

In this paper, a new method is developed to find the ductility ratio in blast walls, resulted by hydrocarbon explosions. In this method, only the explosion energy and distance from the centre of explosion are required to find the damage by using simple predictive models in terms of empirical‐type formulas. The explosion model herein is a TNO multiphysic method. This provides the maximum overpressure and pulse duration in terms of the explosion length and distance from explosion centre. Thereafter, the obtained results are combined with the SDOF model of the blast wall to determine the ductility ratio and the damage. By using advanced optimisation techniques, two types of predictive models are found. In the first model, the formula is found in terms of 2 parameters of explosion length and distance from explosion centre. However, the 2nd model has 3 parameters of explosion length, distance, and also the natural period of the blast wall. These predictive models are then used to find explosion damages and ductility ratio. The results are compared with FEM analysis and pressure‐impulse (P‐I) method. It is shown that both types of models fit well with the outputs of the simulation. Moreover, results of both models are close to FEM analysis. The comparison tables provided in this paper show that, in the asymptotic region of P‐I diagrams, results are not accurate. Therefore, this new method is superior to classical pressure‐impulse (P‐I) diagrams in the literature. Advantage of the new method is the easy damage assessment by using simple empirical‐type formulas. Therefore, the researchers can use the method in this paper, for damage assessment in other types of blast resistive structures.

A MILP approach for optimal storage vessels layout based on the quantitative risk analysis methodology

Abstract The layout design for storage vessels is an important issue to keep safe process plants, since the accidents originated in storage areas are almost one-third of all reported accidents. In order to reduce fire and explosion damages different mathematical approaches have been proposed; however, most of them are not suitable for real storage facilities design. In this work, a MILP approach has been developed to find the optimal layout of storage vessels, seeking to minimize the cost associated with potential damage of fire and explosion. This approach allows allocation of suitable sites for storage vessels, reducing accidents propagation, and domino effect while keeping safety as much as possible the plant assets. In this way, the optimization approach provides substantial support for decision-makers during the design stage. The study case used to test the mathematical model considers 19 vessels, six buildings, five process facilities and 25 possible scenarios, which includes 16 fires and 9 explosions.

Numerical simulations of microcrack-related damage and ignition behavior of mild-impacted polymer bonded explosives

A physical model is developed to describe the viscoelastic-plastic deformation, cracking damage, and ignition behavior of polymer-bonded explosives (PBXs) under mild impact. This model improves on the viscoelastic-statistical crack mechanical model (Visco-SCRAM) in several respects. (i) The proposed model introduces rate-dependent plasticity into the framework which is more suitable for explosives with relatively high binder content. (ii) Damage evolution is calculated by the generalized Griffith instability criterion with the dominant (most unstable) crack size rather than the averaged crack size over all crack orientations. (iii) The fast burning of cracks following ignition and the effects of gaseous products on crack opening are considered. The predicted uniaxial and triaxial stress-strain responses of PBX9501 sample under dynamic compression loading are presented to illustrate the main features of the materials. For an uncovered cylindrical PBX charge impacted by a flat-nosed rod, the simulated results show that a triangular-shaped dead zone is formed beneath the front of the rod. The cracks in the dead zone are stable due to friction-locked stress state, whereas the cracks near the front edges of dead zone become unstable and turn into hotspots due to high-shear effects.

Electrically-triggered micro-explosion in a graphene/SiO2/Si structure

Electrically-triggered micro-explosions in a metal-insulator-semiconductor (MIS) structure can fragment/atomize analytes placed on it, offering an interesting application potential for chip-scale implementation of atomic emission spectroscopy (AES). We have investigated the mechanisms of micro-explosions occurring in a graphene/SiO2/Si (GOS) structure under a high-field pulsed voltage drive. Micro-explosions are found to occur more readily in inversion bias than in accumulation bias. Explosion damages in inversion-biased GOS differ significantly between n-Si and p-Si substrate cases: a highly localized, circular, protruding cone-shape melt of Si for the n-Si GOS case, whereas shallow, irregular, laterally-propagating trenches in SiO2/Si for the p-Si GOS case. These differing damage morphologies are explained by different carrier-multiplication processes: in the n-Si case, impact ionization propagates from SiO2 to Si, causing highly-localized melt explosions of Si in the depletion region, whereas in the p-Si case, from SiO2 towards graphene electrode, resulting in laterally wide-spread micro-explosions. These findings are expected to help optimize the GOS-based atomizer structure for low voltage, small-volume analyte, high sensitivity chip-scale emission spectroscopy.

Building pathology 101, explosion damage

Building pathology 101, explosion damage

Safe performance analysis of flammable mixture working fluid leakage in Organic Rankine Cycle

As working fluid in Organic Rankine Cycle (ORC) used for engine waste heat recovery, the unavoidable leakage of HCs/CO2 mixture in practical application is a threat for safety due to its flammability. In this work, safe performance comparison of propylene/carbon dioxide and pentane/carbon dioxide is carried out through concentration distribution analysis and explosion damage degree evaluation. In addition, influence factors of dispersion characteristic were analysed. According to the assessment results, the concentration of propylene is higher than pentane at the same position after leakage. However, the damage degree to buildings and individuals caused by explosion increase from propylene/carbon dioxide to pentane/carbon dioxide. Wind speed and hydrocarbon ratio have obvious effect on the dispersion characteristics. To improve the safe performance of hydrocarbon/carbon dioxide mixture in practical application, gas detectors in the middle of the ceiling can detect the occurrence of gas leakage in less than one second. The maximum ratio of propylene and pentane should be 0.4 when blending with carbon dioxide in view of explosion risk.

Explosive blast damage resistance of three-dimensional textile composites

The damage resistance of 3D textile composites when subjected to shock wave loading caused by an explosive blast is experimentally investigated. Non-crimp 3D orthogonal textile carbon-epoxy composites with different volume contents of through-thickness z-binder yarns are subjected to explosive blasts of increasing intensity, and the resultant damage is compared to a 2D woven carbon-epoxy laminate. At high blast impulse, the 3D textile composites are highly effective at resisting large delamination crack growth, and display superior damage resistance compared to the 2D laminate. The delamination resistance of the 3D textile composites at high blast impulse increases with their z-binder yarn content, and this correlates with higher modes I and II interlaminar fracture toughness properties. Furthermore, the 2D laminate completely shatters under high blast impulse whereas the 3D textile composites remain intact, which is also evidence of higher explosive damage resistance.

비선형 폭발해석에 의한 콘크리트 구조물의 손상도 평가

일반적으로 구조물에 폭발, 충돌, 지진과 바람 등과 같이 짧은 시간에 큰 하중이 작용하게 되면 구조물은 국부적으로 재료의 대변형(large deformation), 대회전(large rotation), 대변형률(large strain)등이 발생하게 된다. 이와 같은 현상을 해석하려면 전산연속체 역학에 기초하여 유체-구조물 상호작용 등을 고려할 수 있는 하이드로코드(Hydrocode)의 도움이 필요하다. 또한, 폭발로 인해 발생되는 순간 동역학적인 폭발 메커니즘은 매우 복잡하기 때문에 폭발실험을 병행하여 거동을 예측하는 것이 합리적인 방법이지만 막대한 비용과 시설이 요구되므로 한계가 있는 것도 사실이다. 따라서 본 논문에서는 하이드로코드인 AUTODYN을 사용하여 폭발해석한 결과를 기수행된 철근콘크리트 슬래브의 폭발실험 결과와 비교하여 폭발해석 방법의 타당성을 검토하였고, 동일한 폭발해석 모형에 대하여 철근 배근간격, 피복두께의 변화 및 수직철근 유무에 따른 폭발 손상도를 비교검토하였다. 검토한 결과, 철근의 배근간격에 대한 철근콘크리트 슬래브 두께의 비가 커질수록, 지름이 큰 철근보다 지름이 작은 철근을 많이 사용할수록, 마지막으로 수직철근을 배근할수록 콘크리트 구조물의 내폭성능이 향상됨을 알 수 있었다. In general, the large loads which are applied from explosion, impact, earthquake and wind at a short time caused the materials of structures to large deformations, rotations and strains locally. If such phenomena will be analyzed, hydrocodes which can be considered fluid-structure interaction under computational continuum mechanics are inevitably needed. Also, the explosion mechanism is so complicated, it is reasonable that the behaviors of structure are predicted through explosion analyses and experiment at the same time. But, unfortunately, it is true that explosion experiments are limited to huge cost, large experiment facilities and safety problems. Therefore, in this study, it is shown that the results of explosion analyses using the AUTODYN are agreed with those of existing explosion experiments for reinforced concrete slabs within reasonable error limits. And the explosion damage of the same reinforced concrete slab are assessed for quite different reinforcement arrangement spacings, concrete cover depths, and vertical reinforcements. From the explosion analyses, it is known that the more the ratio of slab thickness to reinforcement arrangement spacing is increased, and small-diameter reinforcements are used than large-diameter reinforcements on the same reinforcement ratio, and vertical reinforcements are used, the more the anti-knock capacities are improved.

호흡용 고압용기 파열 피해영향 분석에 따른 안전충전함 개발

소방서, 스쿠버 등 공기호흡기 용기 충전시설의 고압가스안전관리법에 따른 허가 또는 신고를 하지 않고 운영하고 있으며, 시설개선 및 공기호흡기 충전중 사고발생에 따른 안전관리가 필요하다. 정부에서는 불법운영 해소를 위해 노력하고 있으며, 고압으로 인한 위험으로부터 안전거리와 방호벽 설치와 동등이상의 안전성을 확보하기 위한 방법으로 안전충전함을 설치하여 운용하는 방법을 대안으로 제시하였다. 방호벽 설치기준을 갈음할 수 있는 안전충전함은 용기파열 시 순간 과압이 원만하게 분산될 수 있는 내부구조를 가져야 하며, 파편이 분산하는 것을 최소화 하고 모든 파편의 외부 비산을 방지하고, 외부로 방출되는 과압이 작업자가 위치하지 않은 곳(상부 및 하부)으로 분출되도록 하여 방호벽의 성능을 갖추도록 하여야 한다. 본 연구에서는 압축공기의 물리적 폭발에 따른 피해 영향을 계산하고, 실제 충전함 시제품을 제작하여 시험용 용기를 가스로 파열시키는 파열시험으로 안전충전함의 외함변화를 관찰 한 결과, 공기 배출구조설계 등을 통하여 안전충전함 내부의 과압을 해소할 수 있음을 확인 하였다. A fire station and scuba have operated filling facilities for respiratory high-pressure cylinder without getting authority or reporting according to High-Pressure Gas Safety Control Act. They need facility improvement and special management to make provision for the time of accident during filling process. The Government have strived to correct illegal operations and suggested an alternative, establishing and operating the safety cabinet. It insures a safety being distance from danger caused by overpressure and a safety provoked by the protective wall equals or superiors. The safety cabinet is required to have an internal structure that smoothly distribute overpressure at the time of rupture. Plus, it needs to minimize fragments. It is also equipped with the performance of protective wall that makes overpressure to outside vent on the place where there is no person (top or bottom). This study calculated the consequence of physical explosion damage and built a prototype of safety cabinet. In addition, through the gas burst test, it derives for the ways to mitigate the physical explosion damage.

Lightweight Concrete with Different Content of PP Fibers Exposed to High Temperature

Mechanical resistance of building materials exposed to high temperatures, e.g. fire loading or explosion damage, is one of parameters that determine the safety of structures. The residual strengths determine load-bearing capacity of construction after exposure of extreme temperatures. Mechanical properties of materials exposed to high temperature (400°C and more) are primarily tested and determined at ambient temperature testing mode. It means, that the sample is exposed to high temperature loading and after cooling to the nature temperature T0 = 20°C are tested in common used testing machines. These residual strengths are a valuable foundation for an assessment of the structure exposed to a temperature load. The paper presents the test results of mechanical properties at hot state compared to the test results at ambient temperature for four type of lightweight concretes exposed to several temperature levels Tmax = 200°C, 400°C, 600°C, 800°C and Tmax = 1 000°C.

Numerical investigation of surface conduit parallel gas pipeline explosive based on the TNT equivalent weight method

With the rapid development of petroleum industry, the transport pipelines of oil and gas are increasingly constructed to minimize land use conflicts. Therefore, the parallel pipelines are unavoidable in order to save land resource, reduce the pipeline construction and maintenance costs. The economy and security of pipeline laying and running is the primary problem considered in pipeline construction, which the parallel spacing plays a decisive role to. The leakage of natural gas is very serious and dangerous due to its flammable and combustible. The explosive of leak gas causes impact failure to parallel pipeline. Specific to the surface conduit parallel gas pipeline, numerical simulation of leak natural gas explosive was carried out based on TNT equivalent weight method. Explosive damage degree of pipeline decreased with the pipeline distance increasing. Consulting with the pipeline ovalization strain design criteria and the combustion effect, the safety parallel natural gas pipeline space maybe at least 4 m to ensure the surface conduit parallel pipeline safely and steadily operation.

Explosion induced dynamic responses of blast wall on FPSO topside: Blast loading application methods

Topside areas on an offshore oil and gas platform are highly susceptible to explosion. A blast wall on these areas plays an important role in preventing explosion damage and must withstand the expected explosion loads. The uniformly distributed loading condition, predicted by Explosion Risk Analyses (ERAs), has been applied in most of the previous analysis methods. However, analysis methods related to load conditions are inaccurate because the blast overpressure around the wall tends to be of low-level in the open area and high-level in the enclosed area. The main objectives of this paper are to study the effects of applying different load applications and compare the dynamic responses of the blast wall. To do so, various kinds of blast pressures were measured by Computational Fluid Dynamics (CFD) simulations on the target area. Nonlinear finite element analyses of the blast wall under two types of identified dynamic loadings were also conducted.

플라스틱 부유 분진의 폭발특성과 화염전파속도

산업분야에서 사용되는 플라스틱 분진은 대부분 가연성이며 화재폭발사고 위험성이 있다. 그러나 산업현장에서 안전한 취급을 위해 활용할 수 있는 폭발특성 자료는 매우 적다. 본 연구에서는 사업장에서 취급하는 다양한 플라스틱 분진 의 폭발특성을 실험적으로 조사하여 관련 자료와 안전정보를 제공하는 것을 목적으로 수행하였다. 이를 위해 20 L 분진폭발시험장치를 사용하여 각종 폭발특성값을 측정하였다. 그 결과 ABS (<TEX>$209.8{\mu}m$</TEX>), PE (<TEX>$81.8{\mu}m$</TEX>), PBT (<TEX>$21.3{\mu}m$</TEX>), MBS (<TEX>$26.7{\mu}m$</TEX>) 및 PMMA (<TEX>$14.3{\mu}m$</TEX>)시료의 분진폭발지수(<TEX>$K_{st}$</TEX>)는 각각 62.4, 59.4, 70.3, 303, 203.6[<TEX>$bar{\cdot}m/s$</TEX>]의 값이 얻어졌다. 또한 플라스틱 분진폭발에 의한 피해예측을 위하여 분진폭발압력에서 분진의 연소속도가 일정하다고 가정하고 최대압력소요시간 및 화염도달시간을 고려한 화염전파속도모델을 통하여 분진폭발시의 화염전파속도를 추정하였다. Many of plastic powders handled in industry are combustible and have the hazard of dust fire and explosion accidents. However poor information about the safe handling has been presented in the production works. The aim of this research is investigated experimentally on explosive characteristics of various plastic powders used in industry and to provide additional data with safety informations. The explosibility parameters investigated using standard dust explosibility test equipment of Siwek 20-L explosion chamber. As the results, the dust explosion index (<TEX>$K_{st}$</TEX>) of ABS (<TEX>$209.8{\mu}m$</TEX>), PE (<TEX>$81.8{\mu}m$</TEX>), PBT (<TEX>$21.3{\mu}m$</TEX>), MBS (<TEX>$26.7{\mu}m$</TEX>) and PMMA (<TEX>$14.3{\mu}m$</TEX>) are 62.4, 59.4, 70.3, 303 and 203.6[<TEX>$bar{\cdot}m/s$</TEX>], respectively. And flame propagation velocity during plastic dust explosions for prediction of explosive damage was estimated using a flame propagation model based on the time to peak pressure and flame arrival time in dust explosion pressure assuming the constant burning velocity.

Effect of filling ratio on premixed methane/air explosion in an open-end pipe

The propagation characteristics of premixed methane/air explosion under different filling ratios (20%, 30%, 40%, 50%, 60%, and 100%) were studied using an experimental system. The results indicate that the peak overpressure showed a decreasing trend at the initial stage but then showed an increasing trend until reaching its maximum value under different filling ratios. As the explosion propagated to the open end, the overpressure showed a downtrend. At this point, the flame speed initially increased along the pipe but then dropped dramatically. In addition, the explosion overpressure and flame speed increased with the increase of filling ratio. However, when the filling ratio reached 50%, the explosion overpressure and flame speed tended to be stable and the increase was not obvious. These results will be of great importance in evaluating the explosive damage to equipment and human personnel working in coal mines or other chemical industries.

Kaohsiung Vapour Explosion - A Detailed Analysis of the Tragedy in the Harbour City

On the midnight of July 31st, 2014, a catastrophic vapor explosion occurred in the downtown of Kaohsiung city. The incident was initiated from a leak of an underground pipeline transporting pressurized propylene liquid. Analysis of pipeline operation logs and pipeline break release modeling suggested that at least 90,000 kg of propylene leaked, entered the underground trench and spread into the trench 4.5 km in distance before meeting an ignition source some three hours later after the leak. The ignition caused a significant vapor explosion which blew out the road above the underground trench, damaged more than one hundred vehicles on the road with thirty two fatalities and more than three hundred injuries. This article takes an in-depth look at the explosion incident covering the events leading to the explosion, explosion damage, cause of the leak, spread of the leak, and identification of a probable ignition source. Lessons learnt and recommendations are given to prevent and mitigate the occurrence of similar incidents.

Improved Explosion Consequence Analysis with Combined CFD and Damage Models

The most-widely used approach to explosion consequence analysis is the classical engineering method based on the combination of TNT equivalence, scaled distances and overpressure-based damage levels. This approach rests on established and easily comprehensible elements and permits a fast assessment of explosion consequences. There are however several limitations inherent in this approach. In contrast, a simulation-based approach using computational fluid dynamics (CFD) and structural dynamics (CSD) methods permits an analysis with a high level of detail regarding both the prediction of the explosive loads and the caused damage. This comes at the cost of complex simulation models which require expert knowledge, intense validation and a high computational effort. To bridge the gap between the classical simplified approach and the CFD/CSD based methods, we have developed a specialized CFD tool, the APOLLO Blastsimulator, with a built-in library of experimentally validated damage models and blast-injury models suitable for an improved explosion consequence analysis. The high resolution CFD tool uses globally and locally adaptive Cartesian grids and includes models for TNT detonations as well as gas detonations. The built-in damage models are based on experimentally validated single-degree-of-freedom (SDOF) representations of structural components. This paper gives a brief review on the classical approaches and their limitations and an overview on the concepts used in the APOLLO Blastsimulator and the SDOF damage models. For an exemplary explosion scenario the results obtained with different explosive source and damage models are compared.

Confined vapor explosion in Kaohsiung City – A detailed analysis of the tragedy in the harbor city

On the midnight of July 31st, 2014, a catastrophic vapor explosion occurred in the downtown of Kaohsiung city. The incident was initiated from a leak of an underground pipeline transporting pressurized propylene liquid. Analysis of pipeline operation logs and pipeline break release modeling suggested that at least 90,000 kg of propylene leaked, entered the underground trench and spread into the trench 4.5 km in distance before meeting an ignition source some three hours later after the leak. The ignition caused a significant confined vapor explosion which blew out the road above the underground trench, damaged more than one hundred vehicles on the road with thirty two fatalities and more than three hundred injuries. This article will first describe the background of the pipeline installation follows by an in-depth look at the explosion incident covering the events leading to the explosion, explosion damage, cause of the leak, spread of the leak, identification of a probable ignition source, and root causes in safety culture. Finally, lessons learnt and recommendations are given to prevent and mitigate the occurrence of similar incidents.

Study of the destruction of ventilation systems in coal mines due to gas explosions

Gas explosions presented a serious safety threat in the mining industry worldwide. Many coal miners had been killed due to explosions in mining. The malfunction of a ventilation system caused by a gas explosion was the primary reason for casualties in coal mines. In this study, two models were built to simulate ventilation systems in which gas explosions often occur. The models consisted of a pipe incorporating weak panels. Using each model, the propagation of the overpressure shock wave and the distribution on the ventilation system were verified. According to the characteristics of multiple ventilation facilities in a local ventilation system, the combined effects of bends and bifurcations and the destruction of ventilation facilities in the local network model due to an overpressure wave were analyzed. By analyzing the distribution of the methane/air mixture explosion overpressure wave in the pipe models, the effect of a weak panel on the explosion shock wave and the degree of explosion damage were characterized by the statistical results from the sizes of the fragments. The explosion wave peak overpressure in the forward direction was higher than the peak overpressure in the elbow bend direction. After explosion, the production gas was immediately extracted and the composition was analyzed. The destruction order for different ventilation facilities in the local ventilation system was determined according to the pipe model experimental results. The disaster of gas explosion for ventilation network and workers was analyzed, and the spare door was designed to recover the ventilation system after gas explosion.