Pulse load on a stationary barrier during an explosion in water

С использованием экспериментальных данных о взрывах в воде найдена аналитическая зависимость распределения удельного импульса взрывной нагрузки по длине балки. Учтены эффекты отражения возмущенного потока воды от поверхности преграды, глубина ее расположения в водоёме, взаимное расположение сферического заряда ВВ и преграды в воде, физические характеристики заряда. Using experimental data on explosions in water, an analytical dependence of the distribution of the specific impulse of the explosive load along the length of the beam is found. The effects of reflection of the disturbed water flow from the barrier surface, the depth of its location in the reservoir, the mutual location of the spherical explosive charge and the barrier in the water, the physical characteristics of the charge are taken into account.

Research on the Dynamic Response of Frame Structure under the Explosion Load of Acetylene-Air Mixture

Explosion is the act of generating huge energy in an instant and spreading rapidly around it. Due to the suddenness, fast propagation speed and high peak load of explosions, compared with other natural disasters, the damage it brings to humans is more significant and difficult to prevent. Among them, the explosion of acetylene-air mixture is the most typical explosion problem. This paper uses SAP2000 finite element software to perform a fine simulation of actual explosion events, studies the effect of the explosion of acetylene-air mixture on the frame structure column, and discusses the displacement and acceleration changes of various components. Research shows that the use of the principle of linear assumption of explosive load can effectively simulate the actual explosion situation. The structural damage and deformation caused by the explosive load have locality and weak transmission. When the peak of the explosion load is larger, the structure deformation is greater, and the impact of the explosion load on the structure is isotropic.

Deformation of elastic-viscous beams by explosive load in water

Представлено аналитическое решение задачи о деформировании взрывом сосредоточенного заряда конденсированного взрывчатого вещества (ВВ) балки, материал которой чувствителен к скорости деформации. Влияние внешней среды (воды) на процесс и результаты деформирования учитывается введением присоединенной массы. Коэффициент вязкости и модуль упругости в фиксированных интервалах скоростей деформирования определяются из экспериментов. Для этих параметров, характеризующих материал балки при импульсном деформировании, получена аналитическая взаимосвязь и нижняя граница значений для коэффициента вязкости. Решение задачи найдено методом разделения переменных в определяющем уравнении движения. При этом форма упругой линии балки для каждого момента времени выбрана, исходя из требования выполнения граничных условий и принципа минимума работы деформирования. An analytical solution to the problem of deformation by an explosion of a concentrated charge of a condensed explosive (HE) of a beam, the material of which is sensitive to the rate of deformation, is presented. The influence of the external environment (water) on the process and the results of deformation is taken into account by introducing the added mass.The viscosity coefficient and the modulus of elasticity in fixed intervals of strain rates are determined from experiments. For these parameters, which characterize the material of the beam under impulse deformation, an analytical relationship and a lower limit of values for the viscosity coefficient are obtained. The solution to the problem is found by the method of separation of variables in the governing equation of motion. In this case, the shape of the elastic line of the beam for each moment of time is selected based on the requirement to fulfill the boundary conditions and the principle of minimum deformation work.

Computational predictions for predicting the performance of steel 1 panel shear wall under explosive loads

Purpose The resistance of steel plate shear walls (SPSW) under explosive loads is evaluated using nonlinear FE analysis and surrogate methods. This study uses the conventional weapons effect program (CONWEP) model for the explosive load and the Johnson-Cook model for the steel plate. Based on the Taguchi method, 25 samples out of 100 samples are selected for a parametric study where we predict the damaged zones and the maximum deflection of SPSWs under explosive loads. Then, this study uses a multiple linear regression (MLR), multiple Ln equation regression (MLnER), gene expression programming (GEP), adaptive network-based fuzzy inference (ANFIS) and an ensemble model to predict the maximum detection of SPSWs. Several statistical parameters and error terms are used to evaluate the accuracy of the different surrogate models. The results show that the cross-section in the y-direction and the plate thickness have the most significant effects on the maximum deflection of SPSWs. The results also show that the maximum deflection is related to the scaled distance, i.e. for a value of 0.383. The ensemble model performs better than all other models for predicting the maximum deflection of SPSWs under explosive loads. Design/methodology/approach The SPSW under explosive loads is evaluated using nonlinear FE analysis and surrogate methods. This study uses the CONWEP model for the explosive load and the Johnson-Cook model for the steel plate. Based on the Taguchi method, 25 samples out of 100 samples are selected for a parametric study where we predict the damaged zones and the maximum deflection of SPSWs under explosive loads. Then, this study uses a MLR, MLnER, GEP, ANFIS and an ensemble model to predict the maximum detection of SPSWs. Several statistical parameters and error terms are used to evaluate the accuracy of the different surrogate models. The results show that the cross-section in the y-direction and the plate thickness have the most significant effects on the maximum deflection of SPSWs. The results also show that the maximum deflection is related to the scaled distance, i.e. for a value of 0.383. The ensemble model performs better than all other models for predicting the maximum deflection of SPSWs under explosive loads. Findings The resistance of SPSW under explosive loads is evaluated using nonlinear FE analysis and surrogate methods. This study uses the CONWEP model for the explosive load and the Johnson-Cook model for the steel plate. Based on the Taguchi method, 25 samples out of 100 samples are selected for a parametric study where we predict the damaged zones and the maximum deflection of SPSWs under explosive loads. Then, this study uses a MLR, MLnER, GEP, ANFIS and an ensemble model to predict the maximum detection of SPSWs. Several statistical parameters and error terms are used to evaluate the accuracy of the different surrogate models. The results show that the cross-section in the y-direction and the plate thickness have the most significant effects on the maximum deflection of SPSWs. The results also show that the maximum deflection is related to the scaled distance, i.e. for a value of 0.383. The ensemble model performs better than all other models for predicting the maximum deflection of SPSWs under explosive loads. Originality/value The resistance of SPSW under explosive loads is evaluated using nonlinear FE analysis and surrogate methods. This study uses the CONWEP model for the explosive load and the Johnson-Cook model for the steel plate. Based on the Taguchi method, 25 samples out of 100 samples are selected for a parametric study where we predict the damaged zones and the maximum deflection of SPSWs under explosive loads. Then, this study uses a MLR, MLnER, GEP, ANFIS and an ensemble model to predict the maximum detection of SPSWs. Several statistical parameters and error terms are used to evaluate the accuracy of the different surrogate models. The results show that the cross-section in the y-direction and the plate thickness have the most significant effects on the maximum deflection of SPSWs. The results also show that the maximum deflection is related to the scaled distance, i.e. for a value of 0.383. The ensemble model performs better than all other models for predicting the maximum deflection of SPSWs under explosive loads.

Analysis of numerical calculation of elastic-plastic shell collapse with growing instability

The paper presents research of the collapse of the elastic-plastic shell under external surface forces simulating explosive loading by mathematical simulation using numerical methods. The problem was solved in two-dimensional curved geometries as a non-stationary problem of continuum mechanics. We applied the Wilkins Lagrangian method. The instability of the shell was initiated by harmonic surface perturbations on the outer or inner surfaces. The characteristics of the explosive loading were also changed: the maximum pressure, pressure fall time constant, and the time of application of the explosive load. The size of instability was determined by the deviation of the disturbed surface or the boundary of the jet-forming layer from the cylindrical one. We have established the parameters of the shell and the impulse loading on the shell, which affect most strongly the growth of instability during collapse.

Study of the Growth Process of Original Crack in the Surrounding Rock of Tunnel under the Adjacent Explosive Load

The surrounding rock damage of a tunnel under adjacent explosive load is often manifested as the growth of the original crack. In order to thoroughly understand the crack growth mechanism, in this study, the growth process of the original crack was investigated in detail by the dynamic caustics experiment. The experimental study shows that the growth of original crack is the result of the combined action of explosion stress wave and explosive gas. The quasi-static stress generated by the explosive gas was superimposed on the weakened stress field, resulting in the formation of the peak of the main stress difference in the surrounding rock, moving towards the adjacent tunnel in the form of an arc wave. With the arc wave moving towards the original crack, the growth rate of the original crack increases rapidly. During the period of 200 μs to 250 μs, the crack growth rate oscillates at the peak, and its size is approximately equal to the moving speed of the arc wave. Based on the experimental results and microscopic damage mechanics, the high stress concentration at the original crack tip under the stress wave first causes damage localization and the weakest chain is formed by the penetration of the damage localization zones by microcracks by special distribution law. Subsequently, the original crack starts to initiate and grow along the direction of the weakest chain.

Review of Safety Requirements Regarding Trading and Storing of Pyrotechnical Articles in Poland

Aim: The objective of the paper was to identify and analyse relevant requirements regarding the safety of storage and usage of pyrotechnic materials, intended for civil use. The review was based on binding applicable Polish and European legal acts. The results of the review pointed to the ambiguity of the provisions regulating the issues of safe usage and storage of pyrotechnical materials. Introduction: Some pyrotechnic articles, when triggered by a proper impulse, can lead to a violent reaction resulting in the release of a large amount of heat, and the creation of a blast wave. The effects of this reaction have a destructive impact on buildings situated nearby and pose a hazard to human life. Use and storage of pyrotechnic articles against the set rules is associated with the risk of fire or explosion, therefore a number of requirements have been introduced in this area. Methodology: In Poland there are many legal acts applicable to explosives. One of the most important one is the Act of 21 June 2002 on explosives designated for civil use, which presents pyrotechnic materials with respect to the safety of their usage and storage. Several key requirements have also been specified in agreements ratified in Poland and in other international acts, such as for example: the European Agreement concerning the International Carriage of Dangerous Goods by Road(ADR), and the Directive of the European Parliament and of the Council 2013/29/EU of 12 June 2013 on the harmonisation of laws of the Member States relating to the making available on the market of pyrotechnic articles. Results: It was established that there is a need of adopting a legal solution for storing pyrotechnical products for temporary sales in containers located near commercial facilities (and serving as back-up facilities). Although the regulations are not clear-cut, such a solution is used in practice, thus it would be advisable to determine by means of legal acts whether it is permissible and what requirements should be fulfilled, for example by a container, in which pyrotechnic articles are temporarily stored. Conclusions: The specification presented in the article allows to see the need to minimize the hazards associated with the marketing of pyrotechnical materials and justifies the necessity of adopting a particularly diligent classification and use of nomenclature for these products. In case of storing pyrotechnical materials, it is erroneous to adopt the determination of class “G” for two variable of net mass values of the explosive (when determining safe distances for explosive storage facilities, including among others class 1, sub-classes 1.3, 1.4). The same applies to the hexogen equivalent of an explosive load (when determining safe distances for explosive storage facilities including class 1, sub-classes 1.1, 1.5 and 4.1). Such provisions are misleading and may cause erroneous interpretations of regulations.