Conditions for guaranteed destruction and explosion resistance of beam structural elements in the event of an explosion in water

По данным проведенных ранее исследований авторов найдены условия гарантированного разрушения и гарантированной взрывостойкости балки, свободно лежащей на недеформируемых опорах в воде. Импульсная динамическая нагрузка создана взрывом сосредоточенного заряда конденсированного взрывчатого вещества (ВВ), расположенного в воде на фиксированном расстоянии от балки. Под разрушением понимается потеря несущей способности балки вследствие возникновения в ней пластических зон (шарниров), трещин, разделений на фрагменты. Использован обобщенный на действия динамической нагрузки критерий разрушения, основанный на достижении максимальным изгибающим моментом критических значений. According to the data of the authors’ earlier studies, the conditions of guaranteed destruction and guaranteed explosion resistance of a beam freely lying on non-deformable supports in water were found. The impulse dynamic load is created by the explosion of a concentrated charge of a condensed explosive (HE) located in water at a fixed distance from the beam. Destruction is understood as the loss of the bearing capacity of the beam due to the appearance of plastic zones (hinges), cracks, and fragmentation in it. The criterion of destruction generalized to the action of dynamic load is used, based on the achievement of critical values by the maximum bending moment.

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.

Estimating the consequences of an explosion on critical infrastructure

The study is an analysis estimating the threat arising from the detonation products of a condensed explosive on the physical environment. It presents an analysis of fundamental detonation properties such as detonation height and Mach wave formation, related to their loading effects on critical infrastructure. Analytical equations as well as modelling were investigated to predict the effects of explosive loading on surroundings and people. Comparisons were made between the results from calculations with those of the equations, based on approximated experimental data. It was concluded that when applying the JWL equation of state to the reaction products of TNT, good agreement was obtained between modeling and experimental results for the detonation energy derived with the aid of thermodynamic calculations.

Simulation of one dimension shock initiation of condensed explosive by SPH method

Purpose This paper aims to study the ability of SPH method in simulating shock initiation process. The initiation and subsequent explosion processes of condensed explosive involve high pressure propagation and material large deformation, which increase the simulation difficulty in using traditional mesh-based method. The study aims to take the SPH method as an alternative method to shock initiation simulation. Design/methodology/approach The SPH method combined with some correct aspects is applied to simulate the shock initiation process. The condensed explosive is ignited by the impact of high speed flyer. In order to avoid the non-physical penetration between particles of high velocity flyer and condensed explosive, a particle-to-particle contact algorithm is employed. After the ignition, the detonation process of condensed explosive is represented by the ignition and growth model. A modified SPH method based on Riemann-solver is applied to smooth the numerical oscillation at shock front. Two numerical examples are implemented to illustrate the capability of SPH method in shock initiation simulation. One is the interface velocity experiment of PBX-9501. Another is the plate push experiment of PBX-9502. Both of the examples include the shock initiation process of condensed explosive. Findings Numerical results show that the shock initiation process of condensed explosive can be well predicted by SPH method. The characteristics of detonation are captured in the simulation. The measured data in numerical examples are also in good agreement with the experimental data. Research limitations/implications Because of the research purpose is to study the ability of SPH for shock initiation simulation, only one-dimension numerical examples are discussed in the paper. Therefore, researchers are encouraged to extend and test the proposed method to two or three dimension shock initiation problems simulation. Originality/value This paper provides an alternative method for shock initiation simulation. The implemented method can overcome the weaknesses of traditional mesh based method in simulation of shock initiation problems.

THREE-DIMENSIONAL SIMULATION OF CONDENSED EXPLOSIVE-INDUCED FLOW PROPAGATION AND INTERACTION WITH GLASS CURTAIN WALL

In order to carry out blast response of curtain wall, the first step is to understand the complex flow of the air blasts around the structures and predict the blast loads acting on the structures. But in earlier studies related to blast resistant design of glass curtain wall, blast flow induced by condensed explosive is not taken into account due to expensively computational resources required. Based on high performance computing, this paper presents a new three-dimensional numerical simulation method of condensed explosive-induced flow propagation and impact on a complex glass curtain wall, where the fluid is represented by solving Navier–Stokes equations with a multimaterial arbitrary Lagrangian–Eulerian (ALE) formulation. In particular, the whole analytical model consists of condensed explosive, air, detailed curtain wall system, and ground, which comprehensively represents the real fluid–structure interaction environment. Final calculation has been performed on the Dawning 4000A supercomputer based on the domain decomposition method. The flow mechanisms of blast wave rounding curtain wall is visualized and the simulated pressure history of gauge is in good agreement with the experimental result which validates this method. The present method is shown to be a useful tool for blast resistance design of curtain wall in the future.