Experimental and numerical investigation of the dynamic response of structures subjected to underwater explosion

Wang

Sci. China Technol. Sci.

et al. 2019

A process of underwater explosion of a charge near a rigid wall includes three main stages: charge detonation, bubble pulsation and jet formation. A smoothed particle hydrodynamics (SPH) method has natural advantages in solving problems with large deformations and is suitable for simulation of processes of charge detonation and jet formation. On the other hand, a boundary element method (BEM) is highly efficient for modelling of the bubble pulsation process. In this paper, a hybrid algorithm, fully utilizing advantages of both SPH and BEM, was applied to simulate the entire process of free and near-field underwater explosions. First, a numerical model of the free-field underwater explosion was developed, and the entire explosion processfrom the charge detonation to the jet formation-was analysed. Second, the obtained numerical results were compared with the original experimental data in order to verify the validity of the presented method. Third, a SPH model of underwater explosion for a column charge near a rigid wall was developed to simulate the detonation process. The results for propagation of a shock wave are in good accordance with the physical observations. After that, the SPH results were employed as initial conditions for the BEM to simulate the bubble pulsation. The obtained numerical results show that the bubble expanded at first and then shrunk due to a differences of pressure levels inside and outside it. Here, a good agreement between the numerical and experimental results for the shapes, the maximum radius and the movement of the bubble proved the effectiveness of the developed numerical model. Finally, the BEM results for a stage when an initial jet was formed were used as initial conditions for the SPH method to simulate the process of jet formation and its impact on the rigid wall. The numerical results agreed well with the experimental data, verifying the feasibility and suitability of the hybrid algorithm. Besides, the results show that, due to the effect of the Bjerknes force, a jet with a high speed was formed that may cause local damage to underwater structures.

Section: Introductionmentioning

confidence: 99%

SPH-BEM simulation of underwater explosion and bubble dynamics near rigid wall

Wang

Sci. China Technol. Sci.

et al. 2019

Mathematical Problems in Engineering

“…The three cylindrical shell structures were unstiffened, internally stiffened, and externally stiffened, respectively. Li and Rong [12] studied the dynamic response of the cylindrical shell structures subjected to underwater explosion by using experimental and numerical methods. Li et al [13] investigated two kinds of the cylindrical shell models with the same geometry characteristics: unfilled and main hull sand-filled.…”

Section: Introductionmentioning

confidence: 99%

An Analytical Approach for Deformation Shapes of a Cylindrical Shell with Internal Medium Subjected to Lateral Contact Explosive Loading

Liang

2015

An experimental investigation on deformation shape of a cylindrical shell with internal medium subjected to lateral contact explosion was carried out briefly. Deformation shapes at different covered width of lateral explosive were recovered experimentally. Based on the experimental results, a corresponding analytical approach has been undertaken with rigid plastic hinge theory. In the analytical model, the cylindrical shell is divided into end-to-end rigid square bars. Deformation process of the cylindrical shell is described by using the translations and rotations of all rigid square bars. Expressions of the spring force, buckling moment, and deflection angle between adjacent rigid square bars are conducted theoretically. Given the structure parameters of the cylinder and the type of the lateral explosive charge, deformation processes and shapes are reported and discussed using the analytical approach. A good agreement has been obtained between calculated and experimental results, and thus the analytical approach can be considered as a valuable tool in understanding the deformation mechanism and predicting the deformation shapes of the cylindrical shell with internal medium subjected to lateral contact explosion. Finally, parametric studies are carried out to analyze the effects of deformation shape, including the covered width of the lateral explosive, explosive charge material, and distribution of initial velocity.

“…The modeling of composite shell and experiment tunnel is shown in Fig.2. During the simulation, the explosion source is simplified as a spherical TNT explosive [5,6]. It was set a certain distance away from the composite shell, and installed in the tunnel center.…”

Section: Composite Shell Simulation Modelingmentioning

confidence: 99%

Response Analysis of Composite Shell with Various Fixation Patterns under Axial Impact Load in Tunnel

Song¹,

Wei²

2017

dteees

Abstract. The safety equipment will against the explosive load when a disaster occurs in tunnel. This analysis of composite shell establishes a model of the relation among initial velocity, explosive load, plastic strain and shell fixation pattern, which is used to study the plastic strain of composite shell under different fixation patterns. The result shows that the fixation pattern plays a great part in the plastic strain of composite shells under axial impact load in tunnel. It is clearly that the extreme value and distribution range of plastic strain can be controlled by changing the fixation pattern. If the fixed point of composite shell is axisymmetric, the extreme value of plastic strain will decrease. Meanwhile, the distribution ranges of it remaining the same level. It is also confirmed that the plastic strain of fixed area which is far away from the explosion is more sensitive than the closer one to impact load.