The scaling laws of cabin structures subjected to internal blast loading:Experimental and numerical studies

This paper presents a combination of experimental and numerical investigations on the dynamic response of scaling cabin structures under internal blast loading.The purpose of this study is to modify the similar relationship between the scaled-down model and the prototype of the cabin structures under internal blast loading.According to the Hopkinson’s scaling law,three sets of cabin structure models with different scaling factors combined with different explosive masses were designed for the experimental study.The dynamic deformation process of the models was recorded by a three-dimensional digital imaging correlation(DIC)method and a 3D scanning technology was used to reconstruct the deformation modes of the specimen.In addition,a finite element model was developed for the modification of the scaling law.The experimental results showed that the final deflection-to-thickness ratio was increased with the increase of the model size despite of the similar trend of their deformation processes.The reason for this inconsistency was discussed based on the traditional scaling law and a modified formula considering of the effects of size and strain-rate was provided.

Numerical Simulation of Dynamic Response of an Existing Subway Station Subjected to Internal Blast Loading

In order to design and retrofit a subway station to resist an internal blast, the distribution of blast loading and its effects on structures should be investigated firstly. In this paper, the behavior of a typical subway station subjected to different internal blast Ioadings was analyzed. It briefly introduced the geometric characteristics and material constitutive model of an existing two-layer and three-span frame subway station. Then three cases of different explosive charges were consid- ered to analyze the dynamic responses of the structure. Finally, the maximum principal stress, dis- placement and velocity of the columns in the three cases were obtained and discussed. It con- cluded that the responses of the columns are sensitive to the charge of explosive and the distance from the detonation. It＇s also found that the stairs between the two layers have significant effects on the distribution of the maximum principal stress of the columns in the upper layer. The explicit dynamic nonlinear finite element software ANSYS/LS-DYNA was used in this study.

Influence of explosive density on small scale internal blast experiments

To study the internal blast load, a lot of small scale internal blast experiments have been conducted. For those experiments, the influence of explosive density generally was not taken into account while it was simple to have slight density differences in application. To analyze the influence of explosive density on small scale internal blast experiments, the finite element code LS-DYNA was employed and the numerical model was established. The numerical model was validated against published experimental data and the result shows a good agreement. We found that that both the peak overpressure and impulse increase with the density of charge. Empirical equations were fitted using the calculation results to evaluate the influence of explosive density on the peak overpressures and impulses.

Effective Impulse for Fully Clamped Rectangular Plates Under Internal Blast Loading

Under internal blast loading,the response of a beam or plate is highly correlated with the phenomenon of saturated impulse,which governs the deflection of the structure.This paper aims to investigate the phenomenon of saturated impulse for fully clamped rectangular plates subjected to internal blast loading.Based on the rigid,perfectly plastic assumption,the relationship between saturation duration and saturation deflection is derived.Influences of the peak shock wave,the duration of shock wave and the peak quasi-static pressure loading on saturation duration and saturation deflection are discussed.It is found that there is a critical duration for the internal blast impulse to reach saturation,and beyond this duration,the deflection of plate will no longer increase as the loading increases further.The saturation deflection and saturation duration both exhibit regular variation patterns with the changes of the dimensionless peak shock wave,the duration of shock wave and the peak quasi-static pressure loading.