Dynamic Hydroelastic Scaling of the Underwater Shock Response of Composite Marine Structures

2011 ◽  
Vol 79 (1) ◽  
Author(s):  
Erin E. Bachynski ◽  
Michael R. Motley ◽  
Yin L. Young
Keyword(s):  
Underwater Explosion ◽  
Elastic Beam ◽  
Initial Response ◽  
Scaling Relations ◽  
Scaling Analysis ◽  
Marine Structures ◽  
Finite Element Software ◽  
Anisotropic Composite ◽  
Shock Response ◽  
Underwater Shock

The hydroelastic scaling relations for the shock response of water-backed, anisotropic composite marine structures are derived and verified. The scaling analysis considers the known underwater explosion physics, previously derived analytical solutions for the underwater shock response of a water-backed plate, and elastic beam behavior. To verify the scaling relations, the hydroelastic underwater shock response of an anisotropic composite plate at several different scales is modeled as a fully coupled fluid-structure interaction (FSI) problem using the commercial Lagrangian finite element software ABAQUS/Explicit. Following geometric and Mach similitude, as well as proper scaling of the FSI parameter, scaling relations for the structural natural frequencies, fluid and structural responses are demonstrated for a variety of structural boundary conditions (cantilevered, fixed-fixed, and pinned-pinned). The scaling analysis shows that the initial response scales properly for elastic marine structures, but the secondary bubble pulse reload caused by an underwater explosion does not follow the same scaling and may result in resonant response at full scale.

Dynamic Viscoplastic Response of a Circular Plate Subjected to Underwater Shock

2012 ◽  
Vol 56 (02) ◽  
pp. 71-79
Author(s):  
Z. Zong ◽  
Y. F. Zhang ◽  
L. Zhou
Keyword(s):  
Circular Plate ◽  
Underwater Explosion ◽  
Experimental Tests ◽  
Correct Prediction ◽  
Plastic Behavior ◽  
Marine Structures ◽  
Plastic Deformations ◽  
Structure Interaction ◽  
Double Phase ◽  
Underwater Shock

A structure subjected to underwater shock exhibits surprising dynamic behavior, different from the permanent plastic deformation of a structure subjected to air blast, due to the presence of complicated fluid-structure interaction (FSI) effect. Previous studies of a circular plate subjected to underwater shock indicate that there exist large discrepancies between theoretical and experimental results of plastic deformations. Herein we thus propose a new double-scale and double-phase (DSDP) FSI model for correct prediction of the dynamic plastic behavior of a circular plate subjected to underwater shock. Results obtained from this DSDP model are compared with several experimental tests, with excellent agreement observed. This model is believed useful for further implementation in those software programs that handle underwater explosion and its effects on marine structures.

scholarly journals Numerical Simulation and Response of Stiffened Plates Subjected to Noncontact Underwater Explosion

2014 ◽  
Vol 2014 ◽  
pp. 1-17 ◽  
Author(s):  
Elsayed Fathallah ◽  
Hui Qi ◽  
Lili Tong ◽  
Mahmoud Helal
Keyword(s):  
Numerical Simulation ◽  
Underwater Explosion ◽  
Design Guidelines ◽  
Nonlinear Finite Element ◽  
Steel Plates ◽  
Stiffened Plates ◽  
Shock Loads ◽  
Floating Structures ◽  
Underwater Shock ◽  
Overall Performance

A numerical simulation has been carried out to examine the response of steel plates with different arrangement of stiffeners and subjected to noncontact underwater explosion (UNDEX) with different shock loads. Numerical analysis of the underwater explosion phenomena is implemented in the nonlinear finite element code ABAQUS/Explicit. The aim of this work is to enhance the dynamic response to resist UNDEX. Special emphasis is focused on the evolution of mid-point displacements. Further investigations have been performed to study the effects of including material damping and the rate-dependant material properties at different shock loads. The results indicate that stiffeners configurations and shock loads affect greatly the overall performance of steel plates and sensitive to the materials data. Also, the numerical results can be used to obtain design guidelines of floating structures to enhance resistance of underwater shock damage, since explosive tests are costly and dangerous.

High Pressure Generation Using Underwater Explosion of a Spiral Explosive in a Conical Vessel

2004 ◽  
Vol 126 (2) ◽  
pp. 258-263
Author(s):  
Toru Hamada ◽  
Shigeru Itoh ◽  
Kenji Murata ◽  
Yukio Kato
Keyword(s):  
Shock Wave ◽  
Characteristic Curve ◽  
Three Dimensional ◽  
Underwater Explosion ◽  
Initial Pressure ◽  
Maximum Pressure ◽  
Underwater Shock Wave ◽  
Expansion Curve ◽  
Underwater Shock ◽  
Manganin Gauge

An explosive configuration was studied so that the underwater shock wave converges at the tip of the explosive, and a three-dimensional spiral configuration was obtained. This spiral configuration need to be analyzed theoretically due to the relation of propagation velocity of underwater shock wave, detonation velocity of the explosive and a configuration of vessel to charge the explosive. In order to study an effect of the convergence, pressure measurement at the spiral center was carried out by using a manganin gauge. Therefore, when SEP was used in this experiment, the maximum pressure value was 17.7 GPa. This maximum pressure value is higher than the pressure value of underwater shock wave generated from the underwater explosion of a straight configuration. Furthermore, this maximum pressure value was higher than C-J pressure of SEP. An initial pressure of underwater shock water shock wave that can obtain from an isentropic expansion curve of SEP and a characteristic curve of water is 5.7 GPa, and C-J pressure of SEP is 15.9 GPa. From the above-mentioned, the effect of spiral convergence could be shown well.

The Transient Response of Imperfect Thin-Walled Stiffened Cylindrical Shell Exposed to Side-On Underwater Explosion

2009 ◽  
Author(s):  
Ching-Yu Hsu ◽  
Chan-Yung Jen
Keyword(s):  
Cylindrical Shell ◽  
Transient Response ◽  
Cylindrical Shells ◽  
Underwater Explosion ◽  
Stiffened Cylindrical Shell ◽  
Analysis And Design ◽  
Finite Element Software ◽  
Pressure Load ◽  
Thin Walled ◽  
Stiffened Cylindrical Shells

The thin-walled stiffened cylindrical shells are usually applied in a submarine which takes the external pressure load, or in a boiler, pressure vessel or pipeline system which takes the internal pressure load. The thin-walled stiffened cylindrical shells under hydrodynamic loading are very sensitive to geometrical imperfections. This study is investigating an imperfect thin-walled stiffened cylindrical shell (out-of-round ratio is ψ = 2%) at a depth of 50m below the water level to see how it withstands sideward TNT 782 kg underwater explosion loading so as to understand its structural transient response. ABAQUS finite element software is used as an analysis tool in the current study, meanwhile, during the analysis process, the Fluid-Structure Interaction (FSI) condition is employed. The structural transient response results of stress and displacement time history of the imperfect thin-walled stiffened cylindrical shell can be used as a reference for the anti-underwater explosion analysis and design of future submersible vehicles, pressure hulls or related structural designs.

Effects of Steel Case on Underwater Shock Wave

2011 ◽  
Vol 52-54 ◽  
pp. 943-948
Author(s):  
Ji Li Rong ◽  
Da Lin Xiang ◽  
Jian Li
Keyword(s):  
Shock Wave ◽  
Peak Pressure ◽  
Underwater Explosion ◽  
Steel Shell ◽  
Cylindrical Charge ◽  
Underwater Shock Wave ◽  
Shock Wave Energy ◽  
Lag Effect ◽  
Underwater Shock ◽  
Different Thickness

The effects of steel case confinement for the aluminized explosive on underwater explosion(UNDEX) were experimentally and numerically investigated. The experimental results using 1kg cylindrical charge cased 6mm steel shell, show that steel case enhance the peak pressure, impulse, shock wave energy and decay time relative to the bare charge. The effect of different thickness of steel case was analyzed. With the increase of the case thickness, the shock wave were enhanced first and weaken later, and there is a lag-effect for the peak pressure of shock wave. There is an optimal case thickness which could maximum enhance the peak pressure. According to dimensional analysis, it's found that the ratio of case mass and charge mass( ) is a better dimensionless parameter to estimate UNDEX for a cased charge.

Shock Response of Ship Section to Underwater Explosion With the Cavitation Effect

2014 ◽  
Author(s):  
Chen Ying-yu ◽  
Xiongliang Yao ◽  
Xiao Wei ◽  
Liu Xiang-dong
Keyword(s):  
Simple Structure ◽  
Underwater Explosion ◽  
Pulse Load ◽  
Wave Load ◽  
Ship Structure ◽  
Structure Response ◽  
Cavitation Effect ◽  
Shock Response ◽  
Simulation Results ◽  
Structural Arithmetic

Besides the shock wave load and the gas bubble pulse load, cavitation effect has a significant influence on the ships subjected to underwater explosion. The goal of this research is to investigate the cavitation effect on the response of ship section using acoustic-structural arithmetic. Comparison between the structure response considering the cavitation effect and not, the formation mechanism of cavitation zone are discussed. The simulation results show acoustic-structural arithmetic can be used to numerical simulate the dynamic response of simple structure and ship section subjected to underwater explosion with the consideration of cavitation effect. And it also can be used to capture the cavitation in the water. Meanwhile, the simulation results show that cavitation zone generated by underwater explosion is very large, and the reloading effect is obvious with the consideration of cavitation effect. The vibration of the ship structure is more severe with the reloading, and thus more serious damage occurs as the result of the prolonged loading time.

scholarly journals Fundamental Characteristics of Underwater Shock Wave due to Underwater Explosion of High Explosives.

1996 ◽  
Vol 62 (601) ◽  
pp. 3278-3283
Author(s):  
Shigeru ITOH ◽  
You NADAMITSU ◽  
Akio KIRA ◽  
Shiro NAGANO ◽  
Masahiro FUJITA ◽  
...  
Keyword(s):  
Shock Wave ◽  
Underwater Explosion ◽  
High Explosives ◽  
Underwater Shock Wave ◽  
Underwater Shock
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