A computational framework for underwater shock response of marine structures

2015 ◽  
pp. 145-152
Keyword(s):  
Marine Structures ◽  
Computational Framework ◽  
Shock Response ◽  
Underwater Shock

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.

Transient Response of Submerged Plates Subject to Underwater Shock Loading: An Analytical Perspective

2008 ◽  
Vol 75 (4) ◽  
Author(s):  
Zhanke Liu ◽  
Yin L. Young
Keyword(s):  
Structural Dynamics ◽  
Transient Response ◽  
Shock Loading ◽  
Structural Response ◽  
Small Range ◽  
Pressure Loading ◽  
Structure Interaction ◽  
Shock Response ◽  
Analytical Perspective ◽  
Underwater Shock

In this paper, Taylor’s floating air-backed plate (ABP) model is extended to the case of a submerged water-backed plate (WBP) within the acoustic range. The solution of the WBP is cast into the same format as that of the ABP with a modified fluid-structure interaction (FSI) parameter, which allows a unified analysis of the ABP and WBP using the same set of formulas. The influence of back conditions on fluid and structural dynamics, including fluid cavitation, is systematically investigated. Asymptotic limits are mathematically identified and physically interpolated. Results show that the WBP experiences lower equivalent pressure loading, reduced structural response, and hence lower peak momentum gaining. The time to reach peak momentum is shorter for the WBP than for the ABP. Cavitation is found to be almost inevitable for the ABP, while relevant to the WBP only for a small range of the FSI parameter. Implications to shock response of submerged structures are briefly discussed.

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 Computational Treatments of Cavitation Effects in Near-Free-Surface Underwater Shock Analysis

2001 ◽  
Vol 8 (2) ◽  
pp. 105-122 ◽  
Author(s):  
Michael A. Sprague ◽  
Thomas L. Geers
Keyword(s):  
Free Surface ◽  
Finite Elements ◽  
Plane Wave ◽  
Single Layer ◽  
Wave Radiation ◽  
Large Array ◽  
Shock Response ◽  
Underwater Shock ◽  
Wet Surface ◽  
Fundamental Limitation

Fluid cavitation constitutes an expensive computational nuisance in underwater-shock response calculations for structures at or just below the free surface. In order to avoid the use of a large array of cavitating acoustic finite elements (CAFE), various wet-surface approximations have been proposed. This paper examines the performance of two such approximations by comparing results produced by them for 1-D canonical problems with corresponding results produced by more rigorous CAFE computations. It is found that the fundamental limitation of wet-surface approximations is their inability to capture fluid-accretion effects. As an alternative, truncated CAFE fluid meshes with plane-wave radiation boundaries are shown to give good results. In fact, a single layer of CAFE is found to be comparable in accuracy to the better of the wet-surface approximations. The paper concludes with an examination of variations in CAFE modeling.

Three-Dimensional Underwater Shock Response of Composite Marine Structures

2011 ◽  
Vol 78 (6) ◽  
Author(s):  
Michael R. Motley ◽  
Yin L. Young ◽  
Zhanke Liu
Keyword(s):  
Composite Structures ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Aluminum Bronze ◽  
Marine Structures ◽  
Initial Failure ◽  
Shock Response ◽  
Failure Loads ◽  
Structural Responses ◽  
Marine Applications

In recent years, there has been an increased interest in the use of advanced composites in marine applications. It has been shown that by exploiting the inherent anisotropic nature of the material, fiber-reinforced composite structures can be tailored to allow automatic, passive, three-dimensional (3D) adaptive/morphing capabilities such that they outperform their rigid counterparts both hydrodynamically and structurally. Much of the current research on the shock response of composite structures focuses on air-backed structures with fixed-fixed or simply supported boundary conditions. Nevertheless, many critical components of marine structures where adaptive/morphing capabilities are needed are cantilevered-type structures, including propeller and turbine blades, hydrofoils, and rudders. This paper investigates the 3D transient response of cantilevered, anisotropic, composite marine structures, namely, fully submerged cantilevered plates, subject to a range of shock loads. Structural responses and the initial failure loads of a composite plate are compared with a nickel-aluminum-bronze plate. Discussions of the fluid and structural responses of both materials are presented, and the initial failure loads of both materials are compared.

scholarly journals A Computer Program for a Canonical Problem in Underwater Shock

1994 ◽  
Vol 1 (4) ◽  
pp. 331-337 ◽  
Author(s):  
Thomas L. Geers ◽  
Teh-Hua Ju
Keyword(s):  
Computer Program ◽  
Closed Form Solution ◽  
Form Solution ◽  
Marine Structures ◽  
Underwater Explosions ◽  
Generalized Fourier Series ◽  
Method Of Solution ◽  
Underwater Shock ◽  
Acoustic Fluid ◽  
Element Boundary

Finite-element/boundary-element codes are widely used to analyze the response of marine structures to underwater explosions. An important step in verifying the correctness and accuracy of such codes is the comparison of code-generated results for canonical problems with corresponding analytical or semianalytical results. At the present time, such comparisons rely on hardcopy results presented in technical journals and reports. This article describes a computer program available from SAVIAC that produces user-selected numerical results for a step-wave-excited spherical shell submerged in and (optionally) filled with an acoustic fluid. The method of solution employed in the program is based on classical expansion of the field quantities in generalized Fourier series in the meridional coordinate. Convergence of the series is enhanced by judicious application of modified Cesàro summation and partial closed-form solution.

Transient underwater shock response of sacrificed coating with continuous density graded foam core

2016 ◽  
Vol 98 ◽  
pp. 297-307 ◽  
Author(s):  
Y. Chen ◽  
F. Chen ◽  
W. Zhang ◽  
Z.P. Du ◽  
H.X. Hua
Keyword(s):  
Foam Core ◽  
Continuous Density ◽  
Shock Response ◽  
Underwater Shock
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