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.

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.

Probabilistic Risk Prediction of Submarine Pipelines Subjected to Underwater Explosion Shock

1999 ◽  
Vol 121 (4) ◽  
pp. 251-254 ◽  
Author(s):  
Z. Zong ◽  
K. Y. Lam ◽  
G. R. Liu
Keyword(s):  
Shock Loading ◽  
Simple Procedure ◽  
Underwater Explosion ◽  
Coupling Model ◽  
Oil Pipeline ◽  
Structure Interaction ◽  
The Monte Carlo Method ◽  
Underwater Shock ◽  
Interaction Problem ◽  
Failure Probabilities

A simple procedure is proposed in this paper to estimate the global failure probabilities of a submarine oil pipeline subjected to underwater explosion shock wave. The deterministic response of a pipeline subjected to an underwater shock loading is first given by solving a simplified fluid-structure interaction problem. Compared with an FEM/BEM coupling model, the present method gives good results at much lower computational efforts. Then, the Monte Carlo method is used to find the global failure probabilities of the pipeline. Finally, a practical example is given.

scholarly journals Effect of Bottom Geometry on the Natural Sloshing Motion of Water Inside Tanks: An Experimental Analysis

2021 ◽  
Vol 11 (2) ◽  
pp. 605
Author(s):  
Antonio Agresta ◽  
Nicola Cavalagli ◽  
Chiara Biscarini ◽  
Filippo Ubertini
Keyword(s):  
Energy Dissipation ◽  
Water Depth ◽  
Shear Force ◽  
Experimental Tests ◽  
Shear Load ◽  
Damping Properties ◽  
Base Shear ◽  
Structure Interaction ◽  
Sloshing Phenomenon ◽  
Key Aspects

The present work aims at understanding and modelling some key aspects of the sloshing phenomenon, related to the motion of water inside a container and its effects on the substructure. In particular, the attention is focused on the effects of bottom shapes (flat, sloped and circular) and water depth ratio on the natural sloshing frequencies and damping properties of the inner fluid. To this aim, a series of experimental tests has been carried out on tanks characterised by different bottom shapes installed over a sliding table equipped with a shear load cell for the measurement of the dynamic base shear force. The results are useful for optimising the geometric characteristics of the tank and the fluid mass in order to obtain enhanced energy dissipation performances by exploiting fluid–structure interaction effects.

Evidence of soil-structure interaction from modular full-scale field experimental tests

2021 ◽  
Author(s):  
Athanasios Vratsikidis ◽  
Dimitris Pitilakis ◽  
Anastasios Anastasiadis ◽  
Anastasios Kapouniaris
Keyword(s):  
Soil Structure ◽  
Experimental Tests ◽  
Full Scale ◽  
Soil Structure Interaction ◽  
Structure Interaction ◽  
Scale Field

Experimental and Numerical Plastic Response and Failure of Laterally Impacted Rectangular Plates

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
B. Liu ◽  
R. Villavicencio ◽  
C. Guedes Soares
Keyword(s):  
Finite Element ◽  
Numerical Simulations ◽  
Failure Modes ◽  
Mesh Size ◽  
Plastic Behavior ◽  
Finite Element Models ◽  
Rectangular Plates ◽  
Marine Structures ◽  
Fine Mesh ◽  
The Impact

Experimental and numerical results of drop weight impact test are presented on the plastic behavior and fracture of rectangular plates stuck laterally by a mass with a hemispherical indenter. Six specimens were tested in order to study the influence of the impact velocity and the diameter of the indenter. The impact scenarios could represent abnormal actions on marine structures, such as ship collision and grounding or dropped objects on deck structures. The tests are conducted on a fully instrumented impact tester machine. The obtained force-displacement response is compared with numerical simulations, performed by the LS-DYNA finite element solver. The simulations aim at proposing techniques for defining the material and restraints on finite element models which analyze the crashworthiness of marine structures. The mesh size and the critical failure strain are predicted by numerical simulations of the tensile tests used to obtain the mechanical properties of the material. The experimental boundary conditions are modeled in order to represent the reacting forces developed during the impact. The results show that the critical impact energy until failure is strongly sensitive to the diameter of the striker. The shape of the failure modes is well predicted by the finite element models when a relatively fine mesh is used. Comments on the process of initiation and propagation of fracture are presented.

Dynamic Plastic Response of Cylindrical Shells Under Gaussian Impulse

1980 ◽  
Vol 24 (01) ◽  
pp. 24-30
Author(s):  
S. Anantha Ramu ◽  
K. J. Iyengar
Keyword(s):  
Cylindrical Shells ◽  
Yield Condition ◽  
Longitudinal Axis ◽  
Plastic Behavior ◽  
Plastic Response ◽  
Marine Structures ◽  
Impulsive Load ◽  
Tresca Yield Condition ◽  
Impulsive Loads

The determination of the inelastic response of cylindrical shells under general impulsive loads is of relevance to marine structures such as submarines, in analyzing their slamming damages. The present study is concerned with the plastic response of a simply supported cylindrical shell under a general axisymmetric impulsive load. The impulsive load is assumed to impart an axisymmetric velocity to the shell, with a Gaussian distribution along the longitudinal axis of the shell. A simplified Tresca yield condition is used. The shell response is determined for various forms of impulses ranging from a concentrated impulse to a uniform impulse over the entire length of the shell. Conclusions about the influence of geometry of the shell and the spatial distribution of impulse on the plastic behavior of cylindrical shells are presented.

Influence of Rock Plastic Behavior on the Wellbore Stability

2021 ◽  
Author(s):  
Elena Grishko ◽  
Aboozar Garavand ◽  
Alexey Cheremisin
Keyword(s):  
Failure Criteria ◽  
Wellbore Stability ◽  
Standard Approach ◽  
Plastic Behavior ◽  
Element Formulation ◽  
Geomechanical Model ◽  
Plastic Properties ◽  
Plastic Deformations ◽  
3D Geomechanical Model

Abstract Currently, the standard approach to building a geomechanical model for analyzing wellbore stability involves taking into account only elastic deformations. This approach has shown its inconsistency in the design and drilling of wells passing through rocks with pronounced plastic properties. Such rocks are characterized by the fact that when the loads acting on them change, they demonstrate not only elastic, but also plastic (irreversible) deformations. Plastic deformations have an additional impact on the distribution of stresses in the rock of the near-wellbore zone on a qualitative and quantitative level. Since plastic deformations are not taken into account in the standard approach, in this case the results of the wellbore stability analysis are based on incorrectly calculated stresses acting in the rock. As a result, it can lead to misinterpretation of the model for analysis, suboptimal choice of trajectory, incorrect calculation of safe mud window and an incorrectly selected set of measures to reduce the risks of instability. The aim of this work is to demonstrate the advantages of the developed 3D elasto-plastic program for calculating the wellbore stability in comparison with the standard elastic method used in petroleum geomechanics. The central core of the work is the process of initialization of the elasto-plastic model according to the data of core tests and the subsequent validation of experimental and numerical loading curves. The developed 3D program is based on a modified Drucker-Prager model and implemented in a finite element formulation. 3D geomechanical model of wellbore stability allows describing deformation processes in the near-wellbore zone and includes the developed failure criteria. The paper shows a special approach to the determination of the mud window based on well logging data and core tests by taking into account the plastic behavior of rocks. An important result of this study is the determination of the possibility of expanding the mud window when taking into account the plastic criterion of rock failure.

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.

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