Optimal Configuration for Stiffened Plates under the Effect of Underwater Explosion

2015 ◽  
Vol 813 ◽  
pp. 161-168
Author(s):  
Fathallah Elsayed ◽  
Hui Qi ◽  
Li Li Tong ◽  
Mahmoud Helal
Keyword(s):  
Underwater Explosion ◽  
Optimal Configuration ◽  
Steel Plates ◽  
Floating Structure ◽  
Shock Loads ◽  
Finite Element Program ◽  
Explicit Finite Element ◽  
Element Program ◽  
Complex Fluid ◽  
Stiffened Steel

The dynamic response of a floating structure subjected to underwater explosion is greatly complicated by the explosion of a high explosive, propagation of shock wave, complex fluid–structure interaction phenomena, and the dynamic behavior of the floating structures. A numerical investigation has been carried out to examine the behavior of stiffened steel plates subjected to shock loads resulting from an Underwater Explosion (UNDEX). The aim of this work is to obtain the optimal configuration to resist underwater shock loading. A non-linear dynamic numerical analysis of the underwater explosion phenomena associated with different geometrical stiffened steel plates is performed using the ABAQUS/Explicit finite element program. Special emphasis is focused on the evolution of mid-point displacements. Further investigations have been performed to study the effect of including material damping and the rate-dependant material properties at different shock loads. The results indicate that stiffener configurations and shock loads affect greatly the overall performance of steel plates and sensitive to the material data.

Simulation of Responses of Liquid Filled Double Bottom Structures Subjected to a Closely Underwater Explosion Shock Loading

2011 ◽  
Vol 88-89 ◽  
pp. 662-667 ◽  
Author(s):  
Ting Tang ◽  
Li Jun Wang ◽  
Jin Bo Ma
Keyword(s):  
Finite Element ◽  
Shock Loading ◽  
Underwater Explosion ◽  
Finite Element Program ◽  
Explicit Finite Element ◽  
Comparative Analyses ◽  
Element Program ◽  
The Difference ◽  
Bottom Structures

The purpose of this work is to study the effect of liquid in double bottom structures subjected to a closely underwater explosion shock loading. The comparative analyses are made by use of a commercial, explicit finite element program. Based on the difference of depth of liquid in double bottom structures and distance between explosive and outer bottom, six cases were simulated in this paper. The results show that liquid in cabins can enhance the resistance of double bottom structures to an underwater explosion.

Passive Safety Analysis for the Commercial Vehicle Cab after Weight-Reduction Design

2015 ◽  
Vol 798 ◽  
pp. 48-52 ◽  
Author(s):  
Jing Chen ◽  
Hong Yin Wang ◽  
Qian Wang ◽  
Xiong Long Tao
Keyword(s):  
Weight Reduction ◽  
Strength Test ◽  
Commercial Vehicles ◽  
Finite Element Program ◽  
Explicit Finite Element ◽  
Wall Strength ◽  
Element Program ◽  
Roof Strength ◽  
Front Impact ◽  
Crash Tests

Lighter weight commercial vehicles facilitate faster transport, higher mobility and fuel conservation. Weight reduction and safety are mutually competing objectives. And the safety should not be compromised after weight reduction. Full size crash tests are expensive and time consuming to organize. Using a numerical simulation for predicting crash to the occupants’ safety can minimize the number of such trials. In this paper three virtual crash simulations for the three load cases: Front impact test, Roof strength test and Rear wall strength test are performed according to the European regulation ECE-R29. The explicit finite element program LS-DYNA is used for that purpose. The comparisons between simulation results and test data available in the literature are also presented in this paper.

Research on mechanical behavior of L-shaped multi-cell concrete-filled steel tubular stub columns under axial compression

2018 ◽  
Vol 22 (2) ◽  
pp. 427-443 ◽  
Author(s):  
Jiepeng Liu ◽  
Hua Song ◽  
Yuanlong Yang
Keyword(s):  
Finite Element ◽  
Compressive Strength ◽  
Bearing Capacity ◽  
Thickness Ratio ◽  
Steel Plates ◽  
Test Results ◽  
Finite Element Program ◽  
Element Program ◽  
Compressive Strength Of Concrete ◽  
Stub Columns

A total of 11 L-shaped multi-cell concrete-filled steel tubular stub columns were fabricated and researched in axial compression test. The key factors of width-to-thickness ratio D/ t of steel plates in column limb and prism compressive strength of concrete fck were investigated to obtain influence on failure mode, bearing capacity, and ductility of the specimens. The test results show that the constraint effect for concrete provided by multi-cell steel tube cannot be ignored. The ductility decreases with the increase of width-to-thickness ratio D/ t of steel plates in column limb. The bearing capacity increases and the ductility decreases with the increase in prism compressive strength of concrete fck. A finite element program to calculate concentric load–displacement curves of L-shaped multi-cell concrete-filled steel tubular stub columns was proposed and verified by the test results. A parametric analysis with the finite element program was carried out to study the influence of the steel ratio α, steel yield strength fy, prism compressive strength of concrete fck, and width-to-thickness ratio D/ t of steel plates in column limb on the stiffness, bearing capacity and ductility. Furthermore, the design method of bearing capacity was determined based on mainstream concrete-filled steel tubular codes.

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.

Virtual Testing for Frontal Impact of High-Top Cab of Heavy Truck

2011 ◽  
Vol 148-149 ◽  
pp. 1081-1084
Author(s):  
Wei Wang ◽  
Xu Liang Xie ◽  
Fu Lin Shen ◽  
Xiao Feng Wang
Keyword(s):  
Finite Element ◽  
Element Model ◽  
Front Seat ◽  
Finite Element Program ◽  
Explicit Finite Element ◽  
Commercial Code ◽  
Element Program ◽  
Heavy Truck ◽  
Survival Space ◽  
Pendulum Impact

ECE R29 regulation has legally claimed that the survival space must be guaranteed for the safety for driver and front seat passenger in event of crash during design of truck cabin. In this paper, a finite element model of a high-top cabin of a heavy truck with a manikin on the driver seat was built with commercial code Hypermesh, The explicit finite element program Ls-Dyna was used to simulate the frontal pendulum impact on the high-top cab in the light of ECE R29 regulation. Deformation of the truck cabin and the survival space of the dummy were analyzed and discussed. Also, some suggestions were given to solve the contact possibility between steering column and the knees of manikin.

An Experimental and Numerical Study to Analysis and Design of Sheet Hydroforming Process for an Automobile Fender Shell

2006 ◽  
Author(s):  
Mohammad Habibi Parsa ◽  
Payam Darbandi
Keyword(s):  
Finite Element ◽  
Numerical Study ◽  
Fluid Pressure ◽  
Finite Element Program ◽  
New Approach ◽  
Explicit Finite Element ◽  
Sheet Hydroforming ◽  
Analysis And Design ◽  
Hydroforming Process ◽  
Element Program

A new approach for manufacturing of shell fender is proposed and has been examined numerically and experimentally. The new suggested method is based on sheet hydroforming process, which has a lot of advantages over conventional deep drawing process. After defining the shape of initial blank using an inverse finite element program, numerical evaluation of the proposed sheet hydroforming process for production of shell fender has been carried out using an explicit finite element code considering fluid pressure, boundary conditions and tools. Then experimental evaluation has been carried out using down sized specimen and the results have been compared with results of previous simulations. It has been shown that there are similar trends between finite element and experimental results.

The Effect of Roundness on the Buckling Strength for the Submerged Pressure Hull

2014 ◽  
Vol 644-650 ◽  
pp. 5133-5137
Author(s):  
Ching Yu Hsu ◽  
Cho Chung Liang ◽  
Tso Liang Teng ◽  
Chia Wei Chang
Keyword(s):  
Underwater Explosion ◽  
Cylinder Pressure ◽  
Pressure Loading ◽  
Finite Element Program ◽  
Buckling Strength ◽  
Element Program ◽  
Analysis Models ◽  
Explosion Load ◽  
Very High ◽  
Design Pressure

The pressure hull is the most important part of resisting pressure structures of the structural systems. The submerged pressure hull is subjected to very high hydrostatic pressure or underwater explosion load, which creates large compressive stress resultants. Due to this the pressure hull is susceptible to buckling. Buckling phenomena analysis is of greater importance in the design of the submerged pressure hulls. For the pressure hulls with local out-of-roundness, the operating depth will be greatly influenced and thus decreasing capability to resist pressure loading. Thus, this work employs the ABAQUS finite element program to analyze the effect of roundness on the buckling strength for the cylinder pressure hull. Sex kinds of out-of-roundness rateφ, 0%, 1%, 3%, 5%, 10% and 15%, were studied in this study. The bulking depth and collapse depth for the cylinder pressure hull with different out-of-roundness rate were calculated. The Analysis models and results of this study contribute to efforts to design pressure hull structures.

scholarly journals Fracture modelling of plain concrete using non-local fracture mechanics and a graph-based computational framework

2021 ◽  
Vol 477 (2252) ◽  
pp. 20210398
Author(s):  
P. Thamburaja ◽  
K. Sarah ◽  
A. Srinivasa ◽  
J. N. Reddy
Keyword(s):  
Finite Element ◽  
Plain Concrete ◽  
Element Analysis ◽  
Computational Framework ◽  
Finite Element Program ◽  
Explicit Finite Element ◽  
Element Program ◽  
Non Local ◽  
Material Length Scale ◽  
Material Length

In this article, we developed a thermodynamically consistent non-local microcracking model for quasi-brittle materials with application to concrete. The model is implemented using a novel graph-based finite element analysis (GraFEA) approach that allows for (i) the probabilistic modeling of the growth and coalescence of microcracks, (ii) the modeling of crack closure using a kinematics-based approach, and (iii) the modeling of rate effects on microcracking. The developed theoretical model and its computational framework is also implemented into the dynamics-based Abaqus/Explicit finite element program through a vectorized user-material subroutine interface. We further demonstrate the procedure for obtaining the parameters (including the non-local intrinsic material length scale, which governs the fracture process) and consequently validate the simulations with independent experimental results.

scholarly journals H-Adaptive Methods for Nonlinear Dynamic Analysis of Shell Structures

1995 ◽  
Vol 2 (3) ◽  
pp. 193-204 ◽  
Author(s):  
Sang-Ho Lee ◽  
Ted Belytschko
Keyword(s):  
Structural Dynamics ◽  
Nonlinear Dynamic Analysis ◽  
Adaptive Methods ◽  
General Purpose ◽  
Shell Structures ◽  
Finite Element Program ◽  
Explicit Finite Element ◽  
Shell Elements ◽  
Element Program ◽  
Projection Techniques

The implementation and application of h-adaptivity in an explicit finite element program for nonlinear structural dynamics is described. Particular emphasis is placed on developing procedures for general purpose structural dynamics programs and efficiently handling adaptivity in shell elements. New projection techniques for error estimation and projecting variables on new meshes after fission or fusion are described. Several problems of severe impact are described.

Experimental and Numerical Study on the Afterburning Effect of TNT

2013 ◽  
Vol 767 ◽  
pp. 46-51
Author(s):  
Wei Cao ◽  
Zhong Qi He ◽  
Wang Hua Chen
Keyword(s):  
Open Space ◽  
Numerical Study ◽  
Detonation Products ◽  
Finite Element Program ◽  
Explicit Finite Element ◽  
Element Program ◽  
Release Model ◽  
Different Gases ◽  
Excessive Oxygen ◽  
Measured Pressure

In order to investigate the afterburning effect of TNT in an open space, a double-layer container (DLC) which can be filled with different gases and enhance the afterburning effect of underoxidized explosives was designed. The charges were located in the inner container, and the outer container was filled with different gases (air, oxygen or nitrogen). The experiments were conducted under water. After initiation, the DLC cracks and provides gas for the detonation products. Underwater static pressure transducer was the main diagnostic. It is shown that pressure and impulse histories for explosions in oxygen and air are greater than those recorded for explosions in nitrogen. Moreover, the afterburning energy was calculated. Results show that the afterburning energy increases with the increase of the amount of oxygen, but cannot reach the theoretically maximum value even though there is excessive oxygen. Finally, two-dimensional numerical simulations were performed by the explicit finite element program ANSYS AUTODYN. The Miller energy release model was used to describe the afterburning process. Results demonstrate that computed pressure histories agreed with measured pressure histories well in terms of initial peak pressure, waveforms and total impulse.

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