Comparative Study of Hydroelastic Impact for One Free-Drop Wedge With Stiffened Panels by Experimental and Explicit Finite Element Methods

2011 ◽  
Author(s):  
Hanbing Luo ◽  
Hui Wang ◽  
C. Guedes Soares
Keyword(s):  
Finite Element ◽  
Stress Responses ◽  
Complex Structure ◽  
Water Entry ◽  
Explicit Finite Element ◽  
Stiffened Panels ◽  
Longitudinal Stiffeners ◽  
Free Drop ◽  
Good Agreement ◽  
Impact Problem

This paper studies the hydroelastic responses of a complex structure for one water entry problem. One steel wedge with complex stiffened panels was designed with a deadrise angle of 22 degrees and a series free-drop model tests were carried out. An explicit finite element code is adopted to simulate this coupled hydroelastic impact problem. The motion, stress responses on longitudinal stiffeners and transverse frames are obtained. Comparisons of the numerical and the experimental results are carried out. Good agreement is achieved. The hydroelastic effect is discussed.

On the Ductile Response of Stiffened Panels Subjected to Lateral Indentation: Experimental and Numerical Analysis

2010 ◽  
Author(s):  
Hagbart S. Alsos ◽  
Jo̸rgen Amdahl
Keyword(s):  
Finite Element ◽  
Plate Thickness ◽  
Offshore Structures ◽  
Instability Criterion ◽  
Potential Hazard ◽  
Explicit Finite Element ◽  
Stiffened Panels ◽  
Environmental Consequences ◽  
Structural Capacity ◽  
Indentation Tests

Reliable prediction of ductile fracture is essential in analysis of accidental response of ships and offshore structures. The consequences of fracture are significant. It may imply a significant reduction in structural capacity. It may also pose a potential hazard for human safety, as well as lead to an environmental and economical loss, e.g. caused by tanker collision or grounding. A series of five steel-plate indentation tests were conducted at the Norwegian University of Science and Technology (NTNU), Department of Mariner Technology, during late fall 2007. These are performed quasi-statically on various configurations of stiffened panels. The tests represent hull or deck plates in ships or platform structures subjected to accidental actions from ship-ship collisions, ship grounding or dropped object impacts. Various configurations of stiffened panels are tested, all laterally by a cone shaped indenter until fracture occurred. The specimen dimensions represent a 1:3 scale of the dimensions found in medium sized tankers, i.e. plate thickness of 5 mm. Naturally, because damaged hull and cargo tanks may cause severe environmental consequences, focus is on the plastic deformation and fracture resistance of the panels. The panel tests are primarily intended to serve as verification for advanced finite element simulations using a failure criterion based on instability mechanisms, i.e. local necking. This is implemented into the non linear explicit finite element code LS-DYNA and is referred to as the BWH instability criterion. In addition, the influence of the element size with respect to onset of failure is studied using three different element sizes for the various test cases. Although, attention is primarily placed on accidental scenarios, such as ship collision and grounding, the experimental results are of considerable relevance for other types of abnormal actions, e.g. dropped objects on deck and subsea structures, and stiffened panels subjected to explosion or ice actions.

Response of UHPC-Concrete Composite Structural Members Using Implicit and Explicit Finite Element Method

2019 ◽  
Vol 793 ◽  
pp. 93-97 ◽  
Author(s):  
Hor Yin ◽  
Kazutaka Shirai ◽  
Wee Teo
Keyword(s):  
Finite Element ◽  
Fe Simulation ◽  
Fe Analysis ◽  
Experimental Results ◽  
Structural Members ◽  
Explicit Finite Element ◽  
Explicit Analysis ◽  
Cracking Pattern ◽  
Implicit And Explicit ◽  
Good Agreement

This paper investigates the response of UHPC-concrete composite structural members using implicit and explicit finite element (FE) methods. Both methods were prepared and conducted individually for the FE analysis under static loading condition. Results of the implicit and explicit analysis were compared to experimental results conducted in previous study. Both the implicit and explicit methods showed similar overall response with fair accuracy compared with the experimental results. In addition, the effective plastic strain obtained from the FE simulation was in good agreement with the damage cracking pattern in the experiment.

scholarly journals Ship Loading Influence on the Slamming Impact of Typical Sections of an S-175 Container Ship

2020 ◽  
Vol 8 (3) ◽  
pp. 163
Author(s):  
Guanghua He ◽  
Binyang Xie ◽  
Wei Wang ◽  
Shuang Liu ◽  
Penglin Jing
Keyword(s):  
Loading Condition ◽  
Early Stage ◽  
Water Entry ◽  
Container Ship ◽  
Arbitrary Lagrangian Eulerian ◽  
Explicit Finite Element ◽  
Loading Effects ◽  
Sectional Shape ◽  
Wave Induced ◽  
Good Agreement

This paper investigates the influence of ship-loading condition on slamming during water entry. Three typical sections of the S-175 container ship, namely the bow, parallel middle body and stern, under three different loading conditions are studied. Full-sized models are established and simulated by commercial software LS-DYNA based on the explicit finite element method (FEM) using the arbitrary Lagrangian–Eulerian (ALE) algorithm. At first, validation is carried out by simulating the Wave Induced Loads on Ships Joint Industry Project II (WILS JIP-II) ship section entering the water and by verifying that the response is in good agreement with published experimental data. Then, nine different cases with three typical sections of the container ship and three different loadings, including the no-load (lightship weight), half-load and full-load weights of the ship, are investigated. Finally, the influence of the ship loading and sectional shape on the water impacts is analyzed and discussed. The present study is useful for the analysis of loading effects on ship slamming at the early stage of ship design.

Numerical Simulation of Blast Loadings on a Thick-Walled Cylindrical Vessel

2007 ◽  
Author(s):  
Guide Deng ◽  
Ping Xu ◽  
Jinyang Zheng ◽  
Yongjun Chen ◽  
Yongle Hu ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Dynamic Response ◽  
Rigid Wall ◽  
Cylindrical Vessel ◽  
Finite Element Code ◽  
Explicit Finite Element ◽  
Shell Deformation ◽  
Blast Loadings ◽  
Good Agreement

Determining blast loadings on an explosion containment vessel (ECV) is the foundation to design the ECV. Explosion of TNT centrally located in a thick-walled cylindrical vessel and its impact on the cylinder was simulated using the explicit finite element code LS-DYNA. Blast loadings on the cylinder computed are in good agreement with the corresponding experimental results. Then wall thickness and yield stress of the cylinder were changed in the following simulation to investigate effect of shell deformation on blast loadings. It is revealed that shell deformation during the primary pulses of blast loadings is so slight that it has little influence on the blast loadings. Though the deformation may increase greatly after the primary pulses, the dynamic response of an ECV is mainly affected by the primary pulses. Therefore, decoupled analyses are appropriate, in which the shell of an ECV is treated as a rigid wall when determining blast loadings on it.

scholarly journals A plane-stress plasticity model for masonry for the explicit finite element time integration scheme

2020 ◽  
Vol 53 (3) ◽  
pp. 240-258
Author(s):  
Oliver Gustav Sebastian Lundqvist ◽  
Michael Chauhan
Keyword(s):  
Finite Element ◽  
Biaxial Loading ◽  
Time Integration ◽  
Material Model ◽  
Integration Scheme ◽  
Plasticity Model ◽  
Explicit Finite Element ◽  
Time Integration Scheme ◽  
Uniaxial And Biaxial Loading ◽  
Good Agreement

Masonry is a composite material and can be considered anisotropic on a macroscopic scale, i.e., masonry exhibits different properties in different directions, both in the elastic and inelastic range. Like other quasi-brittle materials, masonry exhibits softening and hardening behavior after failure for compression and tension. In this paper a smeared continuum plasticity model of masonry is presented as well as it numerical implementation in an explicit finite element time integration scheme, as such a material model does not exist for a commercial explicit finite element solver. The implementation is done by writing a user-defined material model (VUMAT) as a Fortran subroutine in the commercial software ABAQUS Explicit. The material model is tested both in uniaxial and biaxial loading against similar tests from earlier research. The results show good agreement with earlier research.

scholarly journals A Technique for Dynamic Analyses of Containers With Locking-Ring Closures

2002 ◽  
Author(s):  
Tsu-te Wu
Keyword(s):  
Finite Element ◽  
Dynamic Analysis ◽  
Complex Structure ◽  
Ring Closure ◽  
Dynamic Responses ◽  
Explicit Method ◽  
Element Analysis ◽  
Explicit Finite Element ◽  
The Finite Element Analysis ◽  
Dynamic Analyses

The explicit method of the finite-element analysis is capable of analyzing the dynamic responses of a complex structure with complicated contact conditions. The method has been widely used in evaluating the dynamic responses of shipping package for radioactive materials. However, the previous analyses focused on the stresses and deformations of the structure components subjected impact loads and the possibility of the locking-ring closure separating from the drum body is not accounted for. The major difficulty for applying the explicit method to a container with a locking-ring closure is that the phenomenon of pre-loading a locking-ring closure is a static process; whereas, the explicit method involves the propagation of stress waves in the structure and thus is only applicable to dynamic analyses. The purpose of the present paper is to propose a technique that extends the application of the explicit finite-element method to the dynamic analysis of the container pre-loaded by a lock-ring. Unlike the conventional dynamic analysis by the explicit method that only needs one load step, the proposed technique requires three sequential procedure steps (not load steps) to complete an entire analysis. Furthermore, one procedure step may consist of two load steps. The paper discusses the procedures of the proposed technique in details. The application of the technique is illustrated by an example problem. The adequacy of the technique is also verified.

Optimization for Motorcycle Tire Using Explicit FEM

2001 ◽  
Vol 29 (4) ◽  
pp. 230-243 ◽  
Author(s):  
M. Koide ◽  
H. Heguri ◽  
T. Kamegawa ◽  
Y. Nakajima ◽  
H. Ogawa
Keyword(s):  
Neural Network ◽  
Finite Element ◽  
Design Space ◽  
Objective Functions ◽  
Explicit Finite Element ◽  
Handling Performance ◽  
The Neural Network ◽  
Practical Development ◽  
Contour Design ◽  
Good Agreement

Abstract A new procedure of the crown contour design for the motorcycle tire is proposed in this paper. The explicit finite element method (FEM) combined with the neural network has been utilized to optimize the cornering property of the motorcycle tire. For the motorcycle tire, the camber thrust is one of the most important cornering characteristics. The explicit FEM has been utilized for the camber thrust prediction to avoid poor numerical stability that will be caused by the implicit FEM. The prediction of the camber thrust that the results of finite element analyses (FEA) were in good agreement with the experimental results has been verified. For the approximation of the design space in the optimization, the neural network has been utilized to circumvent the multipeak and huge CPU time problems. The objective functions of the optimization were both the linearity of camber thrust and the uniformity of pressure distribution in the contact area. The design variable was the crown contour expressed by three variables, and the number of variables was defined in consideration of decreasing the number of FEA. The procedure has been applied to the practical development of a motorcycle tire and verified to be an effective method to improve the handling performance at the proving ground.

Numerical Simulation of Hydroelastic Responses of Flat Stiffened Panels Under Slamming Loads

2010 ◽  
Author(s):  
Hanbing Luo ◽  
Jiajun Hu ◽  
C. Guedes Soares
Keyword(s):  
Numerical Simulation ◽  
Water Entry ◽  
Pressure Response ◽  
Flexible Bodies ◽  
Explicit Finite Element ◽  
Stiffened Panels ◽  
Panel Stiffness ◽  
Air Cushion ◽  
Hydroelastic Response

Explicit finite element code is adopted to simulate the dynamic response of flat stiffened panels under slamming loads. In order to validate the code, numerical simulation of pressure response is carried out and compared with experimental results published. One panel with ‘T’ stiffeners is proposed for water entry problem with 0° dead rise angle. Both rigid and flexible bodies are investigated. Pressure response on coupling surface is predicted and compared with each other. Hydroelastic response of stiffened panels is studied in details, with focus on stress response in panel and stiffener. Coupling effects between fluid and structures are discussed. Sensitivity analysis is carried out. Factors influencing the role of hydroelasticity are discussed, such as air cushion effects, impact velocity, and panel stiffness, etc.

Dynamic Explicit Finite Element Code for U-Bending Simulation and Springback Prediction

2014 ◽  
Vol 660 ◽  
pp. 337-341 ◽  
Author(s):  
Agus Dwi Anggono ◽  
Tri Widodo Besar Riyadi ◽  
Waluyo Adi Siswanto
Keyword(s):  
Finite Element ◽  
Free Software ◽  
Finite Element Code ◽  
Explicit Method ◽  
Element Analysis ◽  
Explicit Finite Element ◽  
Simulation Process ◽  
Experimental Works ◽  
Springback Prediction ◽  
Good Agreement

In this paper, a dynamic explicit method was used to simulate U-bending processes of aluminium and its springback. The simulation was carried out using a free software of finite element analysis code namely Impact. The model was taken from a benchmark model in Numisheet'93. The numerical results of the dynamic explicit code were compared with the results of the experimental works. After the optimization was done using the simulation process, it was found that the springback results showed a good agreement with that done by the experimental results. The software Impact was capable of simulating the U-bending processes and predicting the occurrence of springback.

scholarly journals Numerical and Experimental Investigation of Aircraft Panel Deformations During Riveting Process

2015 ◽  
Vol 137 (1) ◽  
Author(s):  
Gasser F. Abdelal ◽  
Georgia Georgiou ◽  
Jonathan Cooper ◽  
Antony Robotham ◽  
Andrew Levers ◽  
...  
Keyword(s):  
Finite Element ◽  
Element Model ◽  
Static Stress ◽  
Finite Element Models ◽  
Explicit Finite Element ◽  
Manufacturing Process Control ◽  
Longitudinal Stiffeners ◽  
Riveting Process ◽  
Dimensional Growth ◽  
Aircraft Panels

In collaboration with Airbus-UK, the dimensional growth of aircraft panels while being riveted with stiffeners is investigated. Small panels are used in this investigation. The stiffeners have been fastened to the panels with rivets and it has been observed that during this operation the panels expand in the longitudinal and transverse directions. It has been observed that the growth is variable and the challenge is to control the riveting process to minimize this variability. In this investigation, the assembly of the small panels and longitudinal stiffeners has been simulated using static stress and nonlinear explicit finite element models. The models have been validated against a limited set of experimental measurements; it was found that more accurate predictions of the riveting process are achieved using explicit finite element models. Yet, the static stress finite element model is more time efficient, and more practical to simulate hundreds of rivets and the stochastic nature of the process. Furthermore, through a series of numerical simulations and probabilistic analyses, the manufacturing process control parameters that influence panel growth have been identified. Alternative fastening approaches were examined and it was found that dimensional growth can be controlled by changing the design of the dies used for forming the rivets.

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