Finite Element Simulations and Experimental Investigations of Simple 2-D Geometries in Slamming

2008 ◽  
Author(s):  
Adrian Constantinescu ◽  
Alain Neme ◽  
Nicolas Jacques ◽  
Philippe Rigo
Keyword(s):  
Finite Element ◽  
Water Surface ◽  
Free Water ◽  
Experimental Tests ◽  
Experimental Investigations ◽  
Convergence Criterion ◽  
Numerical Work ◽  
Fluid Structure ◽  
The Impact ◽  
Good Agreement

This paper presents a numerical and experimental study of fluid structure interaction during the impact of a solid body on a water surface. The main request is the modeling of the slamming forces acting on the ship structure in severe sea conditions. The numerical work uses the finite element modeling of a structure impact with free water surface. The first analysis use the commercial finite element code ABAQUS/Standard and combines the assumption of small displacements for the ideal fluid and the solid with an asymptotic formulation for accurate pressure evaluation on the boundary of the wet surface. For deformable strickers, two methods are developed. The first method employs a weak fluid-structure coupling. The second method, more accurate, uses an implicit fluid-structure coupling using a convergence criterion. The second analysis is represented by the simulations of slamming with ABAQUS/Explicit. The simulation uses a viscous, compressible fluid and a soft-exponential law to manage the contact between fluid and solid. The results in term of pressure and total effort applied to the rigid structure are in good agreement with first numerical results and especially with the FLUENT CFD. In order to validate the numerical methods, slamming experimental tests were carried out with a new hydraulic shock press at the ENSIETA laboratory.

Wedge-Shaped Shell Structure Impacting a Water Surface

2005 ◽  
Author(s):  
Adrian Constantinescu ◽  
Volker Bertram ◽  
Ion Fuiorea ◽  
Alain Neme
Keyword(s):  
Water Surface ◽  
Surface Velocity ◽  
Convergence Criterion ◽  
Surface Boundary ◽  
Fluid Structure ◽  
Pressure Fields ◽  
Wet Surface ◽  
Peak Pressures ◽  
The Impact ◽  
Asymptotic Formulation

This paper presents a study of fluid structure interaction during the impact of a ship on a water surface. The analysis combines the assumption of small displacements for the ideal fluid and the solid with an asymptotic formulation for accurate pressure evaluation on the wet surface boundary. A fluid-heat analogy is used to obtain the regular displacement, velocity and pressure fields in the fluid domain with ABAQUS/Standard finite element code. PYTHON and FORTRAN languages are also employed to connect fluid and structure data. Two methods are developed. The first method employs a weak fluid-structure coupling. The average discrepancy between our numerical results and experiments was 22% for the peak pressures for conical shell structures. The wet surface velocity was well predicted. The second method (implicit fluid-structure coupling using a convergence criterion) is more accurate. Recent results with an improved, numerical hydrodynamic model based on CFD are also presented.

Study on Dynamic Characteristics and Parameter Sensitivity of Three Spans Prestressed Continuous Beam

2013 ◽  
Vol 351-352 ◽  
pp. 386-391
Author(s):  
Lu Ning Shi ◽  
Hao Xiang He ◽  
Wei Ming Yan ◽  
Yan Jiang Chen ◽  
Da Zhang
Keyword(s):  
Finite Element ◽  
Natural Frequency ◽  
Frequency Equation ◽  
Dynamic Parameters ◽  
Continuous Beam ◽  
Analytical Expression ◽  
Beam Dynamic ◽  
Frequency Sensitivity ◽  
The Impact ◽  
Good Agreement

Established the three spans prestressed continuous beam dynamic equation, obtained analytical expression of frequency equation. To solve the frequency equation for natural frequency, and compared with the finite element numerical analysis results, the frequency both with analytical expression and with finite element are in good agreement. The formula can be obtained accurately the dynamic parameters of three spans prestressed continuous beam such as frequency. At the same time, the paper also studied the natural frequency sensitivity analysis of three spans prestressed continuous beam, and focuses on the impact on the frequency with effective prestress and prestressed eccentricity.

Explicit Finite Element Study of Liquid Sloshing Behavior in Fluid-Structure Interaction Condition

2017 ◽  
Author(s):  
Shuo Yang ◽  
Raymond K. Yee
Keyword(s):  
Finite Element ◽  
Water Level ◽  
Similarity Theory ◽  
Fluid Structure Interaction ◽  
Water Levels ◽  
Tank Wall ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Sloshing Phenomenon ◽  
The Impact

As a common phenomenon in liquid motions, sloshing usually happens in a partially filled liquid tank of moving vehicle or structure. The objectives of this paper are to study sloshing behavior in rigid tank and deformable tank, and to develop a better performance baffle design in the tank under seismic excitations. The tank is surged with a sinusoidal oscillation about horizontal x-direction. The hydro-elasticity effect of sloshing pressure on the tank wall was taken into consideration due to the fluid-structure interaction between impact pressures and tank structures. ABAQUS finite element program using Coupled Eulerian-Lagrangian (CEL) technique was employed to simulate fluid sloshing. The sloshing phenomenon was studied in rigid tank and deformable tank models with three different water levels, and the effect of wall thickness of the deformable tank on sloshing behavior was discussed. One way to minimize the effect of sloshing in a tank, baffles are used and installed in the middle of the tank, and then various heights and material types of baffle were evaluated. The simulation results show that higher water level case creates greater pressure impact on the tank wall than lower water level case, and the elasticity of the tank structure would reduce the impact pressure of the wall. For the simulation tank model with size of 1m (H) × 1m (W) × 0.2m (D), better performance baffle was found to be the one with the height of 0.35m and was made of acrylic material. Moreover, the conclusion of this study can be extrapolated to other dimensions of the model based on similarity theory. This paper also can serve as an aid in further studying sloshing phenomenon. The findings of this study can be applied to restrain or minimize sloshing motions inside a tank.

Finite-Element Modeling and Model Verification of Steel W-Beam Guardrails Subject to Pendulum Impact Loading

1998 ◽  
Vol 1647 (1) ◽  
pp. 147-157
Author(s):  
T. Russell Gentry ◽  
Lawrence C. Bank
Keyword(s):  
Finite Element ◽  
Impact Loading ◽  
Model Verification ◽  
Federal Highway ◽  
Time Histories ◽  
Tension Capacity ◽  
The Impact ◽  
Impact Events ◽  
Pendulum Impact ◽  
Good Agreement

The experimental and simulated response of steel W-beam guards to pendulum impact loading for impact velocities of 20 km/h, 30 km/h, and 35 km/h are presented. The guardrails were supported by four posts and cable-anchored at each end to ensure that the full tension capacity of the rail could be developed. Experiments carried out with a 912-kg impact pendulum are compared with LS-DYNA finite-element simulations of the impact events. Pendulum tests were completed at the Turner Fairbank Highway Research Center of the Federal Highway Administration. Acceleration, velocity, and displacement time histories are compared for the pendulum impact test and the LS-DYNA simulations. Comparison of the experimental and simulation acceleration records is made using the Numerical Analysis of Roadside Design time-domain statistics. The comparative statistics show that the simulations are in good agreement with the experiments. Guardrail tension data and cable tension data are presented from the LS-DYNA simulations. Results show that the guardrail was close to its tension yield point when impacted an initial velocity of 35 km/h.

scholarly journals 3-D numerical simulation of the tidal circulation in the Gulf of Tonkin, Vietnam

2001 ◽  
Vol 23 (2) ◽  
pp. 116-128
Author(s):  
Phan Ngoc Vinh ◽  
Nguyen Kim Dan
Keyword(s):  
Numerical Simulation ◽  
Water Surface ◽  
Bottom Topography ◽  
Free Water ◽  
System Transformation ◽  
Tidal Circulation ◽  
Turbulence Mixing ◽  
Gulf Of Tonkin ◽  
Quang Ninh ◽  
Good Agreement

The purpose of this paper is to present 3-D numerical simulation of the tidal circulation in the Gulf of Tonkin. A sigma-coordinate system transformation is used to make possible a total fitting between the computing point-grid and the bottom topography as well as the free water surface. A turbulence-closure sub-model K-L which permits the parameterization of the turbulence mixing is also included. The studied domain, the whole Gulf of Tonkin, extends from the coastal zone of Quang-Ninh into Thua Thien Hue province and as far as Hai-Nam (China) island seawards. The model have been calibrated and verified by the observed data at six different stations for a three and seven-day periods. The results are in good agreement with the observed data. The kinetic energy distribution was considered.

scholarly journals Remediation of Nitrogen and Phosphorus from Nursery Runoff during the Spring via Free Water Surface Constructed Wetlands

2010 ◽  
Vol 28 (4) ◽  
pp. 209-217 ◽  
Author(s):  
Sarah A. White ◽  
Milton D. Taylor ◽  
Stewart L. Chandler ◽  
Ted Whitwell ◽  
Stephen J. Klaine
Keyword(s):  
Water Quality ◽  
Water Surface ◽  
Nutrient Loading ◽  
Free Water ◽  
Surface Water Quality ◽  
Phosphorus Loading ◽  
Late Winter ◽  
Nitrogen And Phosphorus ◽  
Free Water Surface ◽  
The Impact

Abstract Agricultural operations face increasing pressure to remediate runoff to reduce deterioration of surface water quality. Some nursery operations use free water surface constructed wetland systems (CWSs) to remediate nutrient-rich runoff. Our objectives were twofold, first to examine the impact of two hydraulic retention times (HRT, 3.5 and 5.5 day) on CWS performance, and second to determine if increased nutrient loading from internal CWS and nursery sources during the spring contributed to nutrient export in excess of regulatory limits. We quantified nutrient loading and removal efficiency in a free water surface CWS from late winter through late spring over three years and monitored various water quality parameters. Total nitrogen in runoff was reduced from 20.6 ± 2.8 mg·liter−1 (ppm) to 4.1 ± 1.3 mg·liter−1 (ppm) nitrogen after CWS treatment. Phosphorus dynamics in the CWS were more variable and unlike nitrogen dynamics were not consistently influenced by water temperature and hydraulic loading rate. Phosphorus concentrations were reduced from 1.7 ± 0.8 mg·liter−1 (ppm) PO4-P in influent to 1.2 ± 0.6 mg·liter−1 (ppm) PO4-P in CWS effluent, but substantial variability existed among years in both phosphorus loading and removal rates. The CWS was able to efficiently remediate nitrogen even under high spring loading rates.

scholarly journals Plastic Deformation of Thin Plates Subjected to Quasi-Static and Dynamic Loadings

2004 ◽  
Vol 1 (1) ◽  
pp. 59 ◽  
Author(s):  
A. A.N. Aljawi
Keyword(s):  
Plastic Deformation ◽  
Finite Element ◽  
Thin Plates ◽  
Circular Plates ◽  
Dynamic Impact ◽  
Deformation And Failure ◽  
Simply Supported ◽  
Dynamic Loadings ◽  
The Impact ◽  
Good Agreement

Deformation and failure of thin plates of mild steel were studied under quasi-static and dynamic impact loadings. Particular emphasis was placed on responses of simply supported circular plates subjected to centric orthogonal loadings. The latter comprised loadings due to relatively massive rigid cylindrical strikers with a hemispherical-end as well as a flat-end. The projectile motions featured variable and low impact velocities. Generally, good agreement was found between experimental results and those predicted by finite-element techniques for displacement-time curves and for force histories of the striker. It was concluded that the ABAQUS-based study (both the implicit and the explicit versions) revealed beneficial insights into the impact mechanics of plates by rigid projectiles. 

Simulations of an Air-Ventilated Strut Crossing Water Surface at Variable Yaw Angles

2018 ◽  
Author(s):  
Konstantin I. Matveev ◽  
Miles P. Wheeler ◽  
Tao Xing
Keyword(s):  
Water Surface ◽  
Free Water ◽  
Suction Side ◽  
Complex Flow ◽  
Air Ventilation ◽  
History Of ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations ◽  
Lift Control ◽  
Good Agreement

Hydrodynamic devices intended to produce lift, control actions, or propulsion can be prone to air ventilation when operating near the free water surface. The atmospheric air may propagate to the low-pressure zones around these devices located under the nominal water level. This often leads to performance degradation of hydrodynamic systems. Modeling of air-ventilated flows is challenging due to complex flow nature and many factors in play. In this study, the computational fluid dynamics simulations are carried out for a surface-piercing strut at different yaw angles. At small yaw angles, the strut underwater surfaces remain wetted, whereas at large yaw and sufficiently high Froude numbers the suction side becomes air ventilated. At the intermediate yaw angles, both wetted and ventilated flow regimes are possible, and the existence of a specific state depends on the history of the process. The present computational results demonstrate good agreement with available experimental data.

Novel U-bending designed setups for investigating the spring-back/spring-go of two-layer aluminum/copper sheets through experimental tests and finite element simulations

2020 ◽  
Vol 234 (8) ◽  
pp. 1142-1153 ◽  
Author(s):  
Ehsan Etemadi ◽  
Abbas Naseri ◽  
Mohsen Valinezhad
Keyword(s):  
Finite Element ◽  
Experimental Tests ◽  
Finite Element Simulations ◽  
Curvature Radius ◽  
Stacking Sequence ◽  
Spring Back ◽  
Effective Parameters ◽  
Bending Process ◽  
Copper Aluminum ◽  
Good Agreement

This paper presents novel U-bending setups in order to investigate the effects of the curvatures created on the punch, die, or both on the spring-back/spring-go of the two-layer aluminum/copper sheets. Comparison of the new U-bending setups with the regular ones showed that the curvatures had important roles in reducing the spring-back/spring-go in the U-bending process. The results further indicated the good agreement between spring-back/spring-go and finite element simulations. Moreover, through finite element simulations, the effects of three effective parameters on reducing the spring-back/spring-go, including the curvature radius ( r) of the punch, the distance between curvature center and the fillet center ( d) in the punch, and the curvature radius at the end of the die ( R) were investigated. In achieving the desired state (90°), the results showed that the distance of curvature center from the fillet center ( d) was a more important parameter compared with the curvature radius at the end of the punch ( r) and the curvature radius at the end of the die ( R). This paper also focuses on the thicknesses of copper and aluminum as well as the stacking sequence of layers. Concerning the thicknesses of the implemented copper and aluminum change, the minimum angle of the spring-back/spring-go relative to the desired state was 75% Al/25% Cu thickness. Furthermore, the spring-back of aluminum/copper was lower than the copper/aluminum layer sheet. The effects of both thickness changing and stacking sequence of aluminum/copper layers on the spring-back/spring-go amounts of different sheets were due to the relocation of the neutral axis.

Finite Element Approximation of Fluid Structure Interaction (FSI) Optimization in Arbitrary Lagrangian-Eulerian Coordinates

2013 ◽  
Author(s):  
Bhuiyan Shameem Mahmood Ebna Hai ◽  
Markus Bause
Keyword(s):  
Finite Element ◽  
Fluid Structure Interaction ◽  
Arbitrary Lagrangian Eulerian ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Finite Element Software ◽  
Special Cases ◽  
Non Linear ◽  
Non Linear System ◽  
The Impact

Advanced composite materials such as Carbon Fiber Reinforced Plastics (CFRP) are being applied to many aircraft structures in order to improve performance and reduce weight. Most composites have strong, stiff fibers in a matrix which is weaker and less stiff. However, aircraft wings can break due to Fluid-Structure Interaction (FSI) oscillations or material fatigue. This paper focuses on the analysis of a non-linear fluid-structure interaction problem and its solution in the finite element software package DOpElib: the deal.II based optimization library. The principal aim of this research is to explore and understand the behaviour of the fluid-structure interaction during the impact of a deformable material (e.g. an aircraft wing) on air. Here we briefly describe the analysis of incompressible Navier-Stokes and Elastodynamic equations in the arbitrary Lagrangian-Eulerian (ALE) frameworks in order to numerically simulate the FSI effect on a double wedge airfoil. Since analytical solutions are only available in special cases, the equation needs to be solved by numerical methods. This coupled problem is defined in a monolithic framework and fractional-step-θ time stepping scheme are implemented. Spatial discretization is based on a Galerkin finite element scheme. The non-linear system is solved by a Newton method. The implementation using the software library package DOpElib and deal.II serves for the computation of different fluid-structure configurations.

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