ASYMMETRICAL WATER IMPACT OF TWO-DIMENSIONAL WEDGES WITH ROLL ANGLE WITH MULTI-MATERIAL EULERIAN FORMULATION

2021 ◽  
Vol 156 (A2) ◽  
Author(s):  
S Wang ◽  
C Guedes Soares
Keyword(s):  
Impact Force ◽  
Water Entry ◽  
Roll Angle ◽  
Two Dimensional ◽  
Water Impact ◽  
Explicit Finite Element ◽  
Eulerian Formulation ◽  
Calm Water ◽  
Hydrodynamic Study ◽  
Total Impact

A hydrodynamic study on the asymmetrical water impact of two-dimensional wedges with roll angle is presented. The slam induced loads on the wedges entering calm water with both vertical and horizontal velocities are predicted based on the explicit finite element method. The effects of the horizontal impact velocity and the roll angle are investigated through the predicted results of pressure distribution, pressure variation during the water entry and total impact force, which are also compared with analytical formulations and other numerical calculations. The present method gives reasonable predictions, compared to the numerical and analytical results.

Asymmetrical Water Impact of Two-Dimensional Wedges with Roll Angle with Multi-material Eulerian Formulation

2014 ◽  
Vol 156 (A2) ◽  
Keyword(s):  
Impact Force ◽  
Water Entry ◽  
Roll Angle ◽  
Two Dimensional ◽  
Water Impact ◽  
Explicit Finite Element ◽  
Eulerian Formulation ◽  
Calm Water ◽  
Hydrodynamic Study ◽  
Total Impact

A hydrodynamic study on the asymmetrical water impact of two-dimensional wedges with roll angle is presented. The slam induced loads on the wedges entering calm water with both vertical and horizontal velocities are predicted based on the explicit finite element method. The effects of the horizontal impact velocity and the roll angle are investigated through the predicted results of pressure distribution, pressure variation during the water entry and total impact force, which are also compared with analytical formulations and other numerical calculations. The present method gives reasonable predictions, compared to the numerical and analytical results.

ANALYTICAL SOLUTION OF WEDGE WATER ENTRY BY USING SCHWARTZ–CHRISTOFFEL CONFORMAL MAPPING

2011 ◽  
Vol 02 (03) ◽  
pp. 337-354 ◽  
Author(s):  
PARVIZ GHADIMI ◽  
AMIR SAADATKHAH ◽  
ABBAS DASHTIMANESH
Keyword(s):  
Conformal Mapping ◽  
Impact Force ◽  
Offshore Structures ◽  
Water Entry ◽  
The Body ◽  
Water Impact ◽  
Local Pressure ◽  
Maximum Impact Force ◽  
The Impact ◽  
First Time

Water impact is one of the most critical phenomena from the viewpoint of the structural design of ships and offshore structures. The impact force can impose a large load with high local pressure on the body surface. On the other hand, determination of the maximum impact force during impact and acting point itself is very important in the design of floats. In this paper, the water entry of a two-dimensional wedge section is considered. This study is carried out in the framework of a potential-flow assumption. In particular, water impact on a dropping wedge with a constant velocity is pursued analytically by using the Schwartz–Christoffel conformal mapping. In order to determine a position of the wedge where the instantaneous effective force is largest during the impact, a particular equation is introduced here for the first time. The pressure distribution and maximum impact force are also calculated. The obtained results are compared against other numerical and experimental works and favorable agreement is displayed.

Slamming Loads on a Wedge Elastically Suspended on a Marine Structure

2015 ◽  
Author(s):  
Hui Sun ◽  
Jens B. Helmers
Keyword(s):  
Free Surface ◽  
Impact Force ◽  
Water Entry ◽  
The Body ◽  
Water Impact ◽  
Surface Conditions ◽  
Marine Structure ◽  
Nonlinear Free Surface ◽  
Stiffness And Damping ◽  
Water Exit

Slamming loads on a two-dimensional wedge elastically suspended on a marine structure are analyzed by using either a combined Wagner and von Karman method (W-vK) or a boundary element method (BEM). Fully nonlinear free surface conditions are satisfied in the BEM. Hydroelasticity effects are considered in both methods. A sinusoidal free surface motion relative to the marine structure is specified for the slamming event. Both the water entry phase and the water exit phase are simulated. The numerical results by the two different methods are compared. The W-vK method can generally predict the same trend of the variation of the body motions and the water forces, although the predicted maximum forces are larger than those by the BEM. The influence of the stiffness and damping of the elastic connection on the water impact force are discussed.

Water Impact Analysis for Aircraft over Sea

2013 ◽  
Vol 341-342 ◽  
pp. 563-566
Author(s):  
Man Yao
Keyword(s):  
Pitch Angle ◽  
Impact Analysis ◽  
Impact Force ◽  
Contact Condition ◽  
Flying Height ◽  
Force Model ◽  
Two Dimensional ◽  
Water Impact ◽  
Water Contact ◽  
Trajectory Angle

The modern aircrafts flying height is strictly limited by the conditions on the sea. Terrible conditions may lead overturning or dropping into the water to the aircraft. Whats more, the structure of the aircraft may be broken by water-impact force. The affection of the water impact must be considered to promise the safety of the aircraft. This paper focuses on the water impact to a typical symmetrical aircraft flying above sea. The water impact force related to the trajectory angle and equivalent pitch angle is researched based on the water impact force model of a two-dimensional wedge. In addition, concerning with the limitation of the aircrafts overload, the water-contact condition is proposed to avert attitude overturning and structure broken of the aircraft.

Impact on an Ice Floe With a Surface Crack

2018 ◽  
Author(s):  
Alexander A. Korobkin ◽  
Tatiana I. Khabakhpasheva
Keyword(s):  
Impact Force ◽  
Lower Surface ◽  
Time Instant ◽  
Constant Thickness ◽  
Two Dimensional ◽  
Water Impact ◽  
Impulsive Load ◽  
Torsional Spring ◽  
Impact Theory ◽  
The Impact

A floating two-dimensional ice plate with a crack on its lower surface is considered. Deflection of the plate is caused by an external impulsive load. The ice floe dynamics is described by thin compound elastic plate equation. Two parts of the plate are of constant thickness and are connected by a torsional spring which models the crack effect on the elastic deflection of the plate. The stiffness of the equivalent torsional spring is given as a function of the plate parameters and the crack length. Both the motions of the ice plate and the stresses near the crack tip are determined without account for gravity and surface tension effects. In the symmetric problem, the crack is always perpendicular to the plate surface. The growth of the crack is governed by the condition of the crack equilibrium at each time instant. The conditions of the impact, the magnitude of the impact force and its duration, which lead to the crack growth are studied within the water impact theory.

The Study on Crashworthiness Performance of Thin-Walled Structures and the Effect of Welding Performance on it

2011 ◽  
Vol 63-64 ◽  
pp. 655-658
Author(s):  
Qi Hao ◽  
Sheng Jun Wu
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Welded Joints ◽  
Impact Force ◽  
Deformation Energy ◽  
Optimal Shape ◽  
Explicit Finite Element Method ◽  
Explicit Finite Element ◽  
Thin Walled Structures ◽  
Thin Walled

Explicit finite element method is adopted to simulate the crashworthiness performance of four types of typical thin—walled structures used in vehicle by software LS-DYNA. The structures with the same material、area and length are crash by a rigid body with 40km/h in10ms, The crash processes and crashworthiness characters are analyzed by a series crash parameters: deformation energy with unit displacement, impact force and deceleration to look for the optimal shape with crashworthiness. With comparing, the double caps section has ascendant performance than the others. The simulating methods of welded-joints are discussed to analysis their effects on crashworthiness simulation.

scholarly journals Impact Force of Free-fall Lifeboats at Water Entry

1994 ◽  
Vol 90 (0) ◽  
pp. 165-173
Author(s):  
Kazuo HITOMI ◽  
Osamu MIYATA
Keyword(s):  
Impact Force ◽  
Free Fall ◽  
Water Entry

On the Cushioning of Water Impact by Entrapped Air

1968 ◽  
Vol 12 (02) ◽  
pp. 116-130 ◽  
Author(s):  
Grant Lewison ◽  
W. M. Maclean
Keyword(s):  
Free Surface ◽  
Flat Plate ◽  
Water Surface ◽  
Peak Pressure ◽  
Water Movement ◽  
Theoretical Work ◽  
Two Dimensional ◽  
Water Impact ◽  
Entrapped Air

Impact between a rigid flat plate and the free surface of water has been investigated experimentally and theoretically. Under two-dimensional conditions, the experiments give values of peak pressure of the same order as those recorded on ships slamming at sea, but very much smaller than would be expected from existing theories. New theoretical work is presented which takes account of the air trapped between the model and the water surface, and of both compressible and incompressible water movement. This shows good general agreement with the experiments, though further work is needed to confirm some of the assumptions made.

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