• Journal of Navigation and Port Research
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• v.39 no.1
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• pp.77-82
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• 2015

Slamming means that the hull hits the waves and receives impact pressure. This slamming effect may cause harm to people and when you put the hull at risk. so it is very harmful for cargo safety. Therefor slamming impact pressure should be fully considered in ship designing. In this study the model of wedged type structure are produced aimed to simulate a free fall that the experiments were carried out on different weight and free fall height. The flow field has been obtained by 2-frame grey level cross correlation PIV(Particle Image Velocimetry) method and experiment was divided into water entry and water exit. The impact pressure of free fall structure by a pressure acquisition system apply to dewetron system. The angles between a model and the water surface are adapted $15^{\circ}$ respectively. The weight change of models was given as 1.5, 1.8 and 2.0kg. To study slamming phenomenon for free fall height the experiments were carried out by the free fall height of 100, 200 and 300mm. The experimental value of the impact pressure according to the changes in weight was increase impact pressure in proportion to the increase in weight and higher free falling height has also influenced the increase in impact pressures.

• Journal of the Korean Society of Marine Environment & Safety
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• v.18 no.4
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• pp.371-377
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• 2012

This paper presents an experimental investigation to figure out slamming impact pressure and flow characteristics of a rectangular Marine structure($800{\times}250{\times}50mm^3$) in free fall. The flow field has been obtained by 2-frame grey level cross correlation PIV(Particle Image Velocimetry) method, the impact pressure of the free fall model by a pressure acquisition system(Dewatron). The angles between a model and the free surface are adapted $10^{\circ}$ and $20^{\circ}$ respectively. Velocity field of water exit has higher better than water entry. The highest point, P2 of impact pressure under the bottom of the model has been appeared about 6 % higher values at 20 degrees than 10 degrees.

• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.2
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• pp.213-218
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• 2013

This paper presents are experimental investigation to figure out slamming impact pressure and flow characteristics of a wedge type structure in free fall. The flow field has been obtained by 2-frame grey level cross correlation PIV(Particle Image Velocimetry) method, the impact presure of free fall structure by a pressure acquisition system apply to Dewetron system. The angles between a model and the free surface are adapted $15^{\circ}$, $25^{\circ}$, $35^{\circ}$ and $45^{\circ}$ respectively. Velocity field of water exit has higher better than water entry. The impact pressure under the bottom of the model ha been appeared higher values at 15 degrees than 45 degrees, and also at P1.

• Journal of Ocean Engineering and Technology
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• v.21 no.1 s.74
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• pp.40-44
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• 2007

This paper presents the experimental results on slamming phenomenon. The air pressure cylinder was used to ensure repeatability of the impact. The results showed that the adopted experimental technique was excellent in terms of repeatability, compared to that of the free drop tests. The pressure time histories, magnitude of peak pressure and the behavior of jetspray were obtained. The flat specimen was tested for various incident angles. To estimate the incident speed of the specimen, a high-speed camera was used. The high-speed camera was also a useful tool in understanding the behavior.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.392-395
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• 2006

This paper presents the experimental results at slamming phenomenon. The air pressure cylinder was used to ensure repeatability of the impact. The results showed that the adopted experimental technique was very excellent in terms of repeatability when is compared to that of the free drop tests. The pressure time histories, magnitude of peak pressure and the behavior of jet spray were obtained. The flat specimen was tested for various incident angles. To estimate the incident speed of the specimen high speed camera was used. The high speed camera was also useful tool in understanding the behavior.

• Journal of the Society of Naval Architects of Korea
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• v.55 no.3
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• pp.187-195
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• 2018

Ship's bottom slamming has been studied by many researchers for a very long time. But still some ships suffer structure damages caused by the bottom slamming impacts. This paper presents a practical computation method of the design impact pressure due to ship's bow bottom slamming. Large heave and pitch motions of a rigid hull ship are simulated by the nonlinear strip method in time domain and the relative colliding velocity between the bow bottom and the water surface is calculated using the simulated ship motions. The bottom slamming impact pressure is calculated as a product of the relative colliding velocity squared and the bottom slamming pressure coefficient that is obtained by modification of the SNAME pressure coefficients based on Ochi's slamming experiments. Not only the bottom slamming pressures but also the required bottom plate thicknesses are calculated and compared with those of the classification society rules. The comparisons show good agreements and it is confirmed that the present method is practically very useful for the bottom structure design against ship's bow bottom slamming impacts.

• Journal of Ocean Engineering and Technology
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• v.31 no.1
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• pp.22-27
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• 2017

This paper presents the results of an experimental study on the wedge slamming impact problem, including the fluid-structure interaction. A free drop test was performed to estimate the hydroelasticity. Three wedges were fabricated of 5 mm thick steel plate. The deadrise angles were $15^{\circ}$, $20^{\circ}$, and $25^{\circ}$. Plate thicknesses of 2 mm and 3 mm were used to determine the effect of the structural rigidity. The drop heights were 25 cm, 50 cm, 75 cm, and 100 cm. The pressure on a rigid part of the wedge and strain of the elastic plate were measured at four different locations. The pressure was compared using the Wagner theory and generalized Wagner theory.

• Journal of Ocean Engineering and Technology
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• v.29 no.2
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• pp.163-168
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• 2015

This paper presents the results of experimental work on the wedge slamming impact problem. An experiment was done with a wedge model. The deadrise angle of the wedge was $4^{\circ}$. The model was made in two parts: the outside part was made of a 5-mm-thick steel plate that could be assumed to be a rigid body, and the inside part was made of a thin SUS plate that could be assumed to be an elastic body. Thin SUS plate thicknesses of 2 mm and 3 mm were used to determine the effect of plate rigidity. The drop height was varied from 0.25 m to 1 m to determine the effect of a large deformation.

• Journal of the Society of Naval Architects of Korea
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• v.36 no.2
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• pp.77-93
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• 1999

The twin aims of the paper are to investigate the collapse strength characteristics of ship plating subject to impact pressure loads and to develop a simple structural design formula considering impact load effects. The general purpose nonlinear finite element program STARDYNE together with existing experimental results is used to investigate the collapse behavior of plating under impact pressure loads. The rigid plastic theory taking into account large deflection effects is applied to the development of the design formulation. In the theoretical method, the collapse strength formulation for plating subject to hydrostatic pressure is first derived using the rigid plastic theory. By including the strain rate erects in the formulation it can be applied to impact pressure problems. As illustrative examples, the collapse behavior of steel unstiffened plates and aluminum alloy stiffened panels subject to impact pressure loads is analyzed.

• Journal of Ocean Engineering and Technology
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• v.23 no.1
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• pp.60-66
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• 2009

This study presents an experimental investigation of the shallow water impact of a box type structure. The analysis was done based on the video images captured by a high speed camera, the flow field obtained by PIV (Particle Image Velocimetry), and pressure measurements in the divided region. The video images showed quite good agreement with the description given by Korobkin. The PIV measurements of the velocity field provided a clear view of the flow pattern for all three stages. The pressure was measured at the bottom of the tank with strain gauge type pressure gauges. The pressure measurements showed the characteristics of divided regions.