Wyniki wyszukiwania - BazTech

1

Residual Ultimate Strength of Box Girders with Variable Cracks

Ao L., Wang D.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

|

2015

|

Vol. 9, no. 2

193--198

EN

The aim of the present study is to investigate the residual ultimate strength characteristics of box girders with variable cracks under torsional loading. A series of finite element models are established by changing the crack length and crack angle using a commercial FEA program, ABAQUS. The cracks are located at the center and torques are applied on both ends of the box beam. Different aspect ratios are considered to evaluate the effects of cracks on box beams for various widths and lengths of panels in the middle yielding region. The accuracy of the nonlinear FEA results is veri?ed by a comparison with previous predicted formulas. Based on the FEA results, the relationship between the residual ultimate strength and crack parameters can be indicated in a function with period of in the form of Fourier series.

2

Experimental Study of Forces Exerted on Ships Due to the Vertical Walls of Navigation Channels

Fathi-Kazerooni M., Seif M. S.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

|

2015

|

Vol. 9, no. 2

199--203

EN

Ship maneuvering in restricted waters of harbor basins and navigation channels had been the main concern in recent years due to sudden increase of ship’s size. When the ship enters a navigation channel the lateral boundary of the channel exerts a transverse force and turning moment on the ship hull. These forces are so important in the analysis of safety of ship navigation in the channels. Ship model test in the towing tank is a reliable method to evaluate these forces. Therefore systematic model tests are held for modeling of the forces exerted on the tanker ship and dhow model traveling alongside a vertical wall. A database of the interaction forces is developed and the specific hydrodynamic effects related to the phenomena are discussed. The results can be used for simulation of ship maneuvering and assessment of safety limits for navigation of ships alongside the quay walls and breakwaters.

3

Trim Optimisation - Theory and Practice

Reichel M., Minchev A., Larsen N. L.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

|

2014

|

Vol. 8, no. 3

387--392

EN

Force Technology has been working intensively with trim optimisation tests for almost last 10 years. Focus has primarily been put on the possible power savings and exhaust gases reduction. This paper describes the trim optimisation process for a large cargo vessel. The physics behind changed propulsive power is described and the analyses in order to elaborate the optimum trimmed conditions are presented. Different methods for prediction of required power in trimmed conditions are presented and results are compared against each other. The methods with their advantages and disadvantages are discussed. On the basis of power prediction, a trim guidance with dedicated SeaTrim® software for ship master is made and presented.

4

The Need of the Revision of Passenger Ships’ Stability Criterion on Account of Turning

Szozda Z.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

|

2014

|

Vol. 8, no. 3

393--399

EN

The angle of heel on account of turning is one of the mandatory stability criteria for passenger ships. Formula used for calculations of this criterion contained in the International Code on Intact Stability [13] is criticized at present. Agendas of the Sub-committee on Ship Design and Construction (SDC) for the first (2014) and the second (2015) sessions contain the item on revision of this criterion and corresponding regulation. The paper presents some shortcomings of the criterion. Turning tests of a freely maneuvering model of a passenger ship have been executed aiming at gathering data for the future discussion and its facilitation. The paper presents results of the tests together with preliminary conclusions that confirm the need of the revision of the regulation and put forward concerns on application of such values as initial metacentric height (GMo) and righting lever curve (GZ(?)) calculated for a ship laying still for calculation of a ship’s heel caused by turn.

5

The Impact of Sloshing Liquids on Ship Stability for Various Dimensions of Partly Filled Tanks

Krata P.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

|

2013

|

Vol. 7, no. 4

481--489

EN

Liquid sloshing phenomenon taking place in partly filled ships’ tanks directly affects the stability of a vessel. However, only static calculations are carried out onboard ships nowadays and static transfer of liquid weight is taken into account in the course of routine stability calculation. The paper is focused on a dynamic heeling moment due to liquid sloshing in tanks onboard ships. A number of numerical simulations of liquid sloshing taking place in a moving tank is carried out. The wide range of ship’s tanks is taken into account. The conducted CFD simulations are experimentally verified. Finally, the method of an assessment of the liquid sloshing impact on ship transverse stability is worked out. The key point of the method is a dynamic coefficient describing relation of the researched dynamic heeling moment and the quasi-static one in terms of dynamic stability of a vessel which is related to the weather criterion of ship stability assessment.

6

Determination of Inertia Forces Acting on Break Bulk Cargo en Route

Chepok A. O.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

|

2013

|

Vol. 7, no. 4

477--479

EN

The paper presents the analytical method of defining inertia forces that act on break bulk cargo as a result of the oscillatory motion of the vessel exposed to the effect of ambient forces. Considering that the linear models of roll, pitch and heave applicable in this case, the problem is solved by expressing the angle of heel, the angle of pitch, and the amplitude of heave. The obtained functions are differentiated and the inertia forces are determined by means of applying the Newton's second law.