International Shipbuilding Progress - Volume 47, issue 449

Authors: Westlake, P.C. | Wilson, P.A.

Article Type: Research Article

Abstract: A multiparameter conformal mapping technique is presented which permits the accurate description of realistic ship sections. The solution of a nonlinear set of equations describing the transformation of a circle to the arbitrarily shaped section is linearised using a new method which produces a monotonic relationship between coordinates in the physical and reference planes. This feature allows the mapping of reentrant sections such as large bulbous bows and the inclusion of features such as bilge keels and shaft …brackets. The assumed form of the conformal mapping permits asymmetric sections to be represented. The sections can be successfully transformed at different heel angles. Show more

Citation: International Shipbuilding Progress, vol. 47, no. 449, pp. 5-22, 2000

Authors: Shyu, K.L. | Kuo, H.C.

Article Type: Research Article

Abstract: This paper presents a study of the dynamic responses of a tuned liquid damper (TLD) in frequency domain. The tuned liquid damper uses air to adjust the natural frequency of the TLD and uses liquid inside a U-shape tank as the mass of liquid damper. The equation of motion ofa structure mounted with a U-shape TLD is transformed into frequency domain. The damping ratios of the U-tube tank with various orifice diameters were determined by experiments. The …vibration behaviours of the structure with and without the U-shape TLD subjected to a simple harmonic excitation were examined in the frequency domain. The effects of both mass ratios (mass of U-shape TLD/mass of structure) and damping ratios of the U-tube tank on vibration reduction were studied. The responses of the structure were compared to those obtained from a structure mounted with a solid spring-mass damper. Show more

Citation: International Shipbuilding Progress, vol. 47, no. 449, pp. 23-36, 2000

Authors: Chatterjee, P.C. | Das, P.K.

Article Type: Research Article

Abstract: The critical nature of bulk carrier structures has been dramatically demonstrated over the last decade by the number of serious casualties that these ships have suffered. It is crucial to account for the deterioration that is expected due to corrosion and wastage. A Panamax class single hull bulk carrier which was designed and classed using old prescriptive rules has been analysed in the ABS SafeHull system to reflect corrosion related structural behaviour. A number of critically …stressed areas, successfully identified by SafeHull, are presented in this paper. Show more

Citation: International Shipbuilding Progress, vol. 47, no. 449, pp. 37-52, 2000

Authors: Chuang, Fang | Guangwu, Zeng | Zhongyi, Fan

Article Type: Research Article

Abstract: In this paper, the ultimate strength of high speed craft is studied by analyzing the possible failure modes. A method is presented to estimate the ultimate longitudinal strength of the hull girder and an example is given by using the proposed method. Finally, the strength criteria are briefly discussed combined with the requirements of Rules.

Citation: International Shipbuilding Progress, vol. 47, no. 449, pp. 53-60, 2000

Authors: Hofman, Milan | Kozarski, Vladan

Article Type: Research Article

Abstract: When designing a vessel intended to sail in shallow waters it is of great practical importance to judge, in most early stages, whether the influence of water depth on wave-making resistance is negligible (sub-critical region), unfavorable (critical region) or favorable (super-critical region). To enable that, the present investigation proposes a new type of resistance charts suitable for the preliminary assessment of the shallow water influence. The charts are obtained by systematic numerical calculation of, so-called, …Srettensky integral for number of different ship forms and different dimension ratios. Comparation of the results with some published experimental data shows a good agreement of the main particularities of the proposed charts. Exception is the lower boundary of the critical region, which has to be subjected to some further analysis. Show more

Citation: International Shipbuilding Progress, vol. 47, no. 449, pp. 61-76, 2000

Authors: Matusiak, Jerzy

Article Type: Research Article

Abstract: Two problems related to the loss of ship stability in waves are considered. A generation of non-repeatable irregular waves used in numerical simulations or model tests is discussed first. Then the problem of cargo shift onboard a ship in waves is studied. A mathematical model of the forces acting on a concentrated piece of cargo in a moving frame is derived. The conditions necessary for secure cargo transportation are presented. The model of cargo shift is …coupled with a non-linear model of ship behaviour in beam waves. As an example, the presented method is used to study the problem of capsizing of a ship. The effects of ship stability, method of generating irregular waves, and non-linearities of ship motion on the probabilities of cargo shift and capsizing of a ship are discussed. Show more

Citation: International Shipbuilding Progress, vol. 47, no. 449, pp. 77-93, 2000

Authors: Fang, Ming-Chung | Lin, Han-Ping

Article Type: Research Article

Abstract: In the paper, the radiation problems of a moving ship are solved by using the 3D source distribution technique incorporated in a panel method. The added mass and damping coefficient with speed effects are obtained through the modifications of the pressure calculation, body boundary condition and additional contour integral along the interaction of hull surface and the free surface. In order to eliminate the mathematical difficulties associated with the numerical evaluation of the exact Green function, …a simplified free surface condition is assumed. The series expansions of the Telste & Noblesse algorithm and the complex plane contour integral of the Shen & Farell algorithm are used for solving the corresponding Green functions and their derivatives. Three different numerical formulas are derived to calculate the added mass and damping coefficient and are discussed in the paper. The three-dimensional method developed in the paper can offer an efficient analytical tool for estimating the corresponding hydrodynamic coefficients of an oscillating ship with speed in calm water. The effect of steady flow is generally small in the present radiation problems and may be negligible. However, the effect of the water line integral is significant for pitch and yaw modes and may not be neglected. It is also found that using the techniques incorporated with a suitable body mesh distribution can lead to satisfactory results. Show more

Citation: International Shipbuilding Progress, vol. 47, no. 449, pp. 95-124, 2000