10 0 0 0 OA ホーバークラフトの操縦性シミュレーションについて
Focussing on the sea-going maneuverability of a 105-passenger hovercraft, the authors made investigations through series of model tests and computer simulations. The wind forces acting on a scale model, which represents superstructure and cushion form, were measured in a wind tunnel test. Oblique towing tests with self-lifting model were carried out for the hydrodynamic characteristics between cushion skirt and water plane. Regarding the characteristics of control surfaces, the force measurement tests with ducted propeller and rudder in wind tunnel were carried out. Based on these results of model tests, the authors developed a simulation program which employs proper mathematical models for each force components, namely cushion skirt, wind, propellers, rudders and thruster. The output of simulation showed fairly good agreement with the results of actual sea trial. Especially in the case of course keeping in beam wind, the reverse of check-helm direction around Froude number of 1.0 experienced in actual operations were confirmed through computer simulation. Lastly the results of extensive investigations on the sea-going maneuverability of the hovercraft are explained.
In this paper the extended penalty function approach to dynamic contact problems recently proposed by Asano is further discussed. The equation of motion, in which velocities as well as displacements are constrained by the physical consideration, coincides with the one based on the virtual work principle given by Asano. The optimal penalty numbers in this approach are discussed by using a simple two-element model. The obtained results are applied to the finite element analysis of contact-impact problem of two elastic rods and the validity of the present method is confirmed through the comparison of the numerical results with the exact solution based on the one-dimensional wave propagation theory. The present method is also applied to the friction-excited vibration of a two-dimensional elastic block on a sliding belt, and it is shown that the kinematic coefficient of friction can be lower than the static one in the camplete system even when they are assumed to be equal to each other on the interface between the block and the belt.
1 0 0 0 LPGタンク隅肉溶接部の疲労挙動について
In view of safety design against fatigue failure in cylindrical storage tank of low temperature use, low cycle and low temperature fatigue behaviour of shell to annular tee-fillet welded joint in tank was investigated experimentally and analytically, in case of liquefied propane gas tank, using a displacement-controlled bend test of model specimens. The experiments and analyses were done either by strain and displacement measurements around weld toe in annular plate under cyclic deformation or by finite element analysis mainly to clarify quantitatively the effects of type of weld joint as well as dimensions of weld joint, including the effects of annular plate thickness, on the fatigue crack initiation life of tank. Principal results obtained are as follows. (1) In bend test of model specimen, a distribution of strain range in front of weld toe indicates that its maximum value is found at weld toe as far as the deformation range examined, although maximum value of strain distribution is found at 5-10mm distant from weld toe under large extent of deformation. (2) Experiments and analyses show that there is no difference practically between fillet weld joint and full penetration joint in cyclic deformation as well as in fatigue strength. (3) The expression of evaluating the fatigue crack initiation life in the displacement controlled bend test of model specimen was derived in terms of weld joint parameters, which is [numerical formula] where N_c,._p, t. SL denotes fatigue crack initiation life, weld toe radius, displacement range at the loading point, annular plate thickness, and leg length of shell plate respectively. (4) By introducing a parameter _<s-A>, an angle which defines an extent of deformation around weld toe, the fatigue crack initiation life in tank is predicted from the results on model specimen. (5) The finite element analysis shows that as to the bend test on model specimen, the increase of annular plate thickness decreases the initiation life in displacement controlled test, and increases it in load controlled test. However, the incorporation of the results on model specimen to the behaviour in deformation of the tank indicates that these two express-ions are essentially the same as far as the fatigue crack initiation in tank concerned. As of now, it seems that the thicker the annular plate becomes the longer the fatigue crack initiation life in this type of tank.
1 0 0 0 球殻の耐圧強度に関する実験研究
- 著者
- 金井 一彦 森鼻 英征 山崎 敏樹 寺田 邦夫
- 出版者
- 日本造船学会
- 雑誌
- 日本造船学会論文集 (ISSN:05148499)
- 巻号頁・発行日
- no.132, pp.269-279, 1972
- 被引用文献数
- 1
In order to obtain the collapse strength data on the spherical shells suitable to the pressure capsule of DSSV, collapsing tests were conducted using spherical shell models by means of MHI 1,200kg/cm^2 hydrostatic tank. These models were made from several kinds of materials including ultra-high yield strength steels such as 18% Ni maraging steel, 10% Ni dual-strengthened steels etc., and machined into near-perfect spherical shape or spheres with initial imperfection of various thicknesses. From these experiments the following conclusions are obtained : (1) Collapse pressure of relatively thick shells (h_a/R_<10>≧0.03) agrees to the theoretical inelastic buckling pressure by Gerard et al. (2) The effect of initial imperfections are evaluated by local radius in case of relatively thick shells. But for thinner shells, this method is not sufficient and nonlinear elasto-plastic analysis will be required. (3) Present results will not always agree with Krenzke's data, especially in thinner shells with flat spot. (4) Fracture appearance of collapsed shells are closely related to the fracture toughness of materials.
1 0 0 0 遺伝的アルゴリズムを用いた自動ネスティングシステムの開発と実用化
- 著者
- 山内 重樹 手塚 研治
- 出版者
- 日本造船学会
- 雑誌
- 日本造船学会論文集 (ISSN:05148499)
- 巻号頁・発行日
- no.178, pp.707-712, 1995
- 参考文献数
- 4
- 被引用文献数
- 4 6
Nesting in shipbuilding is work that complicated parts of various sizes are arranged in steel plate as many as possible. The work has been done by experts. We have developed the automatic nesting system by use of Genetic Algorithm (GA) and new algorithm which are introduced from heuristic rules which the experts have. We call the algorithm "geometrical simplification of parts pairing algorithm" and "grouping algorithm". This paper describes that the combination with GA and new algorithm which we propose is effective to the processing speed of the system and the scrap ratio of nesting and that the system is available for practical use.
1 0 0 0 プロペラ後流渦と揚力面の数値解析
In recent years, a highly advanced lifting surface method with high accuracy has been required in order to design the various types of propellers which demand high efficiency and to reduce ship vibration and noise. In this paper, an improved lifting surface procedure based on the vortex lattice method is presented. For the determination of a trailing vortex wake geometory, a numerical iterative procedure is described. The numerical results on propeller slipstream give a good agreement with the measured values by laser doppler velocimeter. The present method is applied to calculate the open water characteristics of a propeller. And a quasi-steady technique based on the present method is adopted to calculate the fluctuation of propeller forces and cavitation patterns behind the ship's wake field. The advantages of the present method are shown by comparing the numerical results with the experimental data of conventional and highly skewed propeller.