The Application of Roller Rigs to Railway Vehicle Dynamics

Roller rigs have been built world-wide to research into the dynamics of railway vehicles and they have particularly been applied to the development of high-speed trains. This survey takes into consideration both full scale as well as small scale model roller rigs. Besides performance, most important experimental work and the emphasis of application, the scaling strategies of model test rigs and the differences involved in roller rig experiments are treated. Suggestions for potential future uses and developments are also given for this tool which is useful for demonstration and analysis of railway vehicle dynamic behaviour.     

Consistency in the development of performance assessment methods in the maritime domain

The maritime industry is considered to be a backbone of the global economy. It is therefore imperative to ensure that maritime operations run safely and efficiently. Assessment of maritime performance is necessary for designers and engineers to be able to pinpoint the weakest links in the system and make impactful system improvements. The current article presents a systematic quantitative literature review of research on performance assessment in the maritime industry with the goal of establishing an understanding of accuracy and consistency in the development of methods used to assess performance. The review focuses on four major segments within the industry—port logistics, ship handling, safety and environmental research—and investigates their uses in developing accurate and consistent performance assessment methods. After the completion of an exclusion process, 62 articles published in a wide range of academic journals were used in the analysis. Two important conclusions were drawn from the analysis. First, performance assessment is generally consistent throughout the maritime industry; most papers used accurate and consistent approaches to develop the methods (n?=?43). A subsequent bivariate analysis revealed a call for increased attention to the development of assessment methods within the maritime segment of ship handling. The current study suggests and discusses certain directions with regard to assessment research in the maritime industry.     

Integrated numerical analysis of an iceberg collision with a foreship structure

This paper presents results of integrated elasto-plastic analyses of ship-iceberg collisions based on continuum mechanics modelling of both bodies. The collision simulation was simplified by splitting the problem into external and internal mechanics, which are both discussed in detail. A simplified formulation was used to obtain the demand for energy dissipation in a ship-iceberg collision. The internal mechanics was assessed by means of the explicit non-linear code LS-DYNA 971. A new iceberg material model was used to simulate the iceberg behaviour during the impact. The foreship structure was modelled by shell elements. Rupture due to excessive straining was taken into account by a widely used steel fracture model. The relative strength of the ship and iceberg was varied by adjusting the stress-strain properties of the steel. Two iceberg shapes were investigated: a half-sphere with a radius of 2000 mm and another half-sphere with a radius of 1000 mm. The point of impact of the iceberg was assumed to be either the web frame or midway between web frames. The evolution of contact pressure and the distribution of damage to the foreship and crushing of the iceberg were studied comprehensively.     

Price formation of dry bulk carriers in the Chinese shipbuilding industry

In this paper, we present, for the first time, the price formation of Chinese dry bulk carriers based on the historical shipbuilding contract prices. Price determinants include generic market factors as well as Chinese elements. Principal component regression analysis is employed as the solution for the multicollinearity problem among explanatory variables. The result indicates that the time charter rate has the most significant positive impact on shipbuilding price; increases in three other factors, namely the cost of shipbuilding, the price-cost margin and the shipbuilding capacity utilisation, have positive influences in the descending order. Unlike the traditional perception of newbuilding price that shipbuilding cost has the most significant effect, we assert that the most important role the time charter rate plays is attributed mainly to the ‘China Factor’ in the bulk carrier sector. In addition, simulations are performed to investigate what would happen to the Chinese dry bulk carrier prices under changes in the time charter rate and shipbuilding cost. The findings are useful for Chinese shipyards, shipowners and emerging shipbuilders.     

Monitoring of ship damage condition during stranding

This study proposes a new procedure for the estimation of stranding forces and their contact positions. The method is based on the measurement of a few characteristic on-site parameters, i.e., the draughts and bending moments acting on a stranded ship. A procedure that estimates penetration into the ship bottom based on knowledge of the resistance versus penetration relationship is also presented. The seabed topology is parameterized by a paraboloid. This geometry can, in principle, characterize a wide range of obstructions, from sharp rocks to large shoals. Nonlinear finite element analysis is used to simulate various stranding situations and to generate the corresponding resistance versus penetration curves. The present method provides insight into the identification of real stranding scenarios in terms of the location of obstructions, their possible shapes and the corresponding resistance-penetration curves. The proposed methodology represents a first step towards a tool for quick decision making during salvage operations. The ultimate goal is to allow near real-time prediction of the risk of penetration into cargo tanks and hull girder failure. To demonstrate the effectiveness of the proposed method, it is applied to a simulated trial stranding scenario.     

Wave analysis of porous geometry with linear resistance law

The wave diffraction-radiation problem of a porous geometry of arbitrary shape located in the free surface of a fluid is formulated by a set of integral equations, assuming a linear resistance law at the geometry. The linear forces, the energy relation and the mean horizontal drift force are evaluated for non-porous and porous geometries. A geometry of large porosity has an almost vanishing added mass. The exciting forces are a factor of 5–20 smaller compared to a solid geometry. In the long wave regime, the porous geometry significantly enhances both the damping and the mean drift force, where the latter grows linearly with the wavenumber. The calculated mean drift force on a porous hemisphere and a vertical truncated cylinder, relevant to the construction of fish cages, is compared to available published results.