Analysis of cracked shear deformable plates by an effective meshfree plate formulation

Solitary wave-induced forces on horizontal circular cylinders: Laboratory experiments and SPH simulations

A novel meshfree discretization technique in terms of the reproducing kernel particle method is presented for accurately evaluating mixed-mode intensity factors of cracked shear-deformable plates. Mindlin–Reissner plate theory is adopted to solve the cracked plates problem in the Galerkin formulation, considering transverse shear deformation. The diffraction method, visibility criterion and enriched basis are included in the generation of meshfree interpolants for the modeling of fracture. In this work, numerical integration is treated using the stabilized conforming nodal integration (SCNI) and subdomain stabilized conforming integration (SSCI). The J-integral (contour integral) is employed to analyze the fracture mechanics parameters. SCNI/SSCI is thus adopted to evaluate the contour integral and to split the original J-integral into symmetric and asymmetric J-integral values. They are calculated by decomposing the smoothed displacement, moment and shear force quantities into symmetric/asymmetric parts. In addition, a displacement ratio method is introduced to divide the asymmetric J-integral value into corresponding moment and shear force intensity factors. The accuracy of the intensity factors and the path-independent properties in mixed-mode fracture problems are critically examined through several numerical examples.

Accurate evaluation of mixed-mode intensity factors of cracked shear-deformable plates by an enriched meshfree Galerkin formulation

The State of Bahia has one of the largest port complexes in Brazil, that consists of public ports and private use terminals. One of which is specialized with a cargo carrying capacity of about 530 thousand TEUs (Twenty-foot Equivalent Unit) per year. On the other hand, the container terminal at the port of Genoa, Italy, has a similar capacity but has been performing better than the Brazilian one. The present study evaluates the differences and similarities between these ports, in the context of engineering, environmental sustainability and some topics of the port regulatory framework that can influence productivity. Based on the arrival and service rates of the ships and their respective probability distributions, a mathematical model of queuing theory was developed that indicates the port occupation rate, the time and the average number of ships in the queue, in a process with which one can assess the environmental impact of these terminals. (naval-port infrastructure and queuing theory) and in environmental sustainability, as well as in some points of the regulatory framework and logistical infrastructure of both countries that can influence and reveal the competitiveness of these ports. Based on vessel arrival and service rates and their consequent probability distributions, in addition to other constraints, the queuing model reveals the time and average number of ships in process, the port occupation rate, and the expected probability of this finding variable, may provide a possibility of fine payments for delay in services, thus serving as the efficiency indicators of port operation. The results obtained here, and their interpretations, are limited to the time of their respective data collection, as well as to the reliability of information that was possible to obtain at the time of the technical visits and professional meetings held. They are also limited to the consultations made to the electronic pages of the terminals and institutions that control local port operations. The present work is in the context of other researches already carried out. Camelo et al. (2010), used queuing theory to simulate the behavior of the row of iron ore vessels in the port of Ponta da Madeira, Brazil, with the aid of the Arena® software and found high berth occupation rates, recommending investments in the expansion of its capacity to meet the expectations of growing demand for ores in the world market. In this same direction, Schoreder (2014) simulated the operational behavior of the container terminal at the port of Durban, South Africa, based on the operation of the queue system of the container terminal at the port of Rotterdam from the logic of model construction simulated

Progress in Maritime Technology and Engineering : Proceedings of the 4th International Conference on Maritime Technology and Engineering (MARTECH 2018), May 7-9, 2018, Lisbon, Portugal

Effect of trim on container ship resistance at different ship speeds and drafts

The objective of this paper is to perform trim optimization on a 4250-TEU container ship based on the influence of trim on the resistance by using computational fluid dynamics (CFD) in conjunction with towing tank tests. First, the International Towing Tank Conference (ITTC) procedures were applied to uncertainty analysis of CFD and the CFD procedure was further verified and validated through three representative resistance curves obtained by the tests. Next, a series of resistance curves in different conditions with varied drafts and trims were obtained by the CFD computations for the model to provide data source to analyze the influence of the trim on the resistance. Results indicate that the variation of wave-making resistance due to trim dominates that of the total resistance. Finally, the resistance data for the model were converted to the engine power of the real ship. At each speed, the response surface of engine power with respect to drafts and trims was constructed and thus a trim optimization program was developed. The real ship operated under the instruction of the trim optimization program can save energy and reduce emissions significantly.

A Study on Trim Optimization for a Container Ship Based on Effects due to Resistance

Fully nonlinear simulations of interactions between solitary waves and structures based on the finite element method

A surface panel method for a boundary-value problem with the free surface is proposed to predict ship wave resistance under different trim conditions based on a so-called double-model solution. The free surface boundary condition is linearized with respect to the oncoming flow and computed by a four-point finite difference scheme. Sample computation for Wigley hull is carried out to demonstrate the effectiveness and the robustness of the method. A hull model is taken into account at two different displacements with respect to trim conditions of lower wave resistance. It is demonstrated by calculation and experiment that the wave resistance under the trim conditions provided by the proposed method is lower than that under the initial conditions.

https://journals.sagepub.com/doi/pdf/10.1155/2013/378140

Trim Optimization of Ship by a Potential-Based Panel Method:

A modified admiralty coefficient for estimating power curves in EEDI calculations

The paper aims at conducting trim optimization for a hull to reveal the influence of trim on wave resistance by a potential-based panel method coupled with a response surface method. First, a numerical program for solving the linear free-surface flow problem of a hull moving with a uniform speed in calm water is built by the panel method. The S60 hull model is used to validate the numerical procedure. Next, calculation for hull is performed with two different trims at a wide range of Froude number; resistance test is conducted to validate the numerical method in demonstrating the influence of trim on wave resistance. Finally, a response surface of wave resistance is constructed with respect to variations of trim and Froude number, using the database of wave resistance calculated by the surface method. In this way, a framework is developed to perform trim optimization. The optimum trim point for the present hull shows a significant improvement in both wave resistance and total resistance, compared with that of even keel and the worst trim point. The optimization framework is proved to be effective in energy saving due to resistance reduction.

Jianglong Sun

Papers

A Study on Trim Optimization for a Container Ship Based on Effects due to Resistance

Fully nonlinear simulations of interactions between solitary waves and structures based on the finite element method

Trim Optimization of Ship by a Potential-Based Panel Method:

A modified admiralty coefficient for estimating power curves in EEDI calculations

On resistance reduction of a hull by trim optimization