Hui Long Ren

Study on Fatigue Strength of Trimaran Cross-Deck Structure Based on Spectral Method

The stress concentration of trimaran’s cross-deck structure is serious and the problem of its fatigue strength appears particularly important. In this paper, the responses of ship motion and hydrodynamic pressure on ship’s surface in regular waves are calculated using 3D linear potential flow theory, then the stress responses of the hot-spots in regular waves with different wave angles are evaluated by finite element analysis of the global trimaran structure. Based on linear cumulative damage theories, the fatigue damage is calculated according to the direct calculate method used spectral analysis. The result can offer the reference for the trimaran’s design and development.

A Finite Element Method to Simulate Ice Based on Multi-Surface Failure Criterion

A finite element method is introduced to simulate ice failure based on multi-surface criterion. The effects of porosity, temperature and strain rates on the ice mechanic property are taken into consideration. The main principle to simulate environment is explained. Through second developed to the finite element software, the process of ship-ice interaction is simulated. And the ship motion, ice force and ice failure mode are predicted by this method. The result is compared with other papers. the numerical simulation phenomenon is nearly same with the actual process. It suggests that simulation is reasonable, and the model has potential value in simulations of assessing ship strength. The fatigue damage is pointed out to be a special problem in ice-going ship design.

Structural Parametric Modeling and Analysis of a Ship Stiffened Deck Plate Based on the Patran Command Language

As a numerical calculation method in math, Finite Element Analysis (FEA) has been imported into the structural analysis field for more than 30 years. MSC. Patran was launched by the MSC Corporation into the field as a pre-processing and post-processing module of FEA, its strong potential of secondary development has played an important role in the structural parametric modeling analysis. Patran Command Language (PCL) is the built-in language of MSC. Patran. In this paper, in order to introduce PCL’s theory and using method, the author created a GUI by PCL which contains a lot of response functions in a ship stiffened deck plate project.

Study on the Treatment of Nonlinear Roll Damping in Hydrodynamic Calculation and Structural Analysis

In order to insure the consistent wave loads in hydrodynamic calculation and structural analysis, the treatment of nonlinear roll damping in roll motion, wave torsional moment and structural analysis are studied. The nonlinear roll damping moment is applied to the structural model by means of the equivalent nodal forces. Taking a supply ship and a FPSO as example, the calculation results show that the problem of torsional moment distribution divergent on the bow and the unbalanced structural model is improved greatly, which would be helpful to provide the reliable basis to design the structures.

Study on the Effect of Impact Velocity on Slamming Loads

An explicit finite element method which is combined with the Arbitrary Lagrangian-Eulerian (ALE) algorithm is applied to forecast slamming loads during the structure entries into the water. By adjusting the contact parameter, the result of slamming force is improved and this result is compared with the corresponding experimental values to verify the numerical prediction method of slamming loads. By simulating the wedge into the water at a constant speed and evenly variable speed, the effect of the impact velocity on local slamming pressure and global slamming force is studied.

Research on Longitudinal Motion Prediction of Hybrid Monohull Considering Based on Numerical Simulation

The shape of hybrid monohull at the bow is quite complex and the viscosity force is the main component of the damping force in the drainage area of the bow when the ship moves in waves so that the result of the motion predicition by the traditional potential flow method is very different from the result of experiments. This paper tries to use new numerical compute method considering the effect of the viscosity to improve the precision of the sea keeping predicition. Based on the Reynolds Averaged N-S Equations (RANS) method, the paper takes a hrbrid monohull to compute the hydrodynamic coefficients. According to the result of model test, the prediction of the hybrid monohull’s the longitudinal motion in regular waves at speed of 18kn also indicates that RANS method can reflect viscid influence reducing the motion of hybrid monohull in waves.

Mooring System Waterdepth Design of Considering Stiffness and Drift Angle Analysis

The mooring system initial design is quasi-static method based on catenary method. The mooring line stiffness derivation also base on catenary method. In the paper, using jumping wire of high voltage cable calculation method, design the mooring system. Building initial design model, considering the mooring line stiffness and drift angle of mooring line and structure.

Risk-Based Inspection Analysis of Jacket Platform

Risk-based inspection analysis is a key part of structure integrity management (SIM) process for ensuring the fitness-for-purpose of offshore jacket platforms. For the platforms locates in the South China Sea which often suffer severe sea condition, it is essential to employ an appropriate assessment method to determine the structure strength and increase the platforms’ safety. This paper presents a comprehensive risk-based inspection method for in-service jacket platform structure. Nonlinear pushover analysis is used to carry out the ultimate bearing capacity and failure consequence of the structure, in which the platform ultimate bearing capacity is characterized in terms of the Reserve Strength Ratio (RSR) and Residual Capacity Ratio (RCR). Taking the four limit state equations of structure member and limit state judgment criteria of structure system into consideration, the structure reliability analysis is proposed with the combination of extreme probability model of environment loads. On this basis, a risk matrix will be formed and a risk-based inspection plan can be developed. A case study of jacket platform located in the South China Sea is used to illustrate the application of the structure assessment approach.

Numerical Simulation of Water Impact of 2D Wedge with Different Density

It remains unresolved to study the relation between the density of wedge and its impact. Fluent is applied to simulate its mechanism with 6DOF model. After the comparison of numerical result and the theoretical, it matches good and then the transient free surface scene is observed. Thus Fluent is able to solve this kind of non-linear problem. And the effect of density of wedge on the slamming character is also studied.

Numerical Calculation of Slamming Pressure on Wet-Deck of Trimaran

Due to the air cushion and splash the slamming into the water of Trimaran connecting bridge are highly nonlinear, this paper discusses the problem of typical Trimaran sections slamming into the water by use of general finite element software MSC.Dytran. Through secondary development program implemented the initialization of water pressure, considered the coupling structural-air-water, a simulation method for connecting bridge slamming into the water has developed. The results show that the method meets the engineering precision and can give reference for Trimaran construction and operation.