Analysis on the Yield Strength and Structure Fatigue of

a Membrane LNG Carrier with Global Finite Element Method

 

WANG Jia-ying，JIN Yan-zi，YANG Ren-ji，LIU Jin-feng

（Hudong-Zhonghua Shipbuilding (Group) Co., Ltd., Shanghai 200129, China）

Abstract: The global yield strength check and fatigue analysis based on finite element method (FEM) are carried out with refined mesh for the structural design of membrane LNG (Liquefied Natural Gas) carriers and the 3D wave loads prediction code of ABS-DLA/SFA series software is used to perform the long-term prediction of the random wave loads respectively under five typical loading conditions in accordance with ABS global FEM direct strength analysis guide. Based on the prediction result, 15 parametric groups of design waves are calculated for each loading condition to determine the global structure stress distribution under each load combination, and thus to complete the yield strength check. The key node region of intersection between deck machinery room and trunk deck are taken as the example to accomplish the local strength analysis with fine mesh and several design improvements are made to solve the problem of stress concentration. According to the two common typical operational loading conditions and the operational requirement of 40a fatigue life in the North Atlantic Ocean, the hotspot stress transfer functions of two typical refined locations are computed based on the ABS global FEM direct strength analysis guide. The fatigue accumulation damage and fatigue life are obtained through spectral analysis to complete the fatigue strength check. The global strength and fatigue analysis method can be used in the structural analysis of other ultra large ships.

Key words:large LNG carrier; global FEM strength analysis; fine mesh; fatigue analysis

 

 

 

Modeling and Safety Control of Deepwater

Drilling Riser Angles

 

WANG Fang¹，BAI Yong²，XU Feng³

（1. School of Mechanical Engineering, Hangzhou Dianzi University, Hangzhou 310018, China;

2. College of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310058, China;

3. Wuhan Second Ship Design and Research Institute, Wuhan 430064, China）

Abstract: From the aspect of safe operation in collaboration with the drilling platform above the water and the risers beneath, this study proposes a station keeping method which considers the mechanical response constraints of the drilling risers in the dynamic positioning close-loop control, so as to achieve the dynamic positioning of the surface drilling vessel or platform based on the riser angle responses. A control model is established for riser motion with finite element method, which includes riser system mass, system stiffness, structure damping and hydrodynamic loads. The relative motion model between the movement of the surface floating body and the top and end angles of the underwater riser is established depending on their low frequency motion characteristics. In this way, the dynamic positioning control method is designed according to the riser motion response, and the safety control of the top and end angles of the risers is realized. Simulation result shows that the proposed method is feasible. The surface floating body can track the new expected optimal position more rapidly in case there are transient external environmental loads, and thus to ensure the riser operation within safety limits.

Key words:dynamic positioning; station keeping; drilling riser; drilling platform

 

 

 

Installation and Hook-up Technology for

FPSO Single Point Mooring System

 

LIANG Ji¹，WEI Zhuo²，YU Guo-he²，REN Xiang²，LU Jing-jing²

（1. Shenzhen COSL Deepwater Technology Co., Ltd., Shenzhen 518067, China;

2. Subsea Tech Operating Company, Geophysical COSL, Tianjin 300451, China）

Abstract: Single Point Mooring (SPM) system is one of the core components of FPSO (Floating Production Storage and Offloading) facility, which should be installed before FPSO is towed into the field for subsequent hook-up. This paper systematically introduces the installation and hook-up methods of a SPM system for a specific project at the South China Sea, where OrcaFlex software is used for the simulation and analysis of each operation stage. The installation process of the SPM system consists of 6 stages, i.e. deployment of anchor, laying the lower part of anchor leg, preload of anchor leg, laying the upper part of anchor leg, towing and positioning of the single point buoy, and the hook-up between the mooring system and the sing point buoy.

Key words:FPSO; Single Point Mooring system; installation and hook-up; OrcaFlex; dynamic analysis

 

 

 

Analysis of the Acceleration of Ship and

Main Engine under Heavy Load

 

WANG Dong-dong，DENG Gao-xiong，ZHOU Yong-xiang，WANG Lei

（CSSC-MES Diesel Co., Ltd., Shanghai 201306, China）

 

Abstract: To solve the problem of ship acceleration at rough sea and the problem of main engine operating overtime in the barred speed range, this paper analyzes the reasons of the problems from the viewpoints of propeller matching and main engine internal design. Focusing on the power margin of the barred speed range, some countermeasures are proposed after a comprehensive study on the light propeller margin, barred speed range, MAN main engine torque output, etc.

Key words:marine low speed diesel engine; severe sea condition; barred speed range; acceleration; propeller margin; dynamic limiter function

 

Difficulties and Countermeasures for the Application of

Dual Fuel Engine on LNG Carriers

 

DUAN Bin，WANG Zhi-min

（Hudong-zhonghua Shipbuilding (Group) Co., Ltd., Shanghai 200129, China）

Abstract: This paper mainly introduces the application of dual fuel engine on the Liquefied Natural Gas (LNG) carriers with electrical propulsion. The safe zones and hazardous zones in the engine room must be rearranged according to the special design and safety precautions of the gas pipelines across the engine room. The major pipelines of exhaust gas system, lubricate oil system and cooling water system as well as the emergency cut-off system with different control levels need to be designed specifically. Moreover, configuration of safety devices for the gas detection system and the forced ventilation system needs to be considered carefully. When the preliminary design is accomplished, it is necessary to have a comprehensive analysis on the potential risk and fault diagnosis to guarantee the safety and reliability of the dual fuel power system.

Key words:LNG carrier; dual fuel engine; dual-fuel diesel electric propulsion; gas system

 

 

Design of Low Voltage Power Distribution System

for Very Large Container Ship

 

FU Xiao-hong，LU Shi-ping，XIE Song-qing，ZHOU Yi-long，XIA Jun

（Marine Design & Research Institute of China, Shanghai 200011, China）

Abstract: With the development of large scale container ships, the traditional AC220V low voltage power distribution network can no longer meet the requirements of very large vessel, and the problem of voltage drop is becoming more and more serious. Therefore, technical and economical analysis on the low voltage power distribution of Very Large Container Ship (VLCS) is carried out, and a distributed low voltage power distribution network framework is proposed based on the “twin islands” arrangement of VLCS. Comparison and analysis on the traditional and the distributed low voltage power distributions network frameworks are performed in detail with calculations on the reduction of cable voltage drop, alleviation of cable channel congestion and reduction of manual cost. The trial onboard validates that the distributed type of low voltage power distribution system can effectively solve the problems of voltage drop and cable channel congestion, which could be referred by the subsequent low voltage power distribution system design for VLCS.

Key words:electrical engineering; very large container vessel; low voltage power distribution system; distributed system

 

Design of the Security System for Jack-Up Drilling Rig

 

YUAN Fei-hui，CHEN Lin

（Shanghai Waigaoqiao Shipbuilding Co., Ltd., Shanghai 200137, China）

Abstract: Security system of Jack-up drilling rig is a kind of protection system for the purpose of accident pre-caution, people and equipment protection and production benefit maximization on the premise of safety. This paper introduces the composition of the security system and its key index, the function design of the system and the methods used in safety integrity level calculation, where reliability block diagram is used in calculating the safety integrity level of the typical safety control process.

Key words:safety integrity level; availability; voting architecture; logic; shutdown

 

Research on Waterjet Propeller Thrust Allocation Based on Joystick Operating System

 

XIE Xiao-ying，HAO Fang，LIU Yun

（Shanghai Marine Diesel Engine Research Institute, Shanghai 201108, China）

Abstract: Asjoystick operating system is seldom used in water-jet propellers in China and it is very difficult to control ship translational motion manually according to the 6 parameters of the two propulsion units, this study investigates the thrust allocation strategies based on the joystick operating system. Thrust allocation is one of the key technologies of the joystick operating system to allocate the thrust forces on each propeller according to the total force from the joystick. Based on the characteristics of the water-jet propeller, the cascade generalized inverse method with group biasing is proposed as the control strategy. As energy priority and heading preference method are taken as the basis, the thrust allocation strategy can adaptively correct deviation and at the same time to ensure maneuverability. The simulation result shows that the strategy matches the excellent maneuverability of water-jet propellers.

Key words:water-jet propeller; surface vehicles; joystick operating system; thrust allocation

 

Precision Control of the Watertight Door

on 45000t Con-Ro Ship

 

WANG Shou-xiang，GONG Jin-di，LIU Yang

（Hudong-zhonghua Shipbuilding (Group) Co., Ltd., Shanghai 200129, China）

Abstract: In order to control the installation precision of the door frame inside hull structures, a study was carried out on the watertight door precision control of a 45000t Con-RO ship block that only contains watertight door structures. The construction method of the block was analyzed and the construction technique was improved by properly arranging the installation procedure of the door frame structure construction to reduce structure deformation. At the same time, a device with high accuracy was used for the measurement followed to make sure that the precision is constantly controlled within the allowance. The welding method was also studied to improve the welding technique, where gradual back welding method was used to control the heat so as to reduce welding deformation. The studies on watertight door frame structure installation technique and welding technique combines theory with practice and derives a series of valid construction techniques which can ensure the effective precision control of the door frame installation and its watertight performance and provide reference for the subsequent block construction of this series of ships.

Key words:Con-Ro ship; watertight door; construction technique; precision control

Precision Control Technique for Ultra-High Guide Frame onboard 45000t Con-Ro Ship

 

CAI Peng-tian，YANG Li-zhi，ZHANG Chen-jun

（Hudong-zhonghua Shipbuilding (Group) Co., Ltd., Shanghai 200129, China）

Abstract: The45000t Con-Ro ship is specially designed without lashing and hatch cover, but there is an ultra-high guide frame in a maximum length of 30m to keep the position of containers. In order to make the ultra-high guide frame installed precisely and in compliance with the rules and regulations, the traditional installation technique and precision control are compared and analyzed according to the special structure and function of the ultra-high guide frame, and new installation procedures are proposed to enhance the precision control at different stages. This paper introduces the structure characteristics of ultra-high guide frame for the type of ship, elaborates the difficulties and the precision planning of the installation, explains the pre-assembly technique of the block, and describes in detail the key points of precision control at different stages of the installation. The procedures are validated feasible in the container lifting test and the result shows that the proposed method can effectively guarantee the construction precision of the ultra-high guide frame without losing production efficiency. The study could provide reference for the subsequent products which need to improve construction quality and efficiency.

Key words:Con-Ro ship; ultra-high guide frame; precision control

 

New Requirements on Safe Practice for Container Securing

 

MA Xiao-ming

（Rules and Technology Center,CCS, Shanghai 200135, China）

Abstract: IMO (International Maritime Organization) has issued some new requirements on safe practice for container securing to provide safer working conditions for the workers involved in the container securing on deck. The new requirements include the arrangement of safe access and illumination, design of securing devices, training of workers, as well as the procedures of operation and maintenance. As the application of the new requirements will influence the design and construction of containerships, this paper gives a deep explanation of the new requirements with emphasis on the analysis of the safe access arrangement which influences the design and arrangement of containership most greatly. It takes a containership under construction as example to validate the influence of the new requirements on the ship. Finally, suggestions on the design optimization of general arrangement are proposed on the premise that the new requirements are fully implemented to guarantee personnel safety.

Key words:container; safe access; safe securing

 

Development of Digital Asset Management System for Shipyard Block Stock Based on VR Technology

 

WANG Zhen，ZHENG Peng-fei，DING Wei-jie，YU Ling-yun，HE Di，QIU Yu-zhou

（China Shipbuilding NDRI Engineering Co., Ltd., Shanghai 200063, China）

Abstract: This study developed a digital asset management system for shipyard block stock in 3D visualization environment with Virtual Reality (VR) technology and database technology on the basis of Model-Based Enterprise (MBE) theory, where a domestic shipyard was taken as the example. The system not only provides the managers with a unified, highly efficient, real-time platform for dynamic data inquiry and decision making, but also lays a technological foundation for the life-cycle management regarding shipyard design, construction and operation.

Key words:MBE; virtual reality technology; asset management; visualization; Unity3D

 

Ship Pre-erection/Erection Simulation and

Optimization Based on Work Package/Work Order

 

ZHU Ming-hua¹，SHAN Xiao-fen¹，MAO Shen-fei¹，ZHU Ren-gui²

（1. Jiangnan Shipyard (Group) Co., Ltd., Shanghai 201913, China；

2. CSSC Huangpu Wenchong Shipbulding Co., Ltd., Guangzhou 510715, China）

Abstract: According to the work breakdown practice of work package/work order (WP/WO) in the pre-erection/erection area, this paper carries out systematic and comprehensive analysis on the basic data, production technology and process, facility and equipment as well as the resources during pre-erection/erection, and establishes the pre-erection/erection simulation model based on WP/WO plan. Assessment is performed in a virtual environment before production to reveal potential problem and thus to make the design, production and management more accurate, effective and in a more orderly way. Analysis of a practical example shows that the pre-erection/erection simulation based on WP/WO work plan is an effective new technology that provides decision basis for fine management.

Key words:WP/WO; pre-erection/erection; simulation; optimization