• Journal of the Society of Naval Architects of Korea
• /
• v.51 no.1
• /
• pp.42-50
• /
• 2014

Lifting lugs are frequently used in shipyard to transportate and turn over blocks. As the shipbuilding technology develops, blocks has become bigger and bigger, and block management technology takes a more important role in shipbuilding to enhance the productivity. For the sake of economic as well as safe design of lug structure, more rigorous analysis is needed. In this study in order to investigate the strength characteristics of two type of lug, that is, D and T type lugs, non-linear strength analysis has been carried out to compare the ultimate strength characteristics of two types of lug varying in-plane and out-of-plane loading directions. Based on the present numerical analysis results, it can be drawn that T type lug is superior to D type lug from view points of ultimate strength and deformation.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2000.04a
• /
• pp.189-194
• /
• 2000

Due to the rapid growth of ship building industry and increment of ship construction in Korea, several hundred thousand of lifting lugs per year, have been installed at the lifting positions of ship block and removed after finishing their function, therefore, appropriate design system for strength check or optimal design of each lug structure has been required in order to increase the capability of efficient design. In this study, design system of D-type lifting lug structure which is most popular and useful in shipyards, was developed for the purpose of initial design of lug structure. Developed system layout and graphic user interface for this design system based on the C++ language were explained step by step. Using this design system, more efficient performance of lug structural design will be expected on the windows of personal computer.

• Journal of the Society of Naval Architects of Korea
• /
• v.52 no.6
• /
• pp.444-451
• /
• 2015

Lifting lugs are frequently used in shipyard to transport and turn over blocks of ship and offshore structures. As the shipbuilding technology develops, blocks has become bigger and bigger, and block management technology takes a more important role in shipbuilding to enhance the productivity. For the sake of economic as well as safe design of lug structure, more rational design procedure based on the rigorous structural analysis is needed. This study is concerned with the optimum design of T type lug which is frequently used in shipyard. The optimum thickness of lug's main body is to be determined based on the results of non-linear strength analysis. As far as the present results for the present T type lugs having different capacity are concerned, it seems to be necessary to review the current design procedure of lug structure. The present design procedure can be extensively used in design of various types of lug structures used in shipyard.

• Journal of Ocean Engineering and Technology
• /
• v.25 no.2
• /
• pp.101-107
• /
• 2011

In view of the importance of material reduction because of the jump in oil and steel prices, structural design studies for lifting lugs were performed. Hundreds of thousands of such lifting lug structures are needed every year for ship construction. A direct design study was reviewed using the developed design system to increase the design efficiency and provide a way of directly inserting a designer's decisions into the design system process. In order to understand the design efficiency and convenience of a lug structure, parametric studies for prototype lug shapes were performed using the developed design system. From these design studies, various patterns of design parameters for the lug structure according to changes in the main plate length were examined. Based on these parametric study results, design guides were developed for more efficiently suggesting structural data for enormous lug structures. Additionally, a more detailed structural analysis through local strength evaluations will be performed to verify the efficiency of the optimum structural design for a lug structure.

• Special Issue of the Society of Naval Architects of Korea
• /
• 2011.09a
• /
• pp.82-89
• /
• 2011

In general, a number of lifting lugs have been used in shipbuilding industry and the D-type lugs are mainly used. The aim of this paper is to increase the cycle of the use and to reduce the size of lifting lugs to introduce lightweight shackle. In this study, nonlinear elasto-plastic analysis has been performed to confirm the ultimate strength of lifting lugs. In order to evaluate the proper design-load distribution around lug eye, the contact force between lifting lug and shackle pin has been realized by gab element model. Gap element modeling and nonlinear analysis are carried out using the finite element program MSC/PATRAN & ABQUS. Additionally the ultimate strength tests were performed to verify the structural adequacy of newly designed lifting lug and to insure safety of it. The D-10, 15, 20 & 40 ton models which are mainly used in the block erection are selected in the strength test. According to the results of the analysis and strength test, the ultimate strength of the newly designed lifting lugs has been estimated to exceed 3 times of design working load.

• Journal of Ocean Engineering and Technology
• /
• v.23 no.2
• /
• pp.104-109
• /
• 2009

In the view of the importance of material reduction due to the jump in oil and steel prices, an optimized structural system for lifting lugs was developed. Such a system is needed hundreds of thousands of times a year. A direct design process was added to this developed optimized system to increase the design efficiency and provide a way of directly inserting a designer's decisions into the design system process. In order to verify the system efficiency and convenience, several new prototype lug shapes were suggested using the developed system. From these research results, it was found that the slope of the main plate of the lug structure has a tendency to move from about 45 degrees to about 60 degrees and the design weight was reduced from an initial value of about 32kgf to about $15{\sim}19kg_f$ after the redesign. Based on these initial research results, an efficient reduction in steel weight was expected considering the enormous consumption of lug structures per year. Additionally, a more detail structural analysis through local strength evaluations will be performed to verify the efficiency of the optimum structural design for a lug structure.

• Journal of Ocean Engineering and Technology
• /
• v.11 no.4
• /
• pp.249-261
• /
• 1997

A basic study on the lifting lug design has performed through the rational and systematic process. In order to evaluate the proper design-load distribution around lug eye investigation of contact force between lifting lug and shackle pin is performed using non-linear parametric analysis idealized by gap element models. Gap element modeling and nonlinear analysis procedures are illustrated and discussed based on MSC/NASTRAN. Some analysis and design guides are suggested through the consideration of several important effects such as stress distribution pattern, circumferential contact force distribution along the lug eye face, loading share rate between lug main plate and doubler, effect of loading direction, relation between applied force and deflection and size effect of shackle pin radius. Additionally optimum design studies are performed and general trends according to the variation of design parameters are suggested.

• Journal of Ocean Engineering and Technology
• /
• v.29 no.4
• /
• pp.309-316
• /
• 2015

Lifting lugs are frequently used in shipyards to transport and turn over the blocks of ships and offshore structures. With the development of shipbuilding technology, blocks have increased in size, and block management technology has assumed a more important role in shipbuilding to enhance the productivity. For the sake of economics, as well as the safe design of a lug structure, a more rational design procedure based on a rigorous structural analysis is needed. This study investigated the strength characteristics of T-type lugs, considering the influence of blocks on which lugs are attached, by varying the in-plane and out-of-plane load direction. In this paper, the ultimate strength is also addressed for cases that include or do not include blocks in the strength analysis. In the present results, when there was a load acting in the normal direction to the block surface, the strength characteristics became poor, and the ultimate strength decreased. This paper ends by describing the need for further study to develop a more rational design for a lug structure.

• Journal of Welding and Joining
• /
• v.30 no.1
• /
• pp.72-77
• /
• 2012

Recently, according to the increase of income and development of quality of life, the leisure industry has been developed. In particular, the interest of design and manufacture technology of leisure yacht has significantly increased. However, domestic market of leisure ships is currently in its initiating stage. So research and development for structural strength of leisure yacht need to be investigated. In this study, lug of yacht's mast which is known for a critical damage region is explicitly considered. This paper deals with the estimation of stress concentration factors (SCFs) for lug of yacht's mast depending on dimensions of lug using hot spot stress. Also, SCF formulae is suggested using parametric study.

• Special Issue of the Society of Naval Architects of Korea
• /
• 2011.09a
• /
• pp.51-54
• /
• 2011

This paper presents methods for design and strength analysis of lifting lugs utilized in assembling, erection, and turning over of ship structures. Lifting lugs are designed in accordance with ASME BTH-1-2008; Design of Below-the-Hook Lifting Devices. Experimental tests for fillet welded joints were conducted to design weld size of lifting lugs and under-structures. The nonlinear finite element method, using MSC.Marc software, is employed for limit state assessment of lifting lugs in static loading conditions. The analysis considers nonlinearities in material properties and contact between lifting lug and pin.