• Proceedings of the KWS Conference
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• 2005.11a
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• pp.20-22
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• 2005

In this study, deformation of flange of pedestal crane due to Lug welding and lifting. Thermo elasto-plastic analysis was performed using commercial FE code MSC/MARC. The accuracy control of roundness is critical to the final product assembly. Deformation is mainly occurs during Lug welding. So, we determine welding sequence and Lug space in order to reduce deformation. And we also investigate safety of lifting Lug during crane lifting.

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

• International Journal of Naval Architecture and Ocean Engineering
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• v.11 no.2
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• pp.858-864
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• 2019

The increasing demands of lifting lugs can be attributed to the rapid advancement of shipbuilding and offshore-structure production technologies and an exponential increase in the size of the block units of ship structures. Therefore, to ensure safety during the transportation and turnover of large blocks, it is important to determine the structural integrity and position of lifting lugs. However, because the manufacturing cost and availability of lugs are important considerations, low cost and easily obtainable steel compositions of grades different from those of the blocks are often used as alternatives. The purpose of this study is to investigate the effect of a lifting-lug metal on the physical properties of a base metal in a dissimilar welding between the base metal and lifting lug. The effect was evaluated by observing the metal microstructures and determining the hardness and dilution values on the cross-sectional surface of the lifting lug. According to the results of the metal microstructures, impact, hardness, and emission spectrochemical analysis at the surface from where the lug was removed confirmed that the chemical composition of the lifting-lug metal did not influence the physical properties of the base metal.

• Journal of Ocean Engineering and Technology
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• v.11 no.4
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• pp.249-261
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• 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
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• v.25 no.2
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• pp.101-107
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• 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
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• 2011.09a
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• pp.82-89
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• 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 the Society of Naval Architects of Korea
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• v.51 no.1
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• pp.42-50
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• 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.

• Journal of Welding and Joining
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• v.25 no.6
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• pp.44-52
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• 2007

A welding process of a lifting lug for lifting heavy objects is one of the important welding processes directly related to the safety in shipbuilding. Welding a lifting lug is done in the manually and takes about forty minutes. Working environment for the lifting lug welding is very poor due to an radiant heat and a harmful fume. The purpose of this study is to develop methods of multi-pass welding using the lifting lug welding robot system. This study shows robot welding methods to achieve proper corner, straight and connection welding and an effectiveness of application.

• Proceedings of the KWS Conference
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• 1994.05a
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• pp.208-210
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• 1994

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