• Journal of the Society of Naval Architects of Korea
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• v.38 no.1
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• pp.86-98
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• 2001

Due to the rapid growth of ship building industry and the 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 the strength check or the optimal design of each lug structure has been required in order to increase the capability of efficient design. In this study, the 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. Through the illustration of one example of D-type lug designs, the efficiency of this design system was proved. Therefore, more efficient performance of practical lug structural design will be expected on the windows of personal computer using this design system.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.1
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• pp.29-36
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• 2016

Lifting lugs are frequently used to transport and to turn over blocks of ship and offshore structures in a shipyard. As the shipbuilding technology has been developed, 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 economy as well as safety in design of lug structure, needed is a more rational design procedure based on the ultimate strength derived through the rigorous non-linear structural analysis considering both the material and geometric non-linearity. This study is aimed at deriving the optimum design of T type lug structure which is frequently used in a 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 T type lugs having various capacity are concerned, it can be said that the present optimum design result can guarantee both safety and economy. From the fact that any regular trend cannot be found in weight reduction to the capacity of lugs, 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.

• 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.

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

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.714-717
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• 2011

본 논문에서는 선체 블록의 운반 작업 중 발생하는 동적 하중 및 골리앗 크레인의 와이어로프와 선체블록 간의 동적 접촉력을 고려한 최적 러그 배치 시스템을 설계하고, 다물체계 동역학 커널과 외력 계산커널을 개발하였다. 다물체계 동역학 커널은 recursive formulation을 이용하여 운동 방정식을 구성하고, 외력 계산 커널은 비선형 유체정역학적 힘, 선형 유체동역학적 힘, 풍력, 계류력을 계산할 수 있다. 이를 이용해 블록에 작용하는 와이어로프와 블록 간의 간섭과 동적 접촉력을 계산하고, 그 결과를 이용하여 러그가 부착된 블록의 구조 해석을 수행하였다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.5
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• pp.375-380
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• 2012

In this study, dynamic load and dynamic contact force between a building block and wire ropes of a goliath crane are calculated during lifting or turn-over of a building block for the design of an optimal lug arrangement system. In addition, a multibody dynamics kernel for implementing the system were developed. In the multibody dynamics kernel, the equations of motion are constructed using recursive formulation. To evaluate the applicability of the developed kernels, the interferences and dynamic contact force between the building block and wire ropes were calculated and then the hull structural analysis for the block was performed using the calculation result.

• 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.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.4
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• pp.363-371
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• 2023

To construct a ship, blocks of various sizes must be moved and erected . In this process, lugs are used such that they match the block fastening method and various functions suitable for the characteristics of each shipyard facility. The sizes and shapes of the lugs vary depending on the weight and shape of the block structures. The structure is reinforced by welding the doubling pads to compensate for insufficient rigidity around the holes where the shackle is fastened. As for the method of designing lugs according to lifting loading conditions, a simple calculation based on the beam theory and structural analysis using numerical modeling are performed. In the case of the analytical method, a standardized evaluation method must be established because results may differ depending on the type of element and modeling method. The application of this ambiguous methodology may cause serious safety problems during the process of moving and turning-over blocks. In this study , the effects of various parameters are compared and analyzed through numerical structural analysis to determine the modeling conditions and evaluation method that can evaluate the actual structural response of the lug. The modeling technique that represents the plate part and weld bead around the lug hole provides the most realistic behavior results. The modeling results with the same conditions as those of the actual lug where only the weld bead is connected to the main body of the lug, showed a lower ulimated strength compared with the results obtained by applying the MPC load. The two-dimensional shell element is applied to reduce the modeling and analysis time, and a safety working load was verified to be predicted by reducing the thickness of the doubling pad by 85%. The results of the effects of various parameters reviewed in the study are expected to be used as good reference data for the lug design and safe working load prediction.

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