• Title/Summary/Keyword: D type lug

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The Structural Strength Assesment of Lifting Lug (리프팅 러그의 구조 강도 평가)

  • Heo, Nam-Hak;Lee, Joo-Sung
    • 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.

Development of the Design System for the Lifting Lug Structure (탑재용 러그 구조의 설계 시스템 개발)

  • 함주혁
    • 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.

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Lifting Lug by the Change of form Using Multivariate Functions: An Optimal Design Study (다변수 함수를 이용한 형상 변화에 따른 리프팅 러그의 최적 설계에 관한 연구)

  • Choi, Kyung-Shin;Kim, Ji-Jun;Lee, Ji-Han;Chan, Gwang-Woo
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.20 no.4
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    • pp.31-38
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    • 2021
  • In this paper, we proposed an optimal design for determining the shape of a lifting lug freely by applying a multivariate function to the D-type lug, which is commonly used in shipyards. We derived the optimal aspect ratio of the lug through structural analysis and analyzed the safety and behavior of the lug aspect ratio. As a result, two types of final candidates, both lighter than the existing lug weight, were suitable for the ratio. They were found to have the greatest force at an angle of 45 degrees when a load of 100 tons was imposed. When the horizontal and vertical feature ratio of the lug was 1:3, it showed excellent results in terms of safety rates while maintaining weight reduction and functional aspects.

Development of the Design System for the Lifting Lug Structure (탑재용 러그 구조의 설계 시스템 개발)

  • Juh-Hyeok Ham
    • 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.

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A Study on the Optimization of Lifting Lug for Block Erection (선박 블럭 탑재용 러그 구조 최적화 연구)

  • Min, Dug-Ki;Eum, Sung-Min
    • 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.

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A Study on the Structural Integrity of Lifting Lug without Appendage (부가물이 미부착된 리프팅 러그의 구조 건전성에 관한 연구)

  • Choi, Kyung-Shin;Kim, Ji-Jun;Choi, JeongJu
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.20 no.11
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    • pp.108-114
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    • 2021
  • In this study, a multivariate function was applied to the genetic algorithm for D-type lugs currently used in shipyards to closely analyze the behavioral form of weight loss without double plates. An optimal lifting lug structure design without attachments is proposed. MATLAB R2016a was used to design features by applying multivariate functions to genetic algorithms. Furthermore, the design was achieved by deriving the optimal shapes of lugs using genetic algorithms. The shapes of the designed lugs were validated for structural bonding using the structural analysis program ANSYS 2020 R2, and a robust design of lugs with no appendages was developed.

Development of Cold Forging Process of Hollow-type Wheel Nut Wrench for Commercial Vehicles (상용차용 중공형 휠 너트 렌치의 냉간단조 공정 개발)

  • Kim, H.S.;Youn, J.W.
    • Transactions of Materials Processing
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    • v.21 no.8
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    • pp.493-498
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    • 2012
  • A wheel nut wrench is one of the hand tools used to loosen and tighten lug nuts on automobile wheels and it has generally a solid-type geometry for commercial vehicles. However, the solid-type wheel nut wrenches manufactured by hot forging processes exhibit several drawbacks such as heavy weight and rough surface finish. Thus, many efforts have been devoted to change the part geometry and improve the manufacturing process. For this purpose, the weight of the final product can be reduced drastically using a hollow tube as the initial stock, which can be manufactured by the more economical manufacturing process of cold forging. In this study, the cold forging of a hollow-type wheel nut wrench for commercial vehicles was designed based on the results of fundamental experiments and CAE analyses using the commercial finite element code DEFORM-3D. In addition, cold forging experiments were conducted on a special-purpose forming machine for hollow wheel nut wrenches in order to validate the designed process sequence. As results, it was found that the final products with a weight reduction of 39% and better surface appearance can be manufactured without any defect with the newly designed cold forging process.