• Title, Summary, Keyword: 두꺼운 실린더

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Analysis of Apparent Fracture Toughness of a Thick-Walled Cylinder with an FGM Coating at the Inner Surface Containing a Radial Edge Crack (반경방향의 모서리 균열을 갖고 내면이 경사기능재료(FGM)로 코팅된 두꺼운 실린더의 겉보기 파괴인성해석)

  • Afsar, A.M.;Rasel, S.M.;Song, J.I.
    • Composites Research
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    • v.23 no.2
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    • pp.1-9
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    • 2010
  • This study analyzes the apparent fracture toughness of a thick-walled cylinder with a functionally graded material (FGM) coating at the inner surface of the cylinder. The cylinder is assumed to have a single radial edge crack emanating from its inner surface. The crack surfaces and the inner surface of the cylinder are subjected to an internal pressure. The incompatible eigenstrain developed in the cylinder due to nonuniform coefficient of thermal expansion as a result of cooling from sintering temperature is taken into account. Based on a method of evaluating stress intensity factor introduced in our previous study, an approach is developed to calculate apparent fracture toughness. The approach is demonstrated for a cylinder with a TiC/$Al_{2}O_{3}$ FGM coating and some numerical results of apparent fracture toughness are presented graphically. The effects of material distribution profile, cylinder wall thickness, application temperature, and coating thickness on the apparent fracture toughness are investigated in details. It is found that all of these factors play an important role in controlling the apparent fracture toughness of the cylinder.

Determination of Thermal Shock Stress Intensity Factor for Elliptical Crack by Modified Vainshtok Weight Function Method (수정 Vainshtok 가중함수법에 의한 타원균열의 열충격 응력세기계수의 결정)

  • 이강용;김종성
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.2
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    • pp.463-474
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    • 1995
  • Modified Vainshtok weight function method is developed. The thermal shock stress intensity factors for elliptical surface cracks existed in the thin and thick walled cylinders are determined. The present results are compared with previous solutions and shown to be good agreement with them.

A Study on the Forced Fitting Method of Stern Tube Bearing for Propulsion Shafting in Ships (선박 추진축계 선미관 베어링의 강제 압입 피팅 방식에 관한 연구)

  • Cho, Kwon-Hae;Lee, Jae-Hyun;Kim, Yang-Gon
    • Journal of the Korean Society of Marine Engineering
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    • v.34 no.5
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    • pp.653-660
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    • 2010
  • The stern tube bearing is installed to the stern tube and stern boss casting by using the method of the force pressured fitting. The adequate value of the interference between the stern tube bearing and casting should be considered owing to the slip. In this study, to review and compare the fitting force and the contact pressure, the theory of thick walled cylinder is considered to clarify the formula which received from the maker. Also the fitting force and contact pressure are calculated by using the standard value of interference, Young's modulus, Poisson's ratio and friction coefficient.

Viscoplastic Solution of Thick Walled Cylinder Considering Axial Constraint (축방향 경계 조건을 고려한 두꺼운 실린더의 점소성 응력해)

  • Yoon, Sam-Son;Lee, Soon-Bok
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.27 no.9
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    • pp.1555-1561
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    • 2003
  • Finite element analysis using modern constitutive equation is one of the most general tools to simulate the deformation behavior and to predict the life of the structure. Constitutive equation becomes complicated so as to predict the material behavior more accurately than the classical models. Because of the complexity of constitutive model, numerical treatment becomes so difficult that the calculation should be verified carefully. One-element tests, simple tension or simple shear, are usually used to verify the accuracy of finite element analysis using complicated constitutive model. Since this test is mainly focused on the time integration scheme, it is also necessary to verify the equilibrium iteration using material stiffness matrix and to compare FE results with solution of structures. In this investigation, viscoplastic solution of thick walled cylinder was derived considering axial constraints and was compared with the finite element analysis. All the numerical solutions showed a good coincidence with FE results. This numerical solution can be used as a verification tool for newly developed FE code with complicated constitutive model.

A Study on Structural Safety of the Boom Hoisting Cylinder of a Coal Handling Machine (석탄하역기 붐 호이스팅 실린더의 구조 안전성에 관한 연구)

  • Choi, Yong Hoon;Kwak, Hyo Seo;Kim, Chul
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.39 no.12
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    • pp.1265-1273
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    • 2015
  • A coal handling machine is a type of equipment used for loading coal, the main material in a steam power plant, along a conveyer belt from a ship, and is placed after the driving chain bucket. However, studies on the boom hoisting cylinder, which is a hydraulic system used to control the angle of the boom based on loading location, indicate that domestic models are insufficient, and are thereby often substituted with a foreign product. In this study, a technique for analyzing the contact pressure in a thick-walled cylinder was established by comparing the contact pressure, which is calculated theoretically based on the results obtained from FEM simulation, and by checking whether the working oil is leaking from the boom hoisting cylinder using a v-seal. In addition, the driving motion was simulated according to the strokes of the cylinder, and the structural stability was verified under the maximum output conditions.

Continuous Curing and Residual Stresses of Thick Composite Cylinders (두꺼운 복합재료 실린더의 생산 및 열응력 해석)

  • Kim, Cheol
    • Proceedings of the Korean Society For Composite Materials Conference
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    • pp.49-52
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    • 2000
  • A new composite manufacturing technique which combines winding and curing together is studied and analyzed. This method is especially suited to the manufacture of thick composite materials in which thermal spiking is a common problem. An experimental apparatus was designed and built for use with a filament winder to continuously cure a thick composite cylinder. A hoop-wound composite cylinder with 152 mm wall thickness was manufactured and embedded thermocouples and strain gages were monitored throughout the cure process. The experimental data were compared with analytical results.

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A Numerical Analysis of the Behavior of Liquid Film Around a Rotating Cylinder (회전하는 실린더 주변 액막의 거동에 대한 수치해석적 연구)

  • Lee, Sang-Hyuk;Lee, Jung-Hee;Hur, Nahm-Keon;Seo, Young-Jin;Kim, In-Cheol;Lee, Sung-Jin
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.35 no.5
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    • pp.481-486
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    • 2011
  • It is important to predict the behavior of a liquid film around a rotating cylinder in the film coating process of the steel industry. When the cylinder rotates, the behavior of the liquid film on the rotating cylinder surface is influenced by the cylinder diameter, the rotation speed, the gravitational force, and the fluid properties. These parameters determine the liquid film thickness and the rise of the film on the cylinder surface. In the present study, the two-phase interfacial flow of the liquid film on the rotating cylinder were numerically investigated by using a VOF method. For various rotation speeds, cylinder diameters and fluid viscosities, the behavior of liquid film on the rotating cylinder were predicted. Thicker film around the rotating cylinder was observed with an increase in the rotation speed, cylinder diameter, and fluid viscosity. The present results for the film thickness agreed well with available experimental and analytical results.

Nonlinear Buckling Finite Element Analysis to Estimate Collapse Pressure of Thick Cylinder under Hydrostatic Pressure (두꺼운 원통형 내압용기의 붕괴하중 추정을 위한 비선형좌굴 유한요소해석)

  • Lee, Jae-Hwan;Park, Byoungjae;Choi, Hyuek-Jin
    • Journal of Ocean Engineering and Technology
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    • v.33 no.3
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    • pp.272-279
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    • 2019
  • In order to perform a pressure chamber experiment with a circular cylindrical pressure vessel, the dimensions of the cylinder need to be determined in the range of the maximum externally applied pressure of the chamber to create the collapse process. In this study, the collapse load values from published chamber test results, finite element analysis and the theory of thick cylinders were thoroughly compared in a aluminum cylinder. In order to investigate the effect of collapse load according to the ovality during manufacturing, nonlinear buckling analysis was performed and the collapse load according to ovality was compared. Based on the results, the dimensions of the steel cylinder were determined for the future chamber collapse test.

A Study on the Residual Stress Evaluation of Autofrettaged SCM440 High Strength Steel (자긴가공된 SCM440 고강도강의 잔류응력평가에 관한 연구)

  • Kim, Jae-Hoon;Shim, Woo-Sung;Yoon, Young-Kwen;Lee, Young-Shin;Cha, Ki-Up;Hong, Suck-Kyun
    • Journal of the Korean Society of Propulsion Engineers
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    • v.14 no.4
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    • pp.39-45
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    • 2010
  • Thick-walled cylinders, such as a cannon or nuclear reactor, are autofrettaged to induce advantageous residual stresses into pressure vessels and to increase operating pressure and the fatigue lifetimes. As the autofrettage level increases, the magnitude of compressive residual stress at the bore also increases. The purpose of the present paper is to predict the accurate residual stress of SCM440 high strength steel using the Kendall model which was adopted by ASME Code. Hydraulic pressure process was applied in the inner part and thick-walled cylinders were autofrettaged up to 30% overstrain levels. Electro polishing on the surface of autofrettage specimen was performed to get more accurate residual stress. Residual stresses were measured by X-ray diffraction method. The autofrettage surface which was plastically deformed analyzed using a scanning electron microscope(SEM). Although there were some differences in measured residual stress and numerical results, it has a tendency to agree comparatively with each other.

Low-velocity Impact Damage of a Thick Pressure vessel (복합재료 만든 두꺼운 압력용기의 저속충격에 관한 연구)

  • 김형원
    • Proceedings of the Korean Society For Composite Materials Conference
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    • pp.92-97
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    • 2000
  • Low-velocity impact damage of a thick pressure vessel by composite materials was studied using the modified Herzian contact radius theory. Impactors of various masses and various tup shapes were dropped freely in the range of 20m to 200mm height. With acceleration gage and strain gage installed on the impactor, impact force and acceleration and Contact radius were measured. After a test, the samples were radiographed to scan the state of damage. Compared with hemispherical tup of 12.7mm diameter, the contact radius of hemispherical tup of 25.4mm diameter was bigger. And the experimental data and the theoretical data was different due to the mechanical properties difference. The acceleration value was changed linearly according to the height.

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