• Title/Summary/Keyword: Bend radius

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Development of Failure Pressure Evaluation Model for Internally Well Thinned Piping Components (내부 감육 배관의 손상압력 평가 모델 개발)

  • Na Man-Gyun;Park Chi-Yong;Kim Jin-Weon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.29 no.7 s.238
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    • pp.947-954
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    • 2005
  • The purpose of this study is to develop failure pressure evaluation models, which are applicable to straight pipes and elbows containing an internally wall thinning defect induced by flow-accelerated-corrosion (FAC). In this study, thus, three dimensional finite element (FE) analyses are performed to investigate the dependences of failure pressure of internally wall thinned pipe on the defect shape, the pipe geometry, and the defect location and bend radius of elbow. Also, the existing failure pressure assessment models for externally wall thinned pipes are examined. Based on these, the new models for assessing failure pressure of piping components with an internally wall thinning defect are proposed. Comparison of failure pressure, predicted by proposed models, with FE analysis result shows good agreement regardless of pipe type, defect shape, and defect location and bend radius.

Study on Springback Characteristic of Cold Rolled Steel Sheet (자동차용 냉연 강판의 형상 동결성 연구)

  • 한수식;박기철;남재복
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 1998.06a
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    • pp.17-24
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    • 1998
  • This paper deals with the springback characteristics of cold rolled sheet steel through the use of the V-bending process and U-bending one. The influence of material properties on the springback of forming processes was investigated. In the V-bending process there was an optimum bend radius for each combination of parameters which produced minimal springback. In the U-bending process the blank holder force can control the degree of springback. A high blank holding force resulted in a uniform strain distribution and reduced the level of springback.

An Evaluation of the Effect of Internal Thinning Defect on the Failure Pressure of Elbow (곡관의 손상압력에 미치는 내부 감육결함의 영향 평가)

  • Kim, Jin-Weon;Kim, Tae-Soon;Park, Chi-Yong
    • Journal of the Korean Society of Safety
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    • v.18 no.4
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    • pp.28-34
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    • 2003
  • In the present study, three-dimensional finite element analysis was performed to investigate the effects of internal wall thinning defect on the failure pressure of elbow in the piping system and to develop the failure pressure evaluation model. From the results of finite element analysis, the failure pressure was derived by employing local stress criteria, and the effects of thinning location, bend radius, and defect geometry on the failure pressure of internally wall thinned elbow were investigated. Also, based on these investigations and previous model developed to estimate the failure pressure of elbow with an external pitting defect, the failure pressure evaluation model to be applicable to the elbow containing an internal thinning defect was proposed and compared with the results of finite element analysis. The failure pressure calculated by the model agreed well with the results of finite element analysis.

A study on tube bending for hydoforming (Hydroforming을 위한 Tube benidng에 관한 연구)

  • 이한남
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 1999.03b
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    • pp.35-38
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    • 1999
  • Tube bending is an important factor of the hydroforming processes. The tube must be bent to the approximate centerline of the finished part prior to hydroforming to enable the tube to be placed in the die cavity. This paper presents the simulation results in prebending process by a rotary bending machne and a bend die that is used to form an automotive part a tie bar, Prebending simulation is carried out to obtain the shape change of cross section and thinning in bending process. To avoid occurring wrinkle in compressive zone during bending process a wiper die included,. A parametric study is carried out to obtain the effect of the forming parameters such as a bend radius and tube thickness

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Development of a Geometry PIG for the Inspection of Natural Gas Pipeline and It´s application

  • Kim, Dong-Kyu;Cho, Sung-Ho;Park, Seoung-Soo;Park, Dae-Jin;Koo, Sung-Ja;Yoo, Hui-Ryong;Park, Yong-Woo;Kho, Young-Tai
    • 제어로봇시스템학회:학술대회논문집
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    • 2001.10a
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    • pp.150.4-150
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    • 2001
  • The geometry PIG provides pipeline operators with continuous measurement of pipe centerline coordinates, bend radius, displacement, and bending strain in a single pass through the pipeline. This study introduces the developed geometry PIG(Pipeline Inspection Gauge) which is used for geometry surveys. This tool is equipped with the several sensor systems. The Inertial Navigation System (INS) comprises angle rate gyros and linear accelerometers. The system measures the precise path of the PIG during its traverse of the pipeline. This system is also used to produce a detailed map of the lire, measure curvature. Odometers measure the PIG´s distance moved along the line and instantaneous speed during the PIG run. Caliper sensors measure pipeline ...

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Burst pressure estimation of Alloy 690 axial cracked steam generator U-bend tubes using finite element damage analysis

  • Kim, Ji-Seok;Kim, Yun-Jae;Lee, Myeong-Woo;Jeon, Jun-Young;Kim, Jong-Sung
    • Nuclear Engineering and Technology
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    • v.53 no.2
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    • pp.666-676
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    • 2021
  • This paper presents numerical estimation of burst pressures of axial cracked U-bend tubes, considering the U-bending process analysis. The validity of the FE simulations is confirmed by comparing with published experimental data. From parametric analyses, it is shown that existing EPRI burst pressure estimation equations for straight tubes can be conservatively used to estimate burst pressures of the U-bend tubes. This is due to the increase in yield strength during the U-bending process. The degree of conservatism would decrease with increasing the bend radius and with increasing the crack depth.

A study on the unfolding length of Z-bending machining using thin plate (박판을 이용한 Z-굽힘 가공의 전개 길이에 관한 연구)

  • Park, Yong-Sun;Choi, Kye-Kwang
    • Design & Manufacturing
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    • v.15 no.3
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    • pp.19-25
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    • 2021
  • The bending process of a press die is to bend a flat blank to the required angle. There are V-bending, U-bending, Z-bending, O-bending etc. for bending processing, and the basic principle of calculating the unfolding length of die processing is used as the neutral plane length. Since the constant of the length value of the neutral surface is different depending on the type of bending, it is impossible to accurately calculate it. In particular, Z-bending processing is performed twice, and it is set on the upper and lower surfaces of the blank, and bending processing occurs at the same time as the upward and downward bending, and the elongation of the material occurs and the material increases. It is not possible to check with the calculated value, and it occurs in many cases where the mold is modified after start-up. This study aims to minimize die modification by developing a formula to calculate the development length of Z-bend.

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Variable Optical Fiber Attenuator Using Bending-Sensitive Fiber

  • Lee, Dong-Ho;Kwon, Kwang-Hee;Song, Jae-Won;Park, Jae-hee
    • Journal of the Optical Society of Korea
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    • v.8 no.2
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    • pp.83-89
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    • 2004
  • A variable optical attenuator with a bending-sensitive fiber (BSF) that can be used in optical networks is developed. The refractive index profile of the BSF is divided into four regions which are inner core, center dip of inner core, outer core and clad. The 3-dimensional finite difference beam propagation method (3D FD-BPM) is utilized to find the characteristics of the BSF, so the mode profile of the BSF and optical power attenuation according to the bending are investigated, and the equivalent model of the BSF is made. By using this equivalent model of the BSF, the BSF is fabricated, and the refractive index profile of the BSF is measured, which is similar to refractive index profile of the proposed BSF. The fabricated variable optical fiber attenuator (VOFA) consists of the BSF in a rectangular rubber ring with a fixed bend radius (BR) in a steady state. The VOFA using the proposed BSF was able to attenuate the optical power by more than about -38 ㏈ at certain wavelengths (1540∼1560 nm) based on adjusting the mechanical pressure applied to the upper surface of the rectangular rubber ring with the bent BSF. In addition, the proposed VOFA produced an insertion loss of 0.68 ㏈, polarization dependent loss (PDL) of about 0.5 ㏈, and return loss of less than -60 ㏈.

Flexible and Transparent Plastic Electrodes Composed of Reduced Graphene Oxide/Polyaniline Films for Supercapacitor Application

  • Sarker, Ashis K.;Hong, Jong-Dal
    • Bulletin of the Korean Chemical Society
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    • v.35 no.6
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    • pp.1799-1805
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    • 2014
  • In this article, we described about the preparation and electrochemical properties of a flexible energy storage system based on a plastic polyethylene terephthalate (PET) substrate. The PET treated with UV/ozone was fabricated with multilayer films composed of 30 polyaniline (PANi)/graphene oxide (GO) bilayers using layer-by-layer assembly of positively charged PANi and negatively charged GO. The conversion of GO to the reduced graphene oxide (RGO) in the multilayer film was achieved using hydroiodic acid vapor at $100^{\circ}C$, whereby PANi structure remained nearly unchanged except a little reduction of doping state. Cyclic voltammetry and charge/discharge curves of 30 PANi/RGO bilayers on PET substrate (shorten to PANi-$RGO_{30}$/PET) exhibited an excellent volumetric capacitance, good cycling stability, and rapid charge/discharge rates despite no use of any metal current collectors. The specific capacitance from charge/discharge curve of the PANi-$RGO_{30}$/PET electrode was found to be $529F/cm^3$ at a current density of $3A/cm^3$, which is one of the best values yet achieved among carbon-based materials including conducting polymers. Furthermore, the intrinsic electrical resistance of the PANi-$RGO_{30}$/PET electrodes varied within 20% range during 200 bending cycles at a fixed bend radius of 2.2 mm, indicating the increase in their flexibility by a factor of 225 compared with the ITO/PET electrode.