• Title/Summary/Keyword: Deformation Tube

검색결과 388건 처리시간 0.021초

유한요소법을 적용한 하이드로포밍 공정 해석 및 성형한계 예측 (Analysis of Hydroforming Process and Forming Limit Prediction by FEM)

  • 김정;강성종;강범수
    • 한국소성가공학회:학술대회논문집
    • /
    • 한국소성가공학회 2001년도 춘계학술대회 논문집
    • /
    • pp.36-39
    • /
    • 2001
  • Tubular hydroforming has attracted increased attention in the automotive industry recently. In this study, a professional finite element program for analysis and design of tube hydroforming processes has been developed, called HydroFORM-3D, which is based on a rigid-plastic model. With the developed program several hydroforming processes such as a tee extrusion, an automotive rear axle housing and lower arm are analyzed and designed. And also, the Oyane's ductile fracture integral I was calculated from the histories of stress and strain according to every element and then the forming limit of the hydroforming process could be evaluated. The pediction of the bursting failure and the plastic deformation during typical hydroforming processes shows to be reasonable so that this approach can be extended to other various tube hydroforming processes.

  • PDF

Simplified Algorithm of the Novel Steel-concrete Mixed Structure under Lateral Load

  • Li, Liang;Li, Guo-qiang;Liu, Yu-shu
    • 국제초고층학회논문집
    • /
    • 제1권4호
    • /
    • pp.247-254
    • /
    • 2012
  • In order to improve the seismic behaviors of traditional steel-concrete mixed structure, a novel steel concrete mixed structure consisting of steel frames braced with buckling restrained braces (BRBs) and a concrete tube is proposed. Based on several assumptions, the simplified mechanical model of the novel mixed structure is established, and the shear and bending stiffness formulas of the steel frames, BRBs and concrete tube are respectively introduced. The equilibrium differential equation of the novel mixed structure under horizontal load is developed based on the structural elastic theory. The simplified algorithms to determine the lateral displacement and internal forces of the novel mixed structure under the inverted-triangle distributed load, uniformly load and top-concentrated load are then obtained considering several boundary conditions and compatible deformation conditions. The effectiveness of the simplified algorithms is verified by FEM comparison.

다중스케일 기법을 이용한 카본나노튜브 복합재료의 물성치 계산 (Estimation of material properties of carbon nanotube composite applying multi-scale method)

  • 김정택;현석정;김철
    • 한국복합재료학회:학술대회논문집
    • /
    • 한국복합재료학회 2004년도 춘계학술발표대회 논문집
    • /
    • pp.165-168
    • /
    • 2004
  • Carbon nanotube is a geometrical frame-like structure and the primary bonds between two nearest-neighboring atoms act like beam members, whereas an individual atom acts as the joint of the related beam members. The sectional property parameters of these beam members are obtained from molecular mechanics. Computations of the elastic deformation of single-walled carbon nanotubes reveal that the Young's moduli of carbon nanotubes vary with the tube diameter and are affected by their helicity. With increasing tube diameter, the Young's moduli of carbon nanotubes approach the Young's modulus of graphite.

  • PDF

Utilization improvement of PDMS and fluoropolymers by mutual application

  • Sihn, Youngho;Lee, Woojin
    • Membrane and Water Treatment
    • /
    • 제2권1호
    • /
    • pp.39-49
    • /
    • 2011
  • We investigated about the utilization improvement of the PDMS and fluoropolymers by mutual application in environmental analysis. We were conducted the direct fluorination with mild condition on the PDMS films and analyzed its surfaces before and after fluorination. The results of FTIR and SEM analysis on the PDMS films showed that the film surfaces were fluorinated without irreversible deformation by the fluorination. During the fluorination, the measured contact angles of water and several alcohols on the PDMS films decreased with time and that of most alcohols decreased to 0 after 30 minutes. The surface energy of fluorinated PDMS films has increased by 2 times. Also, we investigated the influence factors on the change of permeation rate of water through PDMS tubes with time. It was observed that the change of permeation rate of water through PDMS tube was affected by temperature, water phase and spatial distribution of water. From these results, we could verify the principal causes of the decrease of permeation rate of water through PDMS tube with time and proposed a new experimental setup for reducing the variation of permeation rate of water less than 2%.

하이드로 임베딩시 체결용 연결요소의 형상 최적화 연구 (Studies on the Shape Optimization of Connecting Element for Hydro-Embedding)

  • 김봉준;김동규;김동진;문영훈
    • 소성∙가공
    • /
    • 제14권9호통권81호
    • /
    • pp.756-763
    • /
    • 2005
  • The applicability and productivity of hydroforming process can be increased by combining pre- and post-forming processes such as the bending, piercing and embedding process. For the fabrication of automotive parts, the hollow bodies with connecting nuts are widely used to connect parts together. Hollow body with connecting nuts has been conventionally fabricated by welding nuts or screwing in autobody screws. It requires multiple steps and devices fur the welding and/or screwing Therefore in this study, hydro-embedding process that combines the hydraulic embedding of connecting element(nut) with hydroforming process is investigated. Studies on the hydro-embedding technology have been performed to optimize the shape of the connecting element by analyzing the deformed mode of the embedded tube The effects of the shape of the screw tip, screw thread and shape of thread on the connection force between the tube and the connecting element have been investigated to optimize the shape of connecting element. Finite element analysis has also been performed to provide deformation behaviors of the tube surrounding a hole produced by hydro-embedding.

자전거 프레임 튜브 두께에 따른 구조적 내구성 해석 (Structural Durability Analysis According to the Thickness of Bicycle Frame Tube)

  • 조재웅;한문식
    • 한국기계가공학회지
    • /
    • 제11권3호
    • /
    • pp.122-129
    • /
    • 2012
  • This study investigates structural and vibration analyses according to the thickness of bicycle frame tube. The model of bicycle frame has the dimension as length of 862mm, width of 100mm and hight of 402.5mm. There are 3 kinds of models with tubes of top, down and seat at bicycle frame as thicknesses of 10, 15 and 20mm. The maximum displacement and stress occur at the center part of seat stay and at the installation part of rear wheel respectively. Maximum displacements become 0.031936, 0.029159 and 0.027984mm in cases of thicknesses of 10, 15 and 20mm respectively. In case of thickness of 20mm among 3 cases, maximum displacement becomes lowest. But maximum stresses become 10.019, 8.5492 and 9.2511MPa in cases of thicknesses of 10, 15 and 20mm respectively. In case of thickness of 15mm among 3 cases, maximum stress becomes lowest. There is no resonance at practical driving conditions and natural frequency remains almost unchanged along the change of thickness. In case of the displacement due to vibration mode, the displacement difference at thickness between 15mm and 20mm becomes 1/2 times than that between 10mm and 15mm. Design at bicycle frame tube becomes most economical and durable effectively in case of thickness of 15mm among 3 cases.

Behavior and design of stainless steel tubular member welded end connections

  • Kiymaz, Guven;Seckin, Edip
    • Steel and Composite Structures
    • /
    • 제17권3호
    • /
    • pp.253-269
    • /
    • 2014
  • Among the various alternatives to make a steel tubular member connection, making a slotted and gusset plate welded connection is one of the most frequently preferred alternatives. This type of connection is essentially an end connection that is made by slotting the tube longitudinally, inserting the gusset plate and then placing longitudinal fillet welds at the tube-to-plate interface. In this paper an experimental study on the behaviour of such connections in stainless steel is presented. 24 specimens were tested under concentrically applied axial tensile forces for varying tube-to-gusset plate weld lengths. Both circular and box section members were considered in the test program. Load-deformation curves were obtained and comparisons were made in terms of strength and ductility. The results obtained from the study were then critically examined and compared with currently available design guidance for slotted gusset plate welded tubular end connections. It is noted that no specific rules exist in international specifications on structural stainless steel which cover the design of such connections. Therefore, the results of this study are compared with the existing design rules for carbon steel.

ACOUSTIC EMISSION CHARACTERISTICS OF STRESS CORROSION CRACKS IN A TYPE 304 STAINLESS STEEL TUBE

  • HWANG, WOONGGI;BAE, SEUNGGI;KIM, JAESEONG;KANG, SUNGSIK;KWAG, NOGWON;LEE, BOYOUNG
    • Nuclear Engineering and Technology
    • /
    • 제47권4호
    • /
    • pp.454-460
    • /
    • 2015
  • Acoustic emission (AE) is one of the promising methods for detecting the formation of stress corrosion cracks (SCCs) in laboratory tests. This method has the advantage of online inspection. Some studies have been conducted to investigate the characteristics of AE parameters during SCC propagation. However, it is difficult to classify the distinct features of SCC behavior. Because the previous studies were performed on slow strain rate test or compact tension specimens, it is difficult to make certain correlations between AE signals and actual SCC behavior in real tube-type specimens. In this study, the specimen was a AISI 304 stainless steel tube widely applied in the nuclear industry, and an accelerated test was conducted at high temperature and pressure with a corrosive environmental condition. The study result indicated that intense AE signals were mainly detected in the elastic deformation region, and a good correlation was observed between AE activity and crack growth. By contrast, the behavior of accumulated counts was divided into four regions. According to the waveform analysis, a specific waveform pattern was observed during SCC development. It is suggested that AE can be used to detect and monitor SCC initiation and propagation in actual tubes.

박격포 포신 제작을 위한 Inconel718 소재의 전진 유동성형 조건 선정에 관한 연구 (A Study on the Selection of Forward Flow Forming Conditions with Inconel718 Tube for Mortar Barrel Manufacturing)

  • 고세권;조영태
    • 한국기계가공학회지
    • /
    • 제18권8호
    • /
    • pp.51-59
    • /
    • 2019
  • Flow forming is an eco-friendly and high-efficiency plastic deformation process with fewer chips during a process which is specifically used to manufacture seamless tubular products like tire wheels, rocket motor cases etc. On the development of mortar barrel using Inconel718 tube, some flow formed products had dimensional errors on their thickness. In this study, our purpose is to optimize the process conditions with the smallest dimensional error. In order to find an optimum process condition, 2D axisymmetric FEM simulation analyses with Taguchi method were conducted. Geometric variables (attack angle, flatting angle, roller nose radius) and operating parameters (depth of forming, feed rate) are considered as control factors. Forward flow forming with single roller was first analyzed to determine the effective factors using AFDEX software and attack angle of the roller was identified as the most influential factor. Also, the nose radius of the rollers was confirmed as a significant factor in multi-rollers flow forming system. The effect of rollers offset values are also studied and finally, we proposed optimal conditions to improve the accuracy of flow forming process with Inconel718 tube for mortar barrel manufacturing.

변형하는 가스 이송관 내에서 전파하는 탄화수소화염의 수치 해석 모델링 (Numerical simulation on propagation of hydrocarbon flame in a deformable tube)

  • 곽민철;여재익
    • 한국추진공학회:학술대회논문집
    • /
    • 한국추진공학회 2012년도 제38회 춘계학술대회논문집
    • /
    • pp.304-308
    • /
    • 2012
  • 본 연구는 에틸렌-공기 혼합물로 채워져 있는 변형 가능한 구리 관에서의 초음속 화염 전파를 수치적으로 살펴보았다. 탄화수소의 화염 전파를 해석하기 위하여 지배방정식으로 Navier-Stokes 방정식과 Arrhenius 형태의 1단계 화학 반응식을 활용하였으며 변형 가능한 관을 해석하기 위하여 Inviscid Euler 방정식을 활용하였다. 또한, 두 물질 간 경계면 추적을 위하여 Level-set 기법을, 경계값 결정을 위하여 ghost fluid 기법을 사용하였다. 이러한 수치적 기법을 바탕으로 관의 변화에 따른 초음속 화염 내 팽창파의 전파 및 그에 따른 간섭 현상을 밀도 및 속도 변화를 통해 확인하였으며 초음속 화염 전파에도 안전성이 확보되는 최소 관 두께를 예측할 수 있는 수치적 기반을 마련하였다.

  • PDF