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고강도 알루미늄 7175 합금 링롤재의 급냉 및 응력제거처리후 잔류응력 유한요소해석 및 측정

  • 박성한;구송회;이방업;은일상
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • pp.181-187
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    • 1997
  • 고강도 알루미늄 합금 링롤재의 급냉, 링 팽창(expansion) 및 링 압축(compression) 응력제거처리후 잔류응력을 예측하기 위하여 2차원 축대칭 열해석 및 탄소성 해석을 수행하였다. 급냉 및 응력제거처리 후 2단 과시효 처리(T73)된 링롤재에 대하여 3단계 절단법(Three step sectioning method)을 적용하여 링롤재의 두께에 따른 잔류응력 분포를 측정하였으며, 측정결과를 급냉 및 응력제거처리후 잔류응력 해석결과와 비교분석하였다. 링의 급냉후 원주 및 축방향의 잔류응력 해석값은 T73후 측정값과 비슷한 경향을 보였으며, 링의 내면과 외면에서 압축응력을 나타내었고 중심에서 인장응력을 나타내었다. 잔류응력은 링 팽창(T7351) 및 링 압축(T7352) 적용후 T73에 비해 현저히 감소하였으며, 축방향의 제거 효과가 원주방향보다 우수하게 나타났다. 또한 링 압축에 의한 제거효과가 링 팽창보다 크게 나타났다. 링롤재의 응력제거처리는 제거 효과 및 실용성 측면에서 링 압축 공정이 유리하며, 치수제어 및 장비용량 측면에서 링 팽창 공정이 유리하다는 결론을 얻었다.

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Analysis and Measurement of Residual Stress of Al 7175 Ring Rolls after Quenching and stress Relieving (고강도 알루미늄 7175 합금 링롤재의 급냉 및 응력제거처리후 잔류응력 유한요소해석 및 측정)

  • 박성한;구송회;이방업;은일상
    • Journal of the Korean Society of Propulsion Engineers
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    • v.1 no.1
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    • pp.104-110
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    • 1997
  • To predict the effect of ring expansion and ring compression on residual stress relief of Al 7175 ring rot]s, 2-D axisymmetric thermal analysis and elastoplastic analysis were performed. The residual stress distributions along the thickness of T73, T7351 and T7352 treated rings were measured using three step sectioning method. The measured results were compared to numerical ones for quenched and stress relieved rings. After quenching, calculated hoop and axial residual stresses were similar to measured ones for T73 treated rings. The residual stresses of T7351 and T7352 treated rings were decreased remarkably compared to T73 treated rings. The effect of axial residual stress relief was superior to that of hoop one, and also ring compression to ring expansion. It was concluded that ring compression is advantageous over ring expansion in view of stress relief effect and practicality, and vice versa in view of dimensional control and press power.

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Development of Stress Indices for Trunnion Pipe Support (원통형 배관 지지대의 응력계수 개발)

  • 김종민;박명규;엄세윤;이대희;박준수
    • Computational Structural Engineering
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    • v.9 no.3
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    • pp.115-123
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    • 1996
  • A finite element analysis of a trunnion pipe anchor is presented. The structure is analyzed for the case of internal pressure and moment loadings. The stress results are categorized into the average (membrance) and the linearly varying(bending) stresses through the thickness. The resulting stresses are interpreted per Section III of the ASME Boiler and Pressure Vessel Code from which the Primary (B/sub 1/) and Secondary(C/sub 1/) stress indices for pressure, the Primary(B/sub 2R/, B/sub 2T/) and Secondary(C/sub 2R/, C/sub 2T/) stress indices for moment are developed. Several analyses were performed for various structural geometries in order to obtain empirical representation for the stress indices in terms of dimensionless ratios.

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A photoelastic study of the stress distribution on canine retraction by segmented TMA T-loop spring (Segmented TMA T-loop spring에 의한 견치 후방이동시의 응력분포에 관한 광탄성법적 분석)

  • Yoon, Young-Jooh;Kim, Kwang-Won;Yu, Pil-Sik
    • The korean journal of orthodontics
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    • v.31 no.2
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    • pp.199-207
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    • 2001
  • The segmented TMA T-loop spring, used for reciprocal space closure and described by Burstone, was used to achievebodily movement of canine. Photoelastic analysis is a technique for the transformation of internal stress into visible light patterns. The two-dimensional photoelastic stress analysis was performed, and stress distribution was recorded by photography. The purpose of this study was to visualize photoelastically the distribution of forces transmitted to the alveolus and surrounding structures using new segmented TMA T-loop spring for canine retraction. The results were as follows: 1. Decreased activation produced decreased stress of upper 1st. premolar extraction site and increased intrusive stress of upper 1st. molar, regardless of T-loop position. 2. At 5mm activation, More posterior positioning of T-loop Produced an increased stress in upper 1st. premolar extraction site. 3. At 3mm activation, More posterior positioning of T-loop produced an increased stress in upper 1st. premolar extraction site and mesial lower half of upper 1st. molar mesio-buccal root. 4. At 1mm activation, More anterior positioning of T-loop produced an increased stress in upper mesial and blew apex area of upper canine root. 5. 0.25 B/L ratio and 3mm activation produced bodily movement of canine. To summarize, desired tooth movement and anchorage requirement is possible by altering the activation and mesio-distal position of the T-loop spring.

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A Linearization Model of the Stress Relaxation Curves for Fruits and Vegetables (과일 및 채소의 응력완화 직선화 모델)

  • Yoo, Myung-Shik;Song, Woo-Jin;Rho, Young-Ta;Pyun, Yu-Ryang
    • Korean Journal of Food Science and Technology
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    • v.24 no.3
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    • pp.226-231
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    • 1992
  • A generalized linearization model for stress relaxation curves of vegetative tissues was proposed as $[F_{(o)}t^n/(F_{(o)}-F_{(t)})=k_1+k_2t]$, taking into account internal structure changes under a constant strain. Where $F_{(o)}$ is the initial force, $F_{(t)}$ is the decaying force after time t, and $k_1$, $k_2$ and n are constants. This model was well fit to stress relaxation curves of a variety of raw and processed fruits and vegetables.

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Iodine Stress Corrosion Cracking of Zircaloy-4 Tubes

  • Moon, Kyung-Jin;Lee, Byung-Ho
    • Nuclear Engineering and Technology
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    • v.10 no.2
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    • pp.65-72
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    • 1978
  • In this paper, it is attempted to investigate the phenomena of iodine stress corrosion cracking of Zircaloy-4 cladding failures in reactor through the results of similar out-of-pile test in iodine vapour. The main result of this experiment is a finding of the relation between the threshold stress which can lead to iodine stress corrosion cracking of Zircaloy-4 tube and the iodine concentration. The values of critical stress and the critical iodine concentration are also obtained. A model which relates failure time of Zircaley-4 tube to failure stress and iodine concentration is suggested as follows: log t$_{F}$ =5.5-(3/2)log$_{c}$-4log $\sigma$ where t$_{F}$ : failure time, minutes c: iodne concentration, mg/㎤ $\sigma$: stress, 10$^4$psi.

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3D Semi-elliptical Interfacial Crack Front Stress Fields in Welded Joints (용접부 3차원 반타원 계면균열선단에서의 응력장)

  • 최호승;이형일;송원근
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.15 no.4
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    • pp.649-659
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    • 2002
  • For a variety of elastic-plastic stress fields of plane strain specimens, many research works verified the validity of J-T approach. To generalize the validity of J-T method, however, further investigations are needed for more practical 3D structures than the idealized geometries as plane strain specimens. In this work, selecting two main types of structures such as plate and straight pipe, we perform 3D finite element(FE) modeling, and accompanying elastic, elastic-plastic FE analyses. We then study the validity of J-T application to 3D structures, and present some useful informations for the design or assessment of pipe welds by comparing the stress fields from the detailed 3D FE analyses to those predicted with J-T two parameters.

Non-linear Analysis of Full Scaled CFT Column to H-Beam Connections with T-Stiffeners (T 스티프너를 이용한 CFT기둥-H 형강보 실대형 접합부의 비선형 해석)

  • Lee, Seung Woo;Kim, Young Joo;Shin, Kyung Jae;Oh, Young Suk;Moon, Tae Sup
    • Journal of Korean Society of Steel Construction
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    • v.14 no.6
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    • pp.835-843
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    • 2002
  • The goal of this paper is to understand the stress-transfer mechanism of concrete-filled tubular column to H-beam connection with external T stiffener through the elasto-plastic finite element method and to offer basic data for the design of T stiffener. For the accuracy, analysis results are compared with experimental results. It makes use of several stress and strain indices to understand the stress-transfer mechanism of connection. An alternative plan that decreases the stress concentration of beam flange to horizontal stiffener connection is proposed through the elasto-plastic finite element method.

Evaluation of Stress Intensity Factors and T-Stress Using a Conservation Integral (보존적분을 이용한 응력강도계수와 T-응력의 계산)

  • 범현규;엄윤용
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.1
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    • pp.121-126
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    • 1994
  • A mutual integral, which has the conservation property, is applied to the problem of a crack in an isotropic elastic material. The stress intensity factors $K_{I}, K_{II}, K_{III}$ and T-stress for the problem in an infinite medium are easily obtained by using the mutual integral without solving the boundary value problem. The auxiliary solutions necessary in the proposed method are taken from the known asymptotic solutions. This method is amenable to numerical evaluation of the stress intensity factors and T-stress if the crack in a finite medium is considered.

Estimation of C(t)-Integral in Transient Creep Condition for Pipe with Crack Under Combined Mechanical and Thermal Stress (II) - Elastic-Plastic-Creep - (복합응력이 작용하는 균열 배관에 대한 천이 크리프 조건에서의 C(t)-적분 예측 (II) - 탄-소성-크리프 -)

  • Song, Tae-Kwang;Kim, Yun-Jae
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.33 no.10
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    • pp.1065-1073
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    • 2009
  • In this paper, the estimation method of C(t)-integral for combined mechanical and thermal loads is proposed for elastic-plastic-creep material via 3-dimensional FE analyses. Plasticity induced by initial loading makes relaxation rate different from those produced elastically. Moreover, the interactions between mechanical and thermal loads make the relaxation rate different from those produced under mechanical load alone. To quantify C(t)-integral for combined mechanical and thermal loads, the simplified formula are developed by modifying redistribution time in existing work done by Ainsworth et al..