• Title/Summary/Keyword: multiaxial stress

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Analysis on Creep of Concrete under Multiaxial Stresses Using Microplane Model (미세평면 모델을 적용한 다축응력 상태의 콘크리트 크리프 분석)

  • Kwon Seung-Hee;Kim Yun-Yong;Kim Jin-Keun
    • Journal of the Korea Concrete Institute
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    • v.16 no.2 s.80
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    • pp.195-204
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    • 2004
  • Poisson's ratio due to multiaxial creep of concrete reported by existing experimental works was controversial. Poisson's ratio calculated from measured strain is very sensitive to small experimental error. This sensitivity make it difficult to find out whether the Poisson's ratio varies with time or remain constant, and whether the Poisson's ratio has different value with stress states or not. A new approach method is needed to resolve the discrepancy and obtain reliable results. This paper presents analytical study on multiaxial creep test results. Microplane model as a new approach method is applied to optimally fitting the test data extracted from experimental studies on multiaxial creep of concrete. Double-power law is used as a model to present volumetric and deviatoric creep evolutions on a microplane. Six parameters representing the volumetric and deviatoric compliance functions are determined from regression analysis and the optimum fits accurately describe the test data. Poisson's ratio is calculated from the optimum fits and its value varies with time. Regression analysis is also performed assuming that Poisson's ratio remains constant with time. Four parameters are determined for this condition, and the error between the optimum fits and the test data is slightly larger than that for six parameter regression results. The constant Poisson's ratio with time is obtained from four parameter analysis results and the constant value can be used in practice without serious error.

Stress Analysis of MWK Composite Laminate with Multi-pin Loaded Holes (다중 핀 하중을 받는 MWK 복합재료의 응력 해석)

  • 조민규;김병구;전흥재;변준형
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2003.04a
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    • pp.74-78
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    • 2003
  • Stress analysis was conducted with finite element method to study the stress distributions in both single-pin and multi-pin loaded composite laminates. The various parameters involved in the design of the joint method were considered. The stress distributions in the vicinity of the holes were predicted considering the effects of various parameters such as the lay-ups, number of pins, number of rows, row spacing, and hole patterns. The results show that the performance of joint is greatly affected by these parameters.

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Dynamic Stress/Strain Measurement and Analysis of the Aluminum Alloy Road Wheel through F1 Circuit Ultimate Driving Test (F1 서킷 극한주행시험을 통한 알루미늄 알로이 휠의 동응력/변형률 계측 및 분석)

  • Lee, Chang Soo;Park, Cheol Soon;Park, Hyung Bae;Jung, Sung Pil;Chung, Won Sun
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2014.10a
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    • pp.612-617
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    • 2014
  • It is generally known that the automotive road wheel involves the non-proportional multiaxial loading condition, therefore the measuring dynamic stress and strain in driving state is very important to predict an endurance characteristic of the automotive road wheel. In this study, the ultimate driving test using F1 circuit with respect to 2 kinds of velocity conditions have been carried out in order to measure dynamic stress, strain of the wheel and acceleration of a vehicle. Based on the measured results, the characteristics of dynamic stress generation have been analyzed, and factors which have effect on the dynamic stress generation have been studied.

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Material Model and Thermal Response Analysis of Concrete at Elevated Temperatures (고온에서의 콘크리트 재료모델과 열거동해석)

  • 강석원;홍성걸
    • Journal of the Korea Concrete Institute
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    • v.13 no.3
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    • pp.268-276
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    • 2001
  • A numerical model for the thermal response analysis of concrete structures is suggested. The model includes the stress-strain relationship, constitutive relationship, and multiaxial failure criteria at elevated temperature conditions. Modified Saenz's model was used to describe the stress-strain relationship at high temperatures. Concrete subjected to elevated temperatures undergoes rapid strain increase and dimensional instability. In order to explain those changes in mechanical properties, a constitutive model of concrete subjected to elevated temperature is proposed. The model consists of four strain components; free thermal creep strain, stress-induced (mechanical) strain, thermal creep strain, and transient strain due to moisture effects. The failure model employs modified Drucker-Prager model in order to describe the temperature dependent multiaxial failure criteria. Some numerical analyses are performed and compared with the experimental results to verify the proposed model. According to the comparison, the suggested material model gives reliable analytical results.

Contact Fatigue Life Prediction under Elliptical Elastohydrodynamic Lubrication (타원접촉 EHL 상태에서의 접촉피로수명 예측)

  • Kim, Tae-Wan;Lee, Sang-Don;Koo, Young-Pil;Cho, Yang-Joo
    • Tribology and Lubricants
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    • v.22 no.6
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    • pp.320-328
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    • 2006
  • In this study, the simulation of rolling contact fatigue based on stress analysis is conducted under Elastohydrodynamic Lubrication state. To predict a crack initiation life accurately, it is necessary to calculate contact stress and subsurface stresses accurately. Contact stresses are obtained by contact analysis of a semi-infinile solid based on the use of influence functions and the subsurface stress field is obtained using rectangular patch solutions. And a numerical algorithm using Newton-Rapson method was constructed to calculate the Elastohydrodynamic lubrication pressure. Based on these stress values, several multiaxial high-cycle fatigue criteria are used and the critical loads corresponding to fatigue limits are calculated.

A Study on the Fatigue Crack Propagation Behavior of Spot Welds under Tensile-shear Load (인장-전단 하중을 받는 점용접부의 피로균열 전파거동에 관한 연구)

  • 이용복
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.6 no.4
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    • pp.27-33
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    • 1997
  • Spot welding has been used in the sheet metal jointing processes because of its high productivity and convenience. In this study, effects of welding conditions on the fatigue life and prediction methods of fatigue life of spot welded joint have been studded . Fatigue life was estimated by stress index parameter considering multiaxial stresses. Fatigue tests were conducted with the tensile-shear specimens using SPCC. Fatigue life of spot welded joint was influenced by welding currents and was predicted exactly with taking into account StageIII.

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Fatigue Life Prediction of Spot Welds in SPCC (냉간압연강판 점용접부의 피로수명예측)

  • 이용복
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 1997.04a
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    • pp.137-142
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    • 1997
  • Spot welding has been used in the sheet metal joining processes because of its high productivity and convenience. In this study effects of welding conditions on the fatigue life and predicting methods of fatigue life of spot welded joint have been studied. Fatigue life was estimated by stress index parameter considering multiaxial stresses. Fatigue tests were conducted with the tensile-shear specimens using SPCC. Fatigue life of spot welded joint was influenced by welding currents and was predicted exactly with taking into account Stage III.

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Fatigue Life Prediction of Spot Welds under Tensile-Bending Load (인장-굽힘을 받는 점용접부의 피로수명예측)

  • 이용복;조주환;정진성;조현억
    • Proceedings of the KWS Conference
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    • 1997.10a
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    • pp.77-80
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    • 1997
  • Spot welding has been used in the sheet metal joining processes because of its high productivity and convenience. In this study, predicting methods of fatigue life of spot welded joint have been studied fatigue life of conch-peel spot welded joint was influenced by tail effect. Fatigue life was estimated by stress index parameter considering multiaxial stresses and tail effect. Fatigue tests were conducted with the coach-peel specimens using SPCC.

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Stress Analysis of Mechanically Fastened Joints in MWK Composite Laminate with Different Geometric :Factors and Loading Conditions (다축경편 복합재료 평판의 기계적 체결시 기하학적 형상 및 하중조건에 다른 응력해석)

  • Choi J.-M.;Jo M.-G.;Chun H.-J.;Byun J.-H.
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2004.04a
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    • pp.246-249
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    • 2004
  • When MWK (Multiaxial Warp Knitted Fabric) composites are applied for the structures, the connections of each component using mechanical fastening is needed. The local contact between the bolted joint and the composite laminates may induce high stress concentration or breakdown in the laminates for the mechanical joints. There for, it is strongly required to study the characteristics of mechanically joints of MWK composite laminates. In this study, stress analysis near the hole boundary of MWK composite laminate is conducted with various geometric factors under different loadings. In the case of multi-pin loaded MWK composite laminates, the results show that the types of loadings and geometric factors of mechanical joints have a significant influence on the joint performances.

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A comprehensive description for damage of concrete subjected to complex loading

  • Meyer, Christian;Peng, Xianghe
    • Structural Engineering and Mechanics
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    • v.5 no.6
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    • pp.679-689
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    • 1997
  • The damage of concrete subjected to multiaxial complex loading involves strong anisotropy due to its highly heterogeneous nature and the geometrically anisotropic characteristic of the microcracks. A comprehensive description of concrete damage is proposed by introducing a fourth-order anisotropic damage tenser. The evolution of damage is assumed to be related to the principal components of the current states of stress and damage. The unilateral effect of damage due to the closure and opening of microcracks is taken into account by introducing projection tensors that are also determined by the current state of stress. The proposed damage model considers the different kinds of damage mechanisms that result in different failure modes and different patterns of microdefects that cause different unilateral effects. This damage model is embedded in a thermomechanically consistent constitutive equation in which hardening and the triaxial compression caused shear-enhanced compaction can also be taken into account. The validity of the proposed model is verified by comparing theoretical and experimental results of plain and steel fiber reinforced concrete subjected to complex triaxial stress histories.