• Title/Summary/Keyword: Strain Prediction

Search Result 854, Processing Time 0.023 seconds

Creep Life Prediction by ISM of Elevated Temperature Materials for Pressure Vessel(II) (압력용기용 고온재료의 ISM에 의한 크리프 수명예측(II))

  • 공유식;김헌경;황성필;김일석;오세규
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
    • /
    • 2001.05a
    • /
    • pp.307-313
    • /
    • 2001
  • In this Paper, friction welding optimization for 1Cr0.5Mo-STS304($\Phi$14mm), AE applications for the weld quality evaluation and the applications of various life prediction methods such as LMP(Larson-Miller Parameter) and ISM(initial strain method) were investigated : the creep behaviors of those steels and the friction welded joints under static load were examined by ISM combined with LMP at 400, 500, 550 and $600^{\circ}C$, and the relationship between these two kinds of phenomena was studied. The real-time predicting equations of elevated-temperature creep life(fracture time) under any creep stress at any elevated- temperature could be developed by LMP and LMP-ISM, It was confirmed that the life prediction equations by LMP and LMP-ISM are effective only up to 10$^2$hrs and can not be used for long times of 10$^3$-10$^{6}$ hrs, but by ISM it can be used for long times creep prediction of more than 10$^4$hrs with most reliability.

  • PDF

A Study on Modelling for Prediction of Concrete Drying Shrinkage according to Aggregate Ratio of Concrete (잔골재율 변화에 따른 콘크리트 건조수축 모델링에 관한 연구)

  • Park, Do-kyong;Yoon, Yer-Wan;Kim, Kwang-Seo
    • Journal of the Korea Institute of Building Construction
    • /
    • v.4 no.4
    • /
    • pp.71-77
    • /
    • 2004
  • Drying Shrinkage has much complexity as it has relations with both internal elements of concrete and external factors. Therefore, experiments on Concrete Drying Shrinkage are carried out in this study under simplified circumstances applying temperature & Humidity test chamber which enables constant temperature and humidity. Comparative analyses have been made respectively according to the consequences aiming at modelling for prediction of Concrete Drying Shrinkage and making out measures to reduce it. Strain Rate of Drying Shrinkage of concrete under the condition of dry air appears to rise by about 20%-30% in proportion as the temperature rises $5^{\circ}C$ when the humidity was held below 10% compared under the condition of dry temperature & Humidity test chamber. Strain Rate of Drying Shrinkage in pit sand concrete increased 20% higher than measured when in river sand under the condition of 90-day material age. A general formula with two variables is derived as follow ${\varepsilon}={\alpha}_1+{\beta}_1x_1+{\beta}_2x_2+{\beta}_3x_1^2+{\beta}_5x_2^2$. and also graphed in 3 dimensions, enabling to apply to actual design and predict Strain Rate of Drying Shrinkage in concrete. The results of prediction of Rate of Drying Shrinkage by Response Surface Analysis are as follows. The coefficient of correlation of Drying Shrinkage in Concrete was over 90%.

Validation of the Strain Pattern Analysis (SPA) Measuring Technique (헬리콥터 Blade의 모드해석에 적용된 응력패턴해석 계측기법의 타당성)

  • Pakshir, Nabi
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 1996.04a
    • /
    • pp.361-369
    • /
    • 1996
  • The accurate prediction of modal parameters of a rotating blade is an important requirement in the assessment of the dynamics of a helicopter rotor. Indeed, predictions of flight loads and stability are normally dependent on initially predicting the undamped mode shapes. A measuring technique, known as Strain Pattern Analysis (SPA), appears to be the most successful technique for measuring the mode shapes of rotating blades. This method was developed to be used on actual aircraft so no attempt was made to measure rotating mode shapes directly in order to validate the SPA method. This report summarizes results from experimental investigations which were carried out to validate the SPA method for the prediction of aerodynamically damped modes of a rotating blade. A series of modal tests were carried out on two rotor models in which the non-rotating, undamped and aerodynamically damped rotating modes were measured directly (strain and displacement patterns). It is shown that the SPA method to be very successful in itself but there are a number of limitations in validating this technique. To provide data which could be used to confidently validate theoretical prediction codes, existing limitations should be addressed.

  • PDF

A Study on Modelling for Prediction of Concrete Drying Shrinkage according to Properties of Aggregate (잔골재 특성에 따른 콘크리트 건조수축 모델링에 관한 연구)

  • Park Do-Kyong;Yang Keek-Young
    • Journal of the Korea Institute of Building Construction
    • /
    • v.6 no.1 s.19
    • /
    • pp.73-77
    • /
    • 2006
  • Drying Shrinkage has much complexity as it has relations with both internal elements of concrete and external factors. Therefore, experiments on Concrete Drying Shrinkage are carried out in this study under simplified circumstances applying temperature & Humidity test chamber which enables constant temperature and humidify. Comparative analyses have been made respectively according to the consequences aiming at modelling for prediction of Concrete Drying Shrinkage and making out measures to reduce it. As a result Strain Rate of Drying Shrinkage of concrete was measured to increase by average $10{\times}10^{-5}$ in proportion to additional 4% increase in fine aggregate ratio, when water/cement ratio constant. Strain Rate of Drying Shrinkage in pit sand concrete increased 20% higher than measured when in river sand under the condition of 90-day material age. 6. Strain Rate of Drying Shrinkage in sea sand concrete increased $10%{\sim}15%$ higher than measured when in river sand. The results of prediction of Rate of Drying Shrinkage by Response Surface Analysis are as fellows. The coefficient of correlation of Drying Shrinkage in concrete was over 90%.

A simple prediction procedure of strain-softening surrounding rock for a circular opening

  • Wang, Feng;Zou, Jin-Feng
    • Geomechanics and Engineering
    • /
    • v.16 no.6
    • /
    • pp.619-626
    • /
    • 2018
  • A simple prediction procedure was investigated for calculating the stresses and displacements of a circular opening. Unlike existed approaches, the proposed approach starts each step with a radius increment. The stress for each annulus could be obtained analytically, while strain increments for each step can be determinate numerically from the compatility equation by finite difference approximation, flow rule and Hooke's law. In the successive manner, the distributions of stresses and displacements could be found. It should be noted that the finial radial stress and displacement were equal to the internal supporting pressure and deformation at the tunnel wall, respectively. By assuming different plastic radii, GRC and the evolution curve of plastic radii and internal supporting pressures could be obtained conveniently. Then the real plastic radius can be calculated by using linear interpolation in the evolution curve. Some numerical and engineering examples were performed to demonstrate the accuracy and validity for the proposed procedure. The comparisons results show that the proposed procedure was faster than that in Lee and Pietrucszczak (2008). The influence of annulus number and dilation on the accuracy of solutions was also investigated. Results show that the larger the annulus number was, the more accurate the solutions were. Solutions in Park et al. (2008) were significantly influenced by dilation.

Prediction of Long-Term Deflections of Reinforced Concrete Beams (철근콘크리트 보의 장기처짐 예측)

  • 김진근;이상순;양주경
    • Proceedings of the Korea Concrete Institute Conference
    • /
    • 1998.10a
    • /
    • pp.462-467
    • /
    • 1998
  • A rational method for prediction of long-term deflections of reinforced concrete beams under sustained loads was proposed. Strain and stress distributions of uncracked and fully cracked sections after creep and shrinkage were determined from the requirements of strain compatibility and force equilibrium of a section, and then long-term deflections were calculated from the section analysis results. In fully cracked section analysis, noncoincidence of the neutral axis of strain and the neutral axis of stress after creep and shrinkage was taken into account. The accuracy of the proposed method was verified by comparison with several experimental measurements of beam deflections. The proposed approximate procedure gave the better predictions than the existing approximate methods. At the same time, the proposed method also retained simplicity of the calculation, since maximum long-term deflection could be obtained without tedious integration of the curvatures.

  • PDF

A study of model to improve the accuracy of Springback prediction on sheet metal forming (판재 성형품의 탄성회복예측 정밀도 향상을 위한 모델 연구)

  • Kim M. C.;Lee Y. S.;Kwon Y. N.;Lee J. H.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
    • /
    • 2004.05a
    • /
    • pp.47-52
    • /
    • 2004
  • Springback comes from the release of residual stress after forming. The control of phenomenon is especially important in the sheet metal forming since there are no other practical methods available to correct the dimensional inaccuracy from springback. Therefore the accurate predication before the die machining has been a long goal in the Held of sheet metal forming. The aim of the present study is to enhance the prediction capability of finite element(FE) analysis for the springback phenomenon. For this purpose FE analysis for V-bending has been carried out with the commercial programs, LS-DYNA. The FE analysis results have been validated through the comparison of experimental. The experimental results measured directly by the strain gauge have given the confidence to FEA.

  • PDF

A Study On the Analysis Of Impact Strain for Hydraulic Breaker Chisel (유압식 착암기 치즐의 타격 변형량 해석에 관한 연구)

  • Park, J.W.;Lee, K.W.;Kim, H.E.
    • Transactions of The Korea Fluid Power Systems Society
    • /
    • v.4 no.4
    • /
    • pp.21-27
    • /
    • 2007
  • A hydraulic breaker for construction machinery generally used for the destroying and disassembling of buildings, crashing road pavement, breaking rocks at quarry and so on. So the measurement of the impact energy of a hydraulic breaker is very important thing to prove its capability to manufacturers and customers. Therefore the prediction of impact energy in design process is very helpful to the most of breaker manufacturers. In this study, we carried on modeling and simulation of a hydraulic breaker to predict impact energy via commercial CAE software. The modeling and simulation of a hydraulic breaker was achieved with two parts. One is a hydraulic circuit analysis part via AMESim and the other is impact strain analysis part via ANSYS.

  • PDF

Effect of Mean Stress on the Fatigue Life of Engine Mount and Life Prediction (방진고무부품 피로수명에 끼치는 평균하중의 영향 및 피로수명 예측)

  • Lee, H.J.;Kim, W.D.;Choi, B.I.;Woo, C.S.;Kim, J.Y.;Koh, S.K.
    • Proceedings of the KSME Conference
    • /
    • 2001.11a
    • /
    • pp.99-104
    • /
    • 2001
  • Effect of mean stress on the fatigue life of natural rubber for engine mount was investigated. Fatigue damage parameter based on the maximum Green-Lagrange strain was employed to account for the effect of mean stress. A procedure to predict the fatigue life of rubber components based on the maximum Green-Lagrange strain method was proposed. Nonlinear finite element analysis and fatigue test of jang-gu shape specimen were conducted to predict the fatigue life of engine mount. Predicted fatigue lives have a good agreement with tested lives within a factor of 3.

  • PDF

Prediction of Flow Stress of Steel in Consideration of Recrystallization (재결정거동을 고려한 강의 유동응력 예측)

  • 이동근;박종진
    • Proceedings of the Korean Society for Technology of Plasticity Conference
    • /
    • 1999.08a
    • /
    • pp.341-348
    • /
    • 1999
  • In the finite elemenet analysis of metal forming problems, the most critical input is the flow stress of workpiece. Conventionally, the flow stress of a metal at elevated temperatures is assumed to be a function of strain, strain rate and temperature, and obtained by experiment. However, if the workpiece is not continuously deformed as in mulit-pass rolling, the flow stress obtained by experiment is no longer valid because it does not consider the microstructure evolution occurring between deformations. In the present study, it was attemped that the flow stress of steel in the austenite region be obtained equations. It was applied to the prediction of flow stress variation at each stand during hot finishing rolling of steel.

  • PDF