대한기계학회논문집A (Transactions of the Korean Society of Mechanical Engineers A)

  • 제35권4호
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  • Pages.375-381
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  • 2011
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  • 1226-4873(pISSN)
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  • 2288-5226(eISSN)
대한기계학회 (The Korean Society of Mechanical Engineers)
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Mg-Al-Zn 합금의 Paris-Erdogan 법칙에 따른 피로거동 파라미터의 확률론적 특성

Probabilistic Characteristics of Fatigue Behavior Parameter of Paris-Erdogan Law in Mg-Al-Zn Alloy

  • 최선순 (삼육대학교 카메카트로닉스학과)
  • 투고 : 2010.07.07
  • 심사 : 2011.02.14
  • 발행 : 2011.04.01
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초록

본 연구의 주목적은 마그네슘합금의 피로균열성장거동을 지배하는 파라미터들의 확률론적 특성을 규명하는 것이다. 피로균열전파실험은 AZ31 마그네슘합금의 CT 시편을 이용하여 통계적으로 수행하였으며, 시편두께, 하중비, 최대하중 등의 여러 가지 실험조건으로 실온에서 진행하였다. 이 실험을 통하여 획득한 통계적 피로 데이터를 이용하여 피로거동 파라미터의 확률적 변동성 해석과 함께 확률분포 적합성을 고찰하였다. 균열성장속도계수는 확률적으로 매우 큰 변동성을 나타내는 파라미터로 밝혀졌으며, 반면에 균열성장속도지수는 매우 작은 변동성을 나타냄으로써 재료상수로 볼 수 있을 것이다. 피로거동 파라미터인 균열성장속도계수와 균열성장속도지수에 가장 적합한 확률분포는 3-파라미터 Weibull 분포이며, 2-파라미터 Weibull 분포는 균열성장속도계수의 경우에만 양호한 적합성을 나타낸다는 것을 규명하였다.

The primary aim of this study is to investigate the probabilistic characteristics of the fatigue parameters that describe the fatigue crack growth behavior in magnesium alloy. Statistical fatigue crack propagation experiments have been performed on rolled AZ31 magnesium alloy CT specimens with different specimen thickness, load ratio, and maximum load at ambient temperature in a laboratory. Using the statistical fatigue data obtained from these experiments, the goodness-of-fit of the probability distribution of the fatigue behavior parameters is evaluated in this study by performing statistical analyses. The crack growth rate coefficient is a fatigue parameter having a very large COV(Coefficient of Variation), but the variation of a crack growth rate exponent is not substantial. It is considered that a crack growth rate exponent can be a material constant. It is also found that the best fit probability distribution of the parameters such as the crack growth rate coefficient and crack growth rate exponent for a magnesium alloy is a three-parameter Weibull distribution, and two-parameter Weibull distribution is a good distribution only for the crack growth rate coefficient.

키워드

참고문헌

  1. Mordike, B. L. and Ebert, T., 2001, “MagnesiumProperties-Applications-Potential,” Materials Scienceand Engineering, Vol. A302, pp. 37-45.
  2. Sivapragash, M., Lakshminarayanan, P.R. andKarthikeyan, R., 2008, “Fatigue Life Prediction ofZE41A Magnesium Alloy Using Weibull Distribution,”Materials and Design, Vol.29, pp. 1549-1553. https://doi.org/10.1016/j.matdes.2008.01.001
  3. Shih, T.-S., Liu, W.-S. and Chen, Y.-J., 2002,“Fatigue of As-extruded AZ61A Magnesium Alloy,”Materials Science & Engineering(A), Vol. 325, pp.152-162. https://doi.org/10.1016/S0921-5093(01)01411-3
  4. Choi, S. S., 2009, “Estimation of ProbabilityDistribution Fit for Fatigue Crack Propagation Life ofAZ31 Magnesium Alloy,” Transactions of theKSME(A), Vol. 33, No. 8, pp. 707-719. https://doi.org/10.3795/KSME-A.2009.33.8.707
  5. Choi, S. S., 2009, “Effect of Specimen Thickness onProbability Distribution of Fatigue Crack PropagationBehavior in Magnesium Alloy AZ31,” Journal of theKSMTE, Vol. 18, No. 4, pp. 395-400.
  6. Choi, S. S. and Lee, O. S., 2009, “Effect of MeanStress on Probability Distribution of Random GrownCrack Size in Magnesium Alloy AZ31,” Journal of theKSMTE, Vol. 18, No. 5, pp. 536-543.
  7. ASTM E647-00, 2000, Standard Test Method ofFatigue Crack Growth Rates, ASTM International,Pennsylvania.
  8. Dodson, B., 2006, The Weibull Analysis Handbook, ASQ Quality Press, Wisconsin, pp. 115-117.
  9. Choi, S. S., 2010, “Probabilistic Characteristics ofFatigue Behavior Parameter of Paris-Erdogan Law inMg-Al-Zn Alloy,” Proceedings of the KSME (ReliabilityDivision) Spring Conference 2010, pp. 92-99.

피인용 문헌

  1. Estimation of Empirical Fatigue Crack Propagation Model of AZ31 Magnesium Alloys under Different Specimen Thickness Conditions vol.15, pp.2, 2014, https://doi.org/10.5762/KAIS.2014.15.2.646