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

The Korean Society of Mechanical Engineers (대한기계학회)
권호 표지
DOI QR코드

DOI QR Code

Effect of Initial Crack Location on Spatial Randomness of Fatigue Crack Growth Resistance in Friction Stir Welded AA7075-T651 Plates

마찰교반용접된 AA7075-T651 판재의 피로균열전파저항의 공간적 불규칙성에 미치는 초기균열위치의 영향

  • Kim, Seon Jin (Dept. of Mechanical & Automotive Engineering, Pukyong Nat'l Univ.)
  • 김선진 (부경대학교 기계자동차공학과)
  • Received : 2014.06.05
  • Accepted : 2014.07.09
  • Published : 2014.09.01
Download PDF
⟨ Previous Next ⟩

Abstract

In the present paper, the effects of initial crack location on spatial randomness of fatigue crack growth resistance (FCGR) in friction stir welded (FSWed) AA7075-T651 plates were studied. The objective of this study is to characterize the statistical properties of FCGR for three different types of initial crack location (ICL) specimens. In this work, the FCGR coefficients were treated as a spatial random process. It was found that the FCGR coefficients for all initial crack location specimens closely followed a two parameter Weibull distribution. The shape parameter of the Weibull distribution for BM-ICL specimens showed the largest value of 7.50, and that for the WM-ICL specimens showed the smallest value of 2.61. In addition, the autocorrelation functions for all the ICL specimens followed the exponential function.

본 연구에서는 마찰교반용접된 AA7075-T651 판재의 피로균열전파저항의 공간적 불규칙성에 미치는 초기균열위치의 영향에 대하여 고찰되었다. 본 연구의 목적은 3가지 다른 초기균열위치에 따른 피로균열전파저항의 통계적 성질을 특성화하는 것이다. 본 연구에서는 피로균열전파저항 계수를 하나의 확률과정으로 취급하였다. 본 연구를 통하여 모든 초기균열위치의 시험편에 대한 피로균열전파저항 계수는 2-파라메터 Weibull 분포에 잘 따름을 알 수 있었다. 피로균열전파저항 계수의 확률분포의 형상 파라메터는 BM-ICL 시험편이 7.50으로 가장 크게 나타났으며, WM-ICL 시험편이 2.61로 가장 낮았다. 또한 피로균열전파저항 계수의 자기상관함수는 초기균열위치 시험편에 관계없이 모두 지수함수로 평가될 수 있음을 알았다.

Keywords

References

  1. Bussu, G. and Irving, P. E., 2003, "The Role of Residual Stress and Heat Affected Zone Properties on Fatigue Crack Propagation in Friction Stir Welded 2024-T351 Aluminum Joints," International Journal of Fatigue, Vol. 25, pp. 77-83. https://doi.org/10.1016/S0142-1123(02)00038-5
  2. Pouget, G. and Reynolds, A. P., 2008, "Residual Stress and Microstructure Effects on Fatigue Crack Growth in AA2050 Friction Stir Welds," International Journal of Fatigue, Vol. 30, pp. 463-472. https://doi.org/10.1016/j.ijfatigue.2007.04.016
  3. Kim, S. S., Lee, C. G. and Kim, S. J., 2008, "Fatigue Crack Propagation Behavior of Friction Stir Welded 7083-H31 and 6061-T651 Aluminum Alloys," Materials Science and Engineering A 478, pp. 56-64. https://doi.org/10.1016/j.msea.2007.06.008
  4. Fratini, L., Pasta, S. and Reynolds, A. P., 2009, "Fatigue Crack Growth in 2024-T351 Friction Stir Welded Joints: Longitudinal Residual Stress and Microstructural Effects," International Journal of Fatigue, Vol. 31, pp. 495-500. https://doi.org/10.1016/j.ijfatigue.2008.05.004
  5. Maduro, L. P., Baptista, C. A. R. P., Torres, M. A. S. and Souza, R. C., 2011, "Modeling the Growth of LT and TL-Oriented Fatigue Cracks in Longitudinally and Transversely Pre-Strained Al 2524-T3 Alloy," Engineering Procedia, Vol. 10, pp. 1214-1219. https://doi.org/10.1016/j.proeng.2011.04.202
  6. Lemmem, H. J. K., lderliesten, R. C., Benedictus, R., 2011, "Marco and Microscopic Observations of Fatigue Crack Growth in Friction Stir Welded Aluminum Joints," Engineering Fracture Mechanics, Vol. 78, pp. 930-943. https://doi.org/10.1016/j.engfracmech.2011.01.018
  7. Hatamleh, O., Lyones J. and Forman, R., 2007, "Laser and Shot Peening Effects on Fatigue Crack Growth in Friction Stir Welded 7075-T7351 Aluminum Alloy Joints, International Journal of Fatigue, Vol. 29, pp. 421-434. https://doi.org/10.1016/j.ijfatigue.2006.05.007
  8. Tra, T. H., Okazaki, M. and Suzuki, K., 2012, "Fatigue Crack Propagation Behavior in Friction Stir Welding of AA6063-T5: Roles of Residual Stress and Microstructure," International Journal of Fatigue, Vol. 43, pp. 23-29. https://doi.org/10.1016/j.ijfatigue.2012.02.003
  9. Dai, Q, Liang, Z., Chen, G., Meng, L. and Shi, Q., 2013, "Explore the Mechanism of High Fatigue Crack Propagation Rate in Fine Microstructure of Friction Stir Welded Aluminum Alloy," Materials Science and Engineering A 580, pp. 184-190. https://doi.org/10.1016/j.msea.2013.05.057
  10. Mishra, R. S. and Ma, Z. Y., 2005, "Friction Stir Welding and Processing," Materials Science and Engineering, R 50, pp. 1-78.
  11. Jeong, Y. H. and Kim, S. J., 2013, "Experimental Investigation of Fatigue Crack Growth Behavior in Friction Stir Welded 7075-T651 Aluminum Alloy Joints under Constant Stress Intensity Factor Range Control Testing," Trans. Korean Soc. Mech. Eng. A, Vol. 37, No. 6, pp. 775-782 https://doi.org/10.3795/KSME-A.2013.37.6.775
  12. Jeong, Y. H. and Kim, S. J., 2013, "Spatial Randomness of Fatigue Crack Growth Rate in Friction Stir Welded 7075-T651 Aluminum Alloy Welded Joints(case of LT Orientation Specimen)," Trans. Korean Soc. Mech. Eng. A, Vol. 37, No. 9, pp. 1109-1116. https://doi.org/10.3795/KSME-A.2013.37.9.1109
  13. Ahn, S. H. and Kim, S. J., 2013, "Statistical Distribution of Fatigue Crack Growth Rate for Friction Stir Welded Joints of Al7075-T651," Trans. of the KSPSE, Vol. 17, No. 4, pp. 86-93.
  14. Sobbxzyk, K., 1993, "Stochastic Approach of Fatigue," Springer-Verlag, Wien-New York, pp. 1-301.
  15. Ichkawa, M. and Nakamura, T., 1988, "Methods for Randomization of Parameters in the Fatigue Crack Propagation Law da/dN=C(${\Delta}K)^m$," Trans. of the Materials, Vol. 34, No. 378, pp. 321-326.
  16. Kong, Y. S. and Kim, S. J., 2014, "Marco and Microscopic Observations of Fatigue Crack Growth in Friction Stir Welded 7075-T651 Aluminum Alloy Plates," Trans. of the KSPSE, Submitted.
  17. Ortiz, K. and Kiremidjian, A. S., 1986, "Stochastic Modelling of Crack Growth," Engineering Fracture Mechanics, Vol. 29, pp. 317-334.
  18. Itagaki, H., Ishizuka, T. and Kim, S. J., 1991, "Effect of Spatial Distribution of Material Properties on the Experimental Estimation: Part 1 Fatigue Crack Growth," Journal of Society of Naval Architects Japan, Vol. 170, pp. 327-336.