DOI QR코드

DOI QR Code

Analysis of Three-Dimensional Cracks in Inhomogeneous Materials Using Fuzzy Theory

  • Lee, Yang-Chang (Division of Mechanical System Design Engineering, Kyonggi University) ;
  • Lee, Joon-Seong (Division of Mechanical System Design Engineering, Kyonggi University)
  • 발행 : 2005.06.01

초록

This paper describes a fuzzy-based system for analyzing the stress intensity factors (SIFs) of three-dimensional (3D) cracks. 3D finite element method(FEM) was used to obtain the SIF for subsurface cracks and surface cracks existing in inhomogeneous materials. A geometry model, i.e. a solid containing one or several 3D cracks is defined. Several distributions of local node density are chosen, and then automatically superposed on one another over the geometry model by using the fuzzy theory. Nodes are generated by the bucketing method, and ten-noded quadratic tetrahedral solid elements are generated by the Delaunay triangulation techniques. The singular elements such that the mid-point nodes near crack front are shifted at the quarter-points, and these are automatically placed along the 3D crack front. The complete FE model is generated, and a stress analysis is performed. The SIFs are calculated using the displacement extrapolation method. The results were compared with those surface cracks in homogeneous materials. Also, this system is applied to analyze cladding effect of surface cracks in inhomogeneous materials.

키워드

참고문헌

  1. I.S. Raju and J.C. Newman, 'Stress-Intensity Factors for a Wide Range of Semi-Elliptical Surface Cracks in Finite-Thickness Plates,' Engineering Fracture Mechanics, 11, pp. 817-829, 1979 https://doi.org/10.1016/0013-7944(79)90139-5
  2. D.M. Tracy, 'Finite Elements for Three Dimensional Elastic Crack Analysis,' Nuclear Engineering & Design, 26, pp. 282-290, 1974 https://doi.org/10.1016/0029-5493(74)90063-6
  3. W.S. blackbum, T.K. Hellen, 'Calculation of Stress Intensity Factors in Three-Dimensions by Finite Element Methods,' Int. J. for Numerical Methods in Engineering, 11, pp. 211-229, 1977 https://doi.org/10.1002/nme.1620110202
  4. R.C. Shah and A.S. Kobayashi, 'Stress Intensity Factors for an Elliptical Crack Approaching the Surface of a Semi-Infinite Solid,' Int. J. of Fracture, 9, pp. 133-146, 1973 https://doi.org/10.1007/BF00041855
  5. F.W. Smith, D.R. Sorensen, 'The Semi-Elliptical Surface Crack - A Solution by the Alternating Method,' Int. J. of Fracture, 12, pp. 45-57, 1973
  6. T. Nishioka and S.N. Atluri, 'Analytical Solution for Embedded Elliptical Cracks, and Finite Element Alternating Method for Elliptical Surface Cracks, Subjected to Arbitrary Loading,' Engineering Fracture Mechanics, 17, pp. 247-268, 1983 https://doi.org/10.1016/0013-7944(83)90032-2
  7. D.M. Parks, 'A Stiffness Derivative Finite Element Technique for Determination of Crack Tip Stress Intensity Factors,' Int. J. of Fracture, pp. 487-502, 1974
  8. G. Yagawa and T. Nishioka, 'Finite Element Analysis of Stress Intensity Factors for Plane Extension and Plate Bending Problems,' Int. J. of Numerical Method in Engineering, 14, pp. 727-740, 1979 https://doi.org/10.1002/nme.1620140507
  9. R.S. Barsoum, 'Further Application of Quadratic Isoparametric Finite Elements to Linear Fracture Mechanics of Plate Bending and General Shells,' Int. J. of Fracture, 11, pp. 167-169, 1975 https://doi.org/10.1007/BF00034724
  10. Joon-Seong Lee, 'Automated CAE System for Three-Dimensional Complex Geometry,' Doctoral Dissertation, Faculty of Engineering, The University of Tokyo, 1995
  11. Joon-Seong Lee et al., 'Automatic Mesh Generation for Three-Dimensional Structures Consisting of Free-Form Surfaces,' Transactions of the Society of CAD/CAM Engineers, Vol. 1, No. 1, pp. 65-75, 1996
  12. J.C. Newman, I.S. Raju, 'An Empirical Stress- Intensity Factor Equation for the Surface Crack,' Engineering Fracture Mechanics, 15, pp. 185- 192, 1981 https://doi.org/10.1016/0013-7944(81)90116-8