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Plastic Displacement Estimates in Creep Crack Growth Testing

크리프 균열 성장 실험을 위한 소성 변위 결정법

  • Published : 2006.10.01

Abstract

The ASTM test standard recommends the use of the compact tension specimen for creep crack growth rates measurement. In the creep crack growth rate test, the displacement rate due to creep is obtained by subtracting the contribution of elastic and plastic components from the total load line displacement rate based on displacement partitioning method fur determining $C^*-integral$, which involves Ramberg-Osgood (R-O) fitting procedures. This paper investigates the effect of the R-O fitting procedures on plastic displacement rate estimates in creep crack growth testing, via detailed two-dimensional and three-dimensional finite element analyses of the standard compact tension specimen. Four different R-O fitting procedures are considered; (i) fitting the entire true stress-strain data up to the ultimate tensile strength, (ii) fitting the true stress-strain data from 0.1% strain to 0.8 of the true ultimate strain, (iii) fitting the true stress-strain data only up to 5% strain, and (iv) fitting the engineering stress-strain data. It is found that the last two procedures provide reasonably accurate plastic displacement rates and thus should be recommended in creep crack growth testing. Moreover, several advantages of fitting the engineering stress-strain data over fitting the true stress-strain data only up to 5% strain are discussed.

Keywords

Creep Crack Growth Testing;Displacement Partitioning;J-Integral;Plastic Displacement Rate

References

  1. ASTM International, 1992, 'Standard Test Method for Measurement of Creep Crack Growth Rates in Metals,' ASTM Test Standard E1457-92
  2. Saxena, A., 1998, 'Nonlinear Fracture Mechanics for Engineers', ERC Press
  3. Saxena, A, Han, J. and Banerji, K., 1988, 'Creep Crack Growth Behavior in Power Plant Boiler and Steam Pipe Steels,' ASME Journal of Pressure Vessel Technology, Vol. 110, pp. 137-146 https://doi.org/10.1115/1.3265578
  4. Yoon, K.B., Saxena, A. and McDowell, D.L., 1992, 'Influence of Crack-Tip Cyclic Plasticity on Creepatigue Crack Growth,' Fracture Mechanics: Twenty Second Symposium, Vol. 1, ASTM STP 1131, pp. 367-392
  5. Huh, N,S., Kim, YJ. and Kim, YJ., 2001, 'Application of Enhanced Reference Stress Method to Nuclear Piping LBB Analysis: Finite Element Validation,' Transactions of the KSME(A), Vol. 25, No. 4, pp. 741-747
  6. Kim, YJ., Huh, N.S. and Kim, YJ., 2001, 'Effect of Liiders Strain on Engineering Crack Opening Displacement Estimations: Finite Element Study,' Fatigue and Fracture of Engineering Materials and Structures, Vol. 24, pp. 617-624 https://doi.org/10.1046/j.1460-2695.2001.00432.x
  7. Rahman, S., Brust, F., Ghadiali, N. and Wilkowski, G, 1998, 'Crack-Opening-Area Analyses for Circumferential Through-Wall Cracks in Pipes-Part II: Model Validation,' International Journal of Pressue Vessels and Piping, Vol. 75, pp. 375-396 https://doi.org/10.1016/S0308-0161(97)00082-3
  8. Webster, GA. and Ainsworth, R.A., 1994, 'High Temperature Component Life Assessment,' Chapman & Hall, London
  9. Riedel, H., 1987, 'Fracture at High Temperature,' Springer-Verlag, Berlin
  10. Ainsworth, R.A., 1993, 'The Use of a Failure Assessment Diagram for Initiation and Propagation of Defects at High Temperatures,' Fatigue and Fracture of Engineering Materials and Structures, Vol. 16, pp. 1091-1108 https://doi.org/10.1111/j.1460-2695.1993.tb00080.x
  11. Ainsworth, R.A, Hooton, D.G and Green, D., 1999, 'Failure Assessment Diagrams for High Temperature Defect Assessment,' Engineering Fracture Mechanics, Vol. 62, pp. 95-109 https://doi.org/10.1016/S0013-7944(98)00087-3
  12. Fookes, AI. and Smith, D.J., 2003, 'The Influence of Plasticity in Creep Crack Growth in Steels,' International Journal of Pressure Vessels and Piping, Vol. 80, pp. 453-463 https://doi.org/10.1016/S0308-0161(03)00100-5
  13. Kumar, V., German, M.D. and Shih, C.F., 1981, 'An Engineering Approach for Elastic-Plastic Fracture Analysis,' EPRl NP-1931
  14. Tada, H., 1973, 'The Stress Analysis of Cracks Handbook,' Paris Productions Inc
  15. Norris, D.M. and Chexal, B., 1987, 'PICEP: Pipe Crack Evaluation Program,' EPRl NP 3596-SR
  16. Scott, P., Olson, R., Marschall, C., Rudland, D., Francini, R., Wolterman, R., Hopper, A. and Wilkowski, G, 1996, 'Pipe System Experiments with Circumferential Cracks in Straight-Pipe Locations,' NUREG/CR-6389, USNRC
  17. Kim, YJ., Huh, N.S., Kim, YJ., Choi, YH. and Yang, J.S., 2004, 'On Relevant Ramberg-Osgood Fit to Engineering Nonlinear Fracture Mechanics Analysis,' ASME Journal of Pressure Vessel Technology, Vol. 126, pp. 277-283 https://doi.org/10.1115/1.1760767
  18. 'ABAQUS User's manual,' ABAQUS, Inc., 2003
  19. Kim, YJ., 1998, 'Note on Y/T vs. n for SlNTAP Procedure: Continuous and Dis-continuous Hardening,' In: Document generated within Brite-Euram Project 1426-Structural Integrity Assessment Procedures for European Industry - SlNTAP
  20. Bannister, AC., Ruiz Ocejo, J. and Gutierrez-Solana F., 2000, 'Implications of the Yield Stress/Tensile Stress Ratio to the SlNTAP Failure Assessment Diagrams for Homogeneous Materials,' Engineering Fracture Mechanics, Vol. 67, pp. 547-562 https://doi.org/10.1016/S0013-7944(00)00073-4