Effect of Stress State on Mode II Stable Crack Extension


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The effect of assumption of plane state of stress on the predictability of experimental results observed during the mode II stable crack growth (SCG) through 8 mm thick compact tension specimens (CTS) of a workhardening aluminum alloy (D16AT) has been studied. Experimental results include load-sliding displacement diagram, extent of SCG, crack front geometry and fracture surface fractographs. The experimental results show that the crack extends in its own plane, the fracture surface is flat, smooth and free of any shear lip. The crack front geometry, which is straight initially, remains mostly so throughout the SCG. Theoretical investigations have been done using an elastic-plastic finite element scheme and the COA/COD criterion as the criterion governing the growth. Finite element results, assuming plane stress and plane strain conditions separately, on the load-sliding displacement diagrams, J-resistance curve, plastic zones and variation of equivalent stress and strain along the crack-line ahead of the crack tip are also presented. The resistance curve is a straight-line and the magnitudes of equivalent stress and strain increases as the crack extension proceeds. In general, the predictions based on the assumption of plane state of stress are closer to the experimental results.



Key Engineering Materials (Volumes 297-300)

Edited by:

Young-Jin Kim, Dong-Ho Bae and Yun-Jae Kim




A.-H. I. Mourad, "Effect of Stress State on Mode II Stable Crack Extension ", Key Engineering Materials, Vols. 297-300, pp. 1604-1610, 2005

Online since:

November 2005




[1] Sha Jiangbo, Sun Jun, Zuh Pin, Deng Zengjie and Zhou Huijui: Study of the relationship between J-integral and COD parameters under mixed mode I+II loading in aluminium alloy Ly 12, International Journal of Fracture Vol. 104 No. 4 (2000).

DOI: https://doi.org/10.1023/a:1007647230722

[2] Michael A. Sutton, Michael L. Boone, Ma Fashang and Jeffrey D. Helm: Combined modling-experimental study of the crack opening displacement fracture criterion for charactrization of stable cack growth under mixwd mode I/Ii loading in thin sheet materials, Enginering Fracture Mechanics Vol. 66 No. 2 (2000).

DOI: https://doi.org/10.1016/s0013-7944(00)00011-4

[3] Michael A. Sutton, Deng Xiaomin, Ma Fashang, James C. Newman Jr. and James Mark: Development and application of a crack tip opening displacement-based mixed mode fracture criterion, International Journal of Solids and structures Vol. 37 No. 26 (2000).

DOI: https://doi.org/10.1016/s0020-7683(99)00055-4

[4] J.C. Newman Jr.: An elastic-plastic finite element analysis of crack initiation, stable crack growth and instability, in Fract. Mech. Fifteenth Symposium, ASTM STP 833, American Society for Testing and Materials, Philadelphia (Pa), USA (1984).

DOI: https://doi.org/10.1520/stp32551s

[5] K.N. Shivakumar and J.C. Newman Jr.: Numerical fracture simulation of bend specimen using CTOD criterion, Engng. Fract. Mech. Vol. 32 (1989), pp.203-210.

DOI: https://doi.org/10.1016/0013-7944(89)90293-2

[6] H. Andersson: A finite element representation of stable crack growth, J. Mech. Phys. Solids Vol. 21 (1973), pp.337-356.

[7] S.K. Maiti and A.H.I. Mourad: Criterion for mixed mode stable crack growth, Part II: Compact tension geometry with and without stiffener, Engng. Fract. Mechs. Vol. 52 (1995), pp.349-378.

DOI: https://doi.org/10.1016/0013-7944(95)00027-s

[8] A.H.I. Mourad and S.K. Maiti: Mode I and mixed - mode stable crack extensions through stiffened three - point bend specimens, Fatigue Fract. Engng. Mater. Struct. Vol. 18 (1995).

DOI: https://doi.org/10.1111/j.1460-2695.1995.tb00888.x

[9] A.H.I. Mourad and S.K. Maiti: Mode II stable crack growth, Fatigue Fracture of Engineering Materials and Structures 19, 75-84 (1996).

DOI: https://doi.org/10.1111/j.1460-2695.1996.tb00933.x

[10] H.A. Richard: A new compact shear specimen, Int. J. Fract. Vol. 17 (1981), pp. R105-R107.