Main Article Content
Abstract
In the thick components such as gas turbine disks, the cracks usually manifest in the form of part-through or embedded elliptical cracks. The shape of surface crack varies during the crack propagation and significantly affects the fatigue life predictions of the surface cracked components. In present work, crack propagation of semi-elliptical cracks in a finite width specimen of a gas turbine material subjected to fatigue load has been studied experimentally and numerically. The numerical simulation was accomplished by first extending the applicability of available stress intensity factor empirical equation for semi-elliptical cracks to finite width solid. Using this empirical equation for stress intensity factor, the effect of change in the crack shape on the crack propagation life is simulated by numerical models. Also, in order to include the effect of crack closure in the numerical prediction of growth of surface cracks, a ratio of crack closure factor between depth and surface locations of a semi-elliptical crack was obtained by experiments. The experimental observations were used in correlating the numerical predictions for crack shape progression and crack propagation life.
Keywords
Article Details
References
- Scott, P. M. and Thorpe, T. W., "A Critical Review of Crack Tip Stress Intensity Factors for Semi-elliptical Cracks", Fat. Fract. Engg. Mater. Struct., Vol.4, pp.291-309,1981.
- Jolles, M. and Tortoriello, V., "Effects of Constraint Variation on the Fatigue Growth of Surface Flaws", Fracture Mechanics: Fifteenth Symposium, ASTM STP 833, pp.300- 311,1984.
- Newman Jr. J. C. and Raju, I. S., "Prediction of Fatigue Crack Growth Patterns and Lives in Three-dimensional Cracked Bodies", Advances in Fracture Research, Eds. Valluri S. K., Taplin, D. M. R., Rama Rao, P., Knott, J. F. and Dubey, R., Pragamon Press, Vol. 3, pp.1597-1608, 1984.
- Jolles, M. and Tortoriello, V., "Geometric Variation During Fatigue Growth of Surface Flaws", Fracture Mech: Fourteenth Symposium Vol.I: Theory and Analysis, ASTM STP 791, Eds. Lewis, J. C. and Shines G., pp.287-307, 1983.
- Fleck, N. A., Smith, I. F. C. and Smith R. A., "Closure Behavior of Surface Cracks", Fat. Fract. Engg. Mater. Struct., Vol.6, pp.225-239, 1983.
- Kim, J. and Song, J., "Crack Growth and Closure Behaviour of Surface Cracks Under Axial Loading", Fat. Fract. Engg. Mater. Struct., Vol.15, pp. 477-489, 1992.
- Muller, H. M., Muller, S., Munz, D. and Neumann, J., "Extension of Surface Cracks During Cyclic Loading", Fracture Mechanics: Seventeenth Volume, ASTM STP-905, Eds. Underwood, J., Chait, R., Smith, C. W., Wilhem, D. B., Andrews W. A. and Newman Jr. J. C., pp.625-643, 1986.
- Yau, J. F., "An Empirical Surface Crack Solution for Fatigue Propagation Analysis of Notched Components", Fracture Mechanics: Seventeenth Volume, ASTM STP-905, Eds. Underwood, J., Chait, R., Smith, C. W., Wilhem, D. B., Andrews W. A. and Newman Jr. J. C., pp.601-624, 1986.
- Hodulak, L., Kordisch, M., Kunzelmann. and Sommer, E., "Growth of Part-through Cracks", Fracture Mechanics, ASTM STP 677, Ed. Smith, C. W.,pp.399-410, 1979.
- Van Stone, R. H., Gilbert, M. S., Gooden, O. C. and Laflen, J. H., "Constraint-loss Model for the Growth of Surface Cracks", Fracture Mechanics Symposium, ASTM STP 969, Ed. Cruse T. A., pp.637-656, 1988.
- Hosseni, A. and Mahmoud, M. A., "Evaluation of Stress Intensity Factor and Fatigue Growth of Surface Cracks in Tension Plates", Engg. Fract. Mech., Vol. 22, pp.957-974, 1985.
- Shuter, D. M. and Geary W., "Fatigue Crack Growth from Two-dimensional Surface Defects", Fat. Fract.Engg. Mater. Struct., Vol.18, pp. 653-659, 1995.
- Wilson, C. D., "Fracture Mechanics Life Prediction Computer Code Verification and Validation", Fracture Mechanics; 26th Volume, ASTM STP 1256, Eds. Walter, G. R., Underwood, J. H. and Newman Jr, J. C., pp.779-798, 1995.
- Mahmoud, M. A., "Quantitative Prediction of Growth Patterns of Surface Fatigue Cracks in Tension Plates", Engg. Fract. Mech., Vol. 30, pp.735746, 1988.
- Newman Jr. J. C. and Raju, I. S., "An Empirical Stress Intensity Factor Equation for the Surface Flaw", Engg. Fract. Mech.,Vol.15, pp.185-192, 1981.
- Raizenne, M. D., "Fatigue Crack Growth Results for Ti-6Al-4V, IMI685, and Ti-17", AGARD Engine Disc Cooperative Test Program, AGARD R-766 (Addendum), 1993.
- Newman Jr. J. C. and Raju, I. S., "Prediction of Fatigue Crack Growth Patterns and Lives in Three-dimensional Cracked Bodies", Advances in Fracture Research, Eds. Valluri S. R., Taplin, D. M. R., Rama Rao, P., Knott, J. F. and Dubey, R., Pragamon Press, 3: pp.1597-1608, 1984.
- Patel, S. K., "Experimental and Numerical Studies on Fatigue Crack Growth of Single and Interacting Multiple Surface Cracks", Ph. D. Thesis, Indian Institute of Science, Bangalore, India, May, 2000.
- Inconel Alloy 718, Technical Bulletin, Inco Alloys International, Inc., 4th Edition, West Virginia, 1985.
- Seshadri, B.R., Dattaguru, B., Ramamurthy, T. S., Sundar, R. and Prakash, R. V., "Finite Element Simulation and Experimental Correlation of Crack Closure Phenomenon Under Cyclic Loading", J. Aero.Soc. of India, Vol.45, pp.281-292, 1993.
- KRAK gage and FRACTOMAT Bulletin, TTI Division, Hartrun Corporation, Chaska, MN, USA.
- Soboyejo, W.O. and Knott, J. F., An Investigation of Crack Closure and the Propagation of Semi-elliptical Fatigue Cracks in QIN (HY80) Pressure Vessel Steel, Int. J. Fat., Vol. 17, pp.577-581, 1995.
- Software and Executive Unit Reference, Ver.1.1, System-4000, Model 510, Stress Analysis Data System, Instruments Div.,Measurements Group Inc., Rayleigh, 1992.
References
Scott, P. M. and Thorpe, T. W., "A Critical Review of Crack Tip Stress Intensity Factors for Semi-elliptical Cracks", Fat. Fract. Engg. Mater. Struct., Vol.4, pp.291-309,1981.
Jolles, M. and Tortoriello, V., "Effects of Constraint Variation on the Fatigue Growth of Surface Flaws", Fracture Mechanics: Fifteenth Symposium, ASTM STP 833, pp.300- 311,1984.
Newman Jr. J. C. and Raju, I. S., "Prediction of Fatigue Crack Growth Patterns and Lives in Three-dimensional Cracked Bodies", Advances in Fracture Research, Eds. Valluri S. K., Taplin, D. M. R., Rama Rao, P., Knott, J. F. and Dubey, R., Pragamon Press, Vol. 3, pp.1597-1608, 1984.
Jolles, M. and Tortoriello, V., "Geometric Variation During Fatigue Growth of Surface Flaws", Fracture Mech: Fourteenth Symposium Vol.I: Theory and Analysis, ASTM STP 791, Eds. Lewis, J. C. and Shines G., pp.287-307, 1983.
Fleck, N. A., Smith, I. F. C. and Smith R. A., "Closure Behavior of Surface Cracks", Fat. Fract. Engg. Mater. Struct., Vol.6, pp.225-239, 1983.
Kim, J. and Song, J., "Crack Growth and Closure Behaviour of Surface Cracks Under Axial Loading", Fat. Fract. Engg. Mater. Struct., Vol.15, pp. 477-489, 1992.
Muller, H. M., Muller, S., Munz, D. and Neumann, J., "Extension of Surface Cracks During Cyclic Loading", Fracture Mechanics: Seventeenth Volume, ASTM STP-905, Eds. Underwood, J., Chait, R., Smith, C. W., Wilhem, D. B., Andrews W. A. and Newman Jr. J. C., pp.625-643, 1986.
Yau, J. F., "An Empirical Surface Crack Solution for Fatigue Propagation Analysis of Notched Components", Fracture Mechanics: Seventeenth Volume, ASTM STP-905, Eds. Underwood, J., Chait, R., Smith, C. W., Wilhem, D. B., Andrews W. A. and Newman Jr. J. C., pp.601-624, 1986.
Hodulak, L., Kordisch, M., Kunzelmann. and Sommer, E., "Growth of Part-through Cracks", Fracture Mechanics, ASTM STP 677, Ed. Smith, C. W.,pp.399-410, 1979.
Van Stone, R. H., Gilbert, M. S., Gooden, O. C. and Laflen, J. H., "Constraint-loss Model for the Growth of Surface Cracks", Fracture Mechanics Symposium, ASTM STP 969, Ed. Cruse T. A., pp.637-656, 1988.
Hosseni, A. and Mahmoud, M. A., "Evaluation of Stress Intensity Factor and Fatigue Growth of Surface Cracks in Tension Plates", Engg. Fract. Mech., Vol. 22, pp.957-974, 1985.
Shuter, D. M. and Geary W., "Fatigue Crack Growth from Two-dimensional Surface Defects", Fat. Fract.Engg. Mater. Struct., Vol.18, pp. 653-659, 1995.
Wilson, C. D., "Fracture Mechanics Life Prediction Computer Code Verification and Validation", Fracture Mechanics; 26th Volume, ASTM STP 1256, Eds. Walter, G. R., Underwood, J. H. and Newman Jr, J. C., pp.779-798, 1995.
Mahmoud, M. A., "Quantitative Prediction of Growth Patterns of Surface Fatigue Cracks in Tension Plates", Engg. Fract. Mech., Vol. 30, pp.735746, 1988.
Newman Jr. J. C. and Raju, I. S., "An Empirical Stress Intensity Factor Equation for the Surface Flaw", Engg. Fract. Mech.,Vol.15, pp.185-192, 1981.
Raizenne, M. D., "Fatigue Crack Growth Results for Ti-6Al-4V, IMI685, and Ti-17", AGARD Engine Disc Cooperative Test Program, AGARD R-766 (Addendum), 1993.
Newman Jr. J. C. and Raju, I. S., "Prediction of Fatigue Crack Growth Patterns and Lives in Three-dimensional Cracked Bodies", Advances in Fracture Research, Eds. Valluri S. R., Taplin, D. M. R., Rama Rao, P., Knott, J. F. and Dubey, R., Pragamon Press, 3: pp.1597-1608, 1984.
Patel, S. K., "Experimental and Numerical Studies on Fatigue Crack Growth of Single and Interacting Multiple Surface Cracks", Ph. D. Thesis, Indian Institute of Science, Bangalore, India, May, 2000.
Inconel Alloy 718, Technical Bulletin, Inco Alloys International, Inc., 4th Edition, West Virginia, 1985.
Seshadri, B.R., Dattaguru, B., Ramamurthy, T. S., Sundar, R. and Prakash, R. V., "Finite Element Simulation and Experimental Correlation of Crack Closure Phenomenon Under Cyclic Loading", J. Aero.Soc. of India, Vol.45, pp.281-292, 1993.
KRAK gage and FRACTOMAT Bulletin, TTI Division, Hartrun Corporation, Chaska, MN, USA.
Soboyejo, W.O. and Knott, J. F., An Investigation of Crack Closure and the Propagation of Semi-elliptical Fatigue Cracks in QIN (HY80) Pressure Vessel Steel, Int. J. Fat., Vol. 17, pp.577-581, 1995.
Software and Executive Unit Reference, Ver.1.1, System-4000, Model 510, Stress Analysis Data System, Instruments Div.,Measurements Group Inc., Rayleigh, 1992.