International Journal of Fracture

, Volume 131, Issue 4, pp 337–349 | Cite as

Validation of the state-space model of fatigue crack growth in ductile alloys under variable-amplitude load via comparison of the crack-opening stress data

  • Ravindra Patankar
  • Rong Qu


A state-space model of fatigue crack growth in ductile alloys under variable-amplitude load was presented by Patankar and Ray (Patankar et al. (1998). International Journal of Fracture, 90, 235--249; Patankar and Ray (2000). Engineering Fracture Mechanics, 66, 136--151). This paper presents improvements to the state-space model, through enhancements in the calculations of the constraint factor. These improvements are similar to the calculation procedure of the constraint factor in FASTRAN-II model, which has been extensively validated (Newman (1981). Methods and Models for Predicting Fatigue Crack Growth under Random Loading, ASTM STP 784, 53--84; Newman (1982). Design of Fatigue and Fracture Resistant Structures, ASTM STP 761, 255--277; Newman (1984). International Journal of Fracture, 24, R131--R135; Newman (1992). NASA Technical Memorandum}, 104159). The model predictions are compared to various crack growth data as well as FASTRAN-II predictions. Heather to, the state-space model has only been validated through the crack-length data but this paper presents the validation of the state-space model via comparison of the experimental crack-opening stress and crack-length data, thus involving both the states of the state-space model in experimental validation of the model. The experimental data are also compared to the crack-opening stress in FASTRAN-II predictions. Simulation results validate the modeling method of treating the crack-opening stress as a state variable or internal variable. The state-space model considerably reduces the computational complexity of the fatigue crack growth model under variable-amplitude load.


Crack-closure crack-opening stress state-space variable-amplitude load 


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  1. Patankar, R.P., Ray, A., Lakhtakia, A. 1998A state-space model of fatigue crack growthInternational Journal of Fracture90235249Google Scholar
  2. Patankar, R.P., Ray, A. 2000State-space modeling of fatigue crack growth in ductile alloysEngineering Fracture Mechanics66136151Google Scholar
  3. Newman, J.C.,Jr. 1981A crack-closure model for predicting fatigue crack growth under aircraft loadingMethods and Models for Predicting Fatigue Crack Growth under Random LoadingASTM STP 7485384Google Scholar
  4. Newman, J.C.,Jr. 1982Prediction of fatigue crack growth under variable-amplitude and spectrum loading using a closure modelDesign of Fatigue and Fracture Resistant StructuresASTM STP 761255277CrossRefGoogle Scholar
  5. Newman, J.C. Jr. (1984). A crack-opening stress equation for fatigue crack growth. International Journal of Fracture 24, R131–R135.Google Scholar
  6. Newman, J.C. Jr. (1992). FASTRAN-II – A Fatigue Crack Growth Structural Analysis Program. NASA Technical Memorandum 104159, Langley Research Center.Google Scholar
  7. Elber, W. (1970). Engineering Fracture Mechanics.Google Scholar
  8. Paris, P.C., Erdogan, F. 1960A critical analysis of crack propagation lawsJournal of Basic EngineeringASME Trans 85528534Google Scholar
  9. Harter, J.A. AFGROW Users’ guide and technical manual. Report No. AFRL-VA-WP-1999–3016, Air Force Research Laboratory.Google Scholar
  10. Schijve, J. and Jacobs, F.A. Tromp, P.J. (1971). The effect of load sequence under fatigue crack propagation under random loading and program loading. NLR TR 71014 U, National Aerospace Laboratory NLR, The Netherlands.Google Scholar
  11. Schijve, J. 1974Fatigue damage accumulation and incompatible crack front orientationEngineering Fracture Mechanics6245252Google Scholar
  12. Schijve, J. 1976Observations on the prediction of fatigue crack growth propagation under variable-amplitude loadingFatigue Crack Growth under Spectrum LoadsASTM STP 595323Google Scholar
  13. Yisheng, W., Schijve, J. 1995Fatigue crack-closure measurements on 2024-T3 sheet specimensFatigue and Fracture of Engineering Materials and Structures18917921Google Scholar
  14. Porter, T.R. 1972Method of analysis and prediction for variable amplitude fatigue crack growthEngineering Fracture Mechanics4717736Google Scholar
  15. McMillan, J.C. and Pelloux, R.M.N. (1967). Fatigue crack propagation under program and random loads. Fatigue Crack Propagation, ASTM STP 415, 505–532 (Also BSRL Document D1–82–0558 1966).Google Scholar
  16. McMaster, F.J. and Smith, D.J. (1999). Effect of load excursions and specimen thickness on crack-closure measurement. Advances in Fatigue Crack-closure Measurements and Analysis, ASTM STP 1343, West Conshohocken, 246--264.Google Scholar
  17. Kailath, T. (1980). Linear Systems, Prentice-Hall Englewood Cliffs.Google Scholar

Copyright information

© Springer 2005

Authors and Affiliations

  1. 1.Intelligent Automation, Inc.RockvilleUSA
  2. 2.Department of Mechanical EngineeringMichigan Technological UniversityHoughtonUSA

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