Statistical modeling of fatigue crack growth rate in pre-strained 7475-T7351 aluminum alloy

In this study, 7475-T7351 aluminum strips were subjected to two tensile pre-strain levels of 3% and 5%. Using compact tension C(T) specimens, fatigue crack growth tests were conducted under constant amplitude loading at stress ratios of 0.1 and 0.5 in air and at room temperature. Three fatigue crack growth rate (FCGR) models, namely, Collipriest, Priddle, and NASGRO were examined. To handle the effect of stress ratio on FCGR, Walker equivalent stress intensity factor model was used. Consequently, generalized Collipriest (GC), generalized Priddle (GP), and generalized NASGRO (GN) models were developed and fitted to the FCGR data. It was shown that both GC and GP models fit the FCGR data in a similar fashion. However, the GP model provided a better fit than the GC model. The GN model was found to be the most appropriate model for the data. Therefore, this model may be suggested for use in critical applications, such as aeronautical structural design.

[1]  Beat Kleiner,et al.  Graphical Methods for Data Analysis , 1983 .

[2]  J. Griffiths,et al.  EFFECTS OF CRACK CLOSURE AND MEAN STRESS ON THE THRESHOLD STRESS INTENSITY FACTOR FOR FATIGUE OF AN ALUMINIUM CASTING ALLOY , 1990 .

[3]  V. Radhakrishnan,et al.  An investigation of the effect of pre-straining on fatigue crack growth , 1975 .

[4]  Leonardo Barbosa Godefroid,et al.  Statistical modeling of fatigue crack growth rate in Inconel alloy 600 , 2007 .

[5]  M. Klesnil,et al.  Fatigue of metallic materials , 1980 .

[6]  J. T. Staley,et al.  Application of modern aluminum alloys to aircraft , 1996 .

[7]  R. D. Brown,et al.  Mean stress effects on crack propagation rate and crack closure in 7050-T76 aluminum alloy , 1978 .

[8]  Peter K. Liaw,et al.  Near-threshold fatigue crack growth behavior in metals , 1983 .

[9]  R. Ritchie,et al.  On the development of crack closure and the threshold condition for short and long fatigue cracks in 7150 aluminum alloy , 1985 .

[10]  S. Putatunda.  Influence of material strength level on fatigue crack closure , 1988 .

[11]  B. Karlsson,et al.  Influence of prestrain and ageing on near-threshold fatigue crack growth in fine-grained dual-phase steels , 1989 .

[12]  W. W. Milligan,et al.  High frequency fatigue crack propagation behavior of a nickel-base turbine disk alloy , 1999 .

[13]  M. O. Speidel,et al.  Stress corrosion cracking of two aluminium alloys: A comparison between experimental observations and data based on modelling , 1998 .

[14]  Robert J. Dexter,et al.  Fatigue and Fracture , 1999 .

[15]  H. Rao,et al.  Microstructural effects and crack closure during near , 1987, Metallurgical and Materials Transactions A.

[16]  Ian J. Polmear,et al.  Light Alloys: Metallurgy of the Light Metals , 1982 .

[17]  Robert O. Ritchie,et al.  AN ANALYSIS OF CRACK TIP SHIELDING IN ALUMINUM ALLOY 2124: A COMPARISON OF LARGE, SMALL, THROUGH‐THICKNESS AND SURFACE FATIGUE CRACKS , 1987 .

[18]  Royce Forman,et al.  Behavior of surface and corner cracks subjected to tensile and bending loads in a Ti-6Al-4V alloy , 1992 .

[19]  J. Devore,et al.  Applied statistics for engineers and scientists , 1994 .

[20]  L. Zhao,et al.  Lightweight materials for aircraft applications , 1995 .

[21]  Robert P. Wei,et al.  Crack closure in 2219-T851 aluminum alloy , 1977 .

[22]  Douglas M. Bates,et al.  Nonlinear Regression Analysis and Its Applications , 1988 .

[23]  E. A. Starke,et al.  Progress in structural materials for aerospace systems , 2003 .

[24]  David R. Anderson,et al.  Model selection and multimodel inference : a practical information-theoretic approach , 2003 .

[25]  P. C. Paris,et al.  A Critical Analysis of Crack Propagation Laws , 1963 .

[26]  J. Schijve,et al.  The effect of pre-strain on fatigue crack growth and crack closure , 1975 .

[27]  Takashi Miyata,et al.  The Influence of Microstructural Morphology and Prestrain on Fatigue Crack Propagation of Dual-phase Steels in the Near-threshold Region , 1999 .

[28]  R. Ritchie,et al.  Fatigue crack propagation in dual-phase steels: Effects of ferritic-martensitic microstructures on crack path morphology , 1984 .

[29]  W Wallace,et al.  AGARD Corrosion Handbook. Volume 1. Aircraft Corrosion: Causes and Case Histories , 1985 .

[30]  A. Smolej,et al.  The influence of the thermomechanical processing and forming parameters on superplastic behaviour of the 7475 aluminium alloy , 2001 .

[31]  R. Hertzberg,et al.  On the cyclic behavior of cast and extruded aluminum alloys. Part A: Fatigue crack propagation , 1983 .

[32]  M. Chaturvedi,et al.  The effect of thermomechanical treatment on the fatigue behaviour of 2036 aluminium alloy , 1981 .

[33]  D. Marquardt.  An Algorithm for Least-Squares Estimation of Nonlinear Parameters , 1963 .

[34]  Horst Buhl,et al.  Advanced aerospace materials , 1992 .

[35]  Subra Suresh,et al.  Fatigue crack growth threshold concepts , 1984 .