Investigation of incremental fatigue crack growth mechanisms using in situ SEM testing

Abstract A novel in situ scanning electron microscope (SEM) fatigue testing is proposed in this paper to investigate the fatigue crack growth mechanisms within one cyclic loading under plane stress conditions. The objectives of the experimental study are to verify the hypotheses of a small time scale fatigue crack growth model and to develop a new experimental methodology for the detailed mechanism investigation of fatigue crack growth. During the testing, one loading cycle is uniformly divided into a certain number of steps. At each step, high resolution images are taken around the crack tip region. Imaging analysis is used to quantify the crack growth kinetics and crack tip deformation behavior at any time instant in a loading cycle. Crack closure phenomenon is directly observed during the crack growth process in the current investigation. It is also observed that crack growth is not uniformly distributed within a loading cycle and only happens during a small portion of the loading path. Multiple mechanisms exist within one cyclic loading, which is not able to be captured using the classical cycle-based approaches. A detailed discussion is given based on the current investigation to explain some well-known issues in the classical fatigue theory.

[1]  V. Sánchez Gálvez,et al.  Modelling plasticity-induced fatigue crack closure , 1990 .

[2]  R. Pippan,et al.  CRACK CLOSURE: A CONCEPT OF FATIGUE CRACK GROWTH UNDER EXAMINATION , 1997 .

[3]  Paul Bowen,et al.  New perspective on slip band decohesion as unifying fracture event during fatigue crack growth in both small and long cracks , 1999 .

[4]  P. Bowen,et al.  On the finite element simulation of three-dimensional semi-circular fatigue crack growth and closure , 1998 .

[5]  Henrik Andersson,et al.  In-situ SEM study of fatigue crack growth behaviour in IN718 , 2004 .

[6]  Jong-Do Kim,et al.  Behavior of plasticity-induced crack closure and roughness-induced crack closure in aluminum alloy , 2001 .

[7]  K. Sadananda,et al.  Application of unified fatigue damage approach to compression–tension region , 1999 .

[8]  Daniel Kujawski,et al.  A new (ΔK+Kmax)0.5 driving force parameter for crack growth in aluminum alloys , 2001 .

[9]  Wanlin Guo,et al.  A model for the through-thickness fatigue crack closure , 1999 .

[10]  H. Maier,et al.  In-situ fatigue in an environmental scanning electron microscope - : Potential and current limitations , 2007 .

[11]  K. Sadananda,et al.  Multiple mechanisms controlling fatigue crack growth , 2003 .

[12]  J. Newman.  A crack opening stress equation for fatigue crack growth , 1984 .

[13]  E. Wolf.  Fatigue crack closure under cyclic tension , 1970 .

[14]  Wanlin Guo,et al.  Effects of strain hardening and stress state on fatigue crack closure , 1999 .

[16]  Zizi Lu,et al.  Small time scale fatigue crack growth analysis , 2010 .

[17]  S. Suresh.  Fatigue of materials , 1991 .

[18]  Daniel Kujawski,et al.  A fatigue crack driving force parameter with load ratio effects , 2001 .

[19]  M. Skorupa,et al.  Load interaction effects during fatigue crack growth under variable amplitude loading—a literature review. Part II: qualitative interpretation , 1999 .

[20]  A. K. Vasudevan,et al.  Reconsideration of fatigue crack closure , 1992 .

[21]  Jia Zhen Zhang,et al.  Direct high resolution in situ SEM observations of very small fatigue crack growth in the ultra-fine grain aluminium alloy IN 9052 , 2004 .

[22]  G. Glinka,et al.  A two parameter driving force for fatigue crack growth analysis , 2005 .

[23]  J. Newman.  A crack-closure model for predicting fatigue crack growth under aircraft spectrum loading , 1981 .

[24]  John W. Hutchinson,et al.  Analysis of Closure in Fatigue Crack Growth , 1978 .

[25]  Pommier,et al.  Bauschinger effect of alloys and plasticity-induced crack closure: a finite element analysis , 2000 .

[26]  P. Bowen,et al.  IN SITU SEM MEASUREMENTS OF CRACK CLOSURE FOR SMALL FATIGUE CRACKS IN ALUMINIUM 2024‐T351 , 1995 .

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