Effect of hardening induced by cold expansion on damage fatigue accumulation and life assessment of Aluminum alloy 6082 T6

Hole cold expansion (HCE) is an effective method to extend the fatigue life of mechanical structures. During cold expansion process compressive residual stresses around the expanded hole are generated. The enhancement of fatigue life and the crack initiation and growth behavior of a holed specimen were investigated by using the 6082 Aluminum alloy. The present study suggests a simple technical method for enhancement of fatigue life by a cold expansion hole of pre-cracked specimen. Fatigue damage accumulation of cold expanded hole in aluminum alloy which is widely used in transportation and in aeronautics was analyzed. Experimental tests were carried out using pre-cracked SENT specimens. Tests were performed in two and four block loading under constant amplitude. These tests were performed by using two and four blocks under uniaxial constant amplitude loading. The increasing and decreasing loading were carried. The experimental results were compared to the damage calculated by the Miner's rule and a new simple fatigue damage indicator. This comparison shows that the 'damaged stress model', which takes into account the loading history, yields a good estimation according to the experimental results. Moreover, the error is minimized in comparison to the Miner's model.

[1]  Cgc Poussard,et al.  Effect of residual stress around cold worked holes on fracture under superimposed mechanical load , 1999 .

[2]  G. Mesmacque,et al.  Effects of expanded and non-expanded hole on the delay of arresting crack propagation for aluminum alloys , 2000 .

[3]  M. J. Pavier,et al.  The effect of cold expansion on fatigue crack growth from open holes at room and high temperature , 2001 .

[5]  Yoshikazu Nakai,et al.  Fracture mechanics approach to fatigue crack initiation from deep notches , 1983 .

[6]  Abdelwaheb Amrouche,et al.  Sequential law in multiaxial fatigue, a new damage indicator , 2005 .

[7]  Stjepan Jecić,et al.  Validation of crack arrest technique by numerical modelling , 1997 .

[8]  A. Aid,et al.  Fatigue life prediction under variable loading based on a new damage model , 2011 .

[9]  Cgc Poussard,et al.  Analytical and finite element predictions of residual stresses in cold worked fastener holes , 1995 .

[10]  A. Aid,et al.  Numerical study of the optimum degree of cold expansion: Application for the pre-cracked specimen with the expanded hole at the crack tip , 2008 .

[11]  William N. Sharpe,et al.  An experimental study of fatigue crack initiation and growth from coldworked holes , 1979 .

[12]  Gopal S. Upadhyaya,et al.  Material Science and Engineering , 2007 .

[13]  Cgc Poussard,et al.  A finite element simulation of the cold working process for fastener holes , 1997 .

[14]  T. Bui-Quoc,et al.  EFFECT OF RE‐COLD WORKING ON FATIGUE LIFE ENHANCEMENT OF A FASTENER HOLE , 2007 .

[15]  M. J. Pavier,et al.  Prediction of the growth rate for fatigue cracks emanating from cold expanded holes , 2004 .

[16]  Simon Ho,et al.  Fatigue analysis of crankshaft sections under bending with consideration of residual stresses , 2005 .

[17]  S. Pasta.  Fatigue crack propagation from a cold-worked hole , 2007 .

[18]  E. W. C. Wilkins,et al.  Cumulative damage in fatigue , 1956 .