Some contraindications of hole expansion in riveted joints

Abstract Comparable fatigue tests were carried out on aluminium alloy 7475-T7351 double butt joints with untreated and with cold expanded holes. Surprisingly, the behaviour of the specimens having cold expanded holes was worse than that of specimens with untreated holes. This result was attributed to the surface upset which was present in cold expanded holes. Several hypotheses were formulated and experimentally verified to overcome this problem, such as deeper hole deburring, rivet diameter, joint design and grip material, steel instead of aluminium alloy. Additional tests demonstrated that the problem was not present in sealed joint as the surface upset was hidden in the sealant thickness. Sealants have detrimental effects in the fatigue resistance of riveted joints, as they increase the load transferred by rivet bearing. The hole expansion is beneficial in this condition, while in un-sealed joints its effect must be accurately evaluated. Other authors too highlighted possible problems due to surface upset, up to suggest to eliminate it. Only in a very few cases, a reduction of fatigue life as a consequence of hole expansion was observed.

[1]  R. Kaye,et al.  Investigation of stress intensity factor for overloaded holes and cold expanded holes , 2011 .

[2]  Eggert D. Reese,et al.  The Variable Expansion Process — a New Cost Efficient Method for Cold Working Fastener Holes in Aluminium Aircraft Structures , 2009 .

[3]  S. Pasta.  Residual Stresses Induced by Cold Expansion of Adjacent and Cut-Out Holes , 2013 .

[4]  Mark Ofsthun.  When fatigue quality enhancers do not enhance fatigue quality , 2003 .

[5]  Noureddine Benseddiq,et al.  Effect of residual stresses induced by cold expansion on the crack growth in 6082 aluminum alloy , 2013 .

[6]  J. M. Finney.  Cold Expansion and Interference for Extending the Fatigue Life of Multi- Layer Metal Joints , 1993 .

[7]  Hao Wu.  On the prediction of initiation life for fatigue crack emanating from small cold expanded holes , 2012 .

[9]  Saravanan Karuppanan,et al.  Finite Element Simulation of Residual Stresses in Cold-expanded Plate , 2013 .

[10]  Wuzhu Yan,et al.  Effect of split sleeve cold expansion on cracking behaviors of titanium alloy TC4 holes , 2012 .

[11]  J. T. Maximov,et al.  A novel method and tool which enhance the fatigue life of structural components with fastener holes , 2013 .

[12]  D. Fanteria,et al.  Experimental and analytical assessment of fatigue and crack propagation in cold worked open hole specimens , 2013 .

[13]  T. N. Chakherlou,et al.  ON THE FATIGUE BEHAVIOR OF COLD EXPANDED FASTENER HOLES SUBJECTED TO BOLT TIGHTENING , 2011 .

[14]  H. Taghizadeh,et al.  Experimental and numerical comparison of cold expansion and interference fit methods in improving fatigue life of holed plate in double shear lap joints , 2013 .

[15]  L. Schwarmann.  On improving the fatigue performance of a double-shear lap joint , 1983 .

[16]  J. Y. Mann,et al.  Fatigue characteristics of joints with holes cold-expanded in a multi-layer stack , 1989 .

[17]  Joseph L. Phillips.  Fatigue Improvement by Sleeve Cold Working , 1973 .

[18]  B. Zuccarello,et al.  Numerical-experimental Method for the Analysis of Residual Stresses in Cold-expanded Holes , 2013 .

[19]  J. Mann,et al.  The Use of Interference-Fit Bolts or Bushes and Hole Cold Expansion for Increasing the Fatigue Life of Thick-Section Aluminium Alloy Bolted Joints , 1983 .

[20]  G. Marannano,et al.  Effect of cold working and ring indentation on fatigue life of aluminum alloy specimens , 2015, Experimental Techniques.