Fracture strength for a high strength steel bridge cable wire with a surface crack

Abstract In this paper, the fracture strength of a cracked suspension bridge wire is determined based on linear elastic fracture mechanics (LEFM). The wire is 5 mm in diameter, with an original ultimate strength of 1725 MPa and ultimate elongation that ranges between 5.5% and 6%. The average value of 65.7 MPa m for the wire fracture toughness, KC, was recently evaluated by the author. The state of practice is to use the ultimate strength of the cracked wire as obtained from tensile tests. This approach may overestimate the strength of the wire due to possible delamination and crack tip plasticity. A case study for a group of in situ wire breaks retrieved from a suspension bridge cable is presented. The failure analysis is performed based on both the fracture toughness criterion and the net section theory. The fracture toughness criterion produced more realistic results for the fracture strength of the wire. The decline in the fracture toughness and the corresponding reduction in the fracture strength of cracked degraded wire are predicted making use of the strain energy density criterion.

[1]  B. J. Alperin,et al.  Stress intensity factors for fatigue cracking in high-strength bolts , 1985 .

[2]  D. J. Cartwright,et al.  Strain energy release rates for a straight-fronted edge crack in a circular bar subject to bending , 1984 .

[3]  Andrea Carpinteri,et al.  Handbook of fatigue crack propagation in metallic structures , 1994 .

[4]  A. J. Bush,et al.  Experimentally determined stress-intensity factors for single-edge-crack round bars loaded in bending , 1978 .

[5]  A. Din,et al.  Stress intensity factors for fatigue cracking of round bars , 1981 .

[6]  H. Saunders,et al.  Advanced Fracture Mechanics , 1985 .

[7]  J. Byrne,et al.  Fatigue Initiation Study of TMT Eutectoid Steel , 1982 .

[8]  K. Gjerding-Smith,et al.  Wire fractures in locked coil cables , 2006 .

[9]  O. N. Romaniv,et al.  Method of evaluating the fracture toughness of a round bar and a high-strength wire , 1982 .

[10]  Ka Peters,et al.  Stress Intensity Factors for Single-Edge-Crack Solid and Hollow Round Bars Loaded in Tension , 1981 .

[11]  David Y. Jeong,et al.  Strain energy density approach to stable crack extension under net section yielding of aircraft fuselage , 1995 .

[12]  E. Madenci,et al.  Fracture initiation under gross yielding: Strain energy density criterion , 1983 .

[13]  G. Sih.  Strain-energy-density factor applied to mixed mode crack problems , 1974 .

[14]  G. Gray,et al.  Influence of microstructure on fatigue crack initiation in fully pearlitic steels , 1985 .

[15]  J. Llorca,et al.  FATIGUE LIMIT AND FATIGUE LIFE PREDICTION IN HIGH STRENGTH COLD DRAWN EUTECTOID STEEL WIRES , 1989 .

[16]  R. Forman,et al.  Growth behavior of surface cracks in the circumferential plane of solid and hollow cylinders , 1986 .

[17]  W. S. Blackburn.  Calculation of stress intensity factors for straight cracks in grooved and ungrooved shafts , 1976 .

[18]  Carl B. Østervig,et al.  Fatigue crack propagation in shafts with shoulder fillets , 1986 .

[19]  James C. Newman,et al.  Stress-intensity Factors for Circumferential Surface Cracks in Pipes and Rods under Tension and Bending Loads , 1986 .

[20]  T. J. Chung,et al.  Fracture and surface flaws in smooth and threaded round bars , 1986 .

[21]  J. Toribio,et al.  Stress corrosion behaviour of high-strength steel: design on the basis of the crack growth kinetics curve , 1995 .

[22]  D. J. Cartwright,et al.  Strain energy release rate for a circular-arc edge crack in a bar under tension or bending , 1985 .

[23]  D. J. Cartwright,et al.  Strain-energy release rate for a single-edge-cracked circular bar in tension , 1978 .