Evaluation of a leaf spring failure
The determination of the point of failure during an accident sequence of a rear leaf spring in a sport utility vehicle is presented in terms of fracture surface analysis and residual-strength estimates. Marks at the scene of the accident pointed to two possibilities for the point of failure: marks in the roadway at the start of the accident sequence and a rock strike near the end of the sequence. Evidence from rust and chemical contamination on the fracture pointed to the spring having been cracked in half prior to the accident. Extensive woody fracture and secondary cracking at the midplane of the spring was evidence for segregation and weakness in the spring. Stress estimates for the effect of both the weakness and prior cracking on the residual strength of the spring revealed reductions in strength of the spring that could produce fracture at the start of the accident sequence. The point of failure of the spring was placed at the start of the accident sequence.
Keywordsfracture mechanics leaf spring failure leaf spring stress analysis woody fracture
Unable to display preview. Download preview PDF.
- 1.J. Goldstein et al.: Scanning Electron Microscopy and X-Ray Analysis, 3rd ed., Kluwer Academic/Plenum, New York, NY, 2003, pp. 476–79.Google Scholar
- 2.A.J. Tetelman and A.J. McEvily: Fracture of Structural Materials, John Wiley, New York, NY, 1967, pp. 105–07.Google Scholar
- 3.R.W. Hertzberg: Deformation and Fracture Mechanics of Engineering Materials, 3rd ed., John Wiley, New York, NY, 1983, pp. 258–59.Google Scholar
- 4.H.E. McGannon, ed.: The Making, Shaping, and Treating of Steel, 8th ed., U.S. Steel, Pittsburgh, PA, 1964, pp. 355–56.Google Scholar
- 5.C.L. Briant and S.K. Banerji: “Intergranular Failure in Steel: The Role of Grain Boundary Composition,” Int. Met. Rev., 1978, 23(4), pp. 164–99.Google Scholar
- 7.Fractography and Atlas of Fractographs, vol. 9, Metals Handbook, 8th ed., American Society for Metals, Metals Park, OH, 1974, pp. 29–30.Google Scholar
- 8.J.C.M. Farrar and R.E. Dolby: “Lamellar Tearing in Welded Steel Fabrication, The Role of Sulfide Inclusions,” Sulfide Inclusions in Steels, J.J. de Barbadillo and E. Snape, ed., American Society for Metals, Metals Park, OH, 1975, pp. 252–68.Google Scholar
- 9.A.J. DeArdo and E.G. Hamburg: “Influence of Elongated Inclusions on the Mechanical Properties of High Strength Steel Plate,” Sulfide Inclusions in Steels, J.J. de Barbadillo and E. Snape, ed., American Society for Metals, Metals Park, OH, 1975, pp. 309–37.Google Scholar
- 10.Manual on Design and Application of Leaf Springs, SAE HS 788, Society of Automotive Engineers, Warrendale, PA, April 1980.Google Scholar
- 11.R.W. Hertzberg: Deformation and Fracture Mechanics of Engineering Materials, 3rd ed., John Wiley, New York, NY, 1983, p. 411.Google Scholar
- 12.Fatigue and Fracture, vol. 19, ASM Handbook, ASM International, Materials Park, OH, 1996, pp. 622, 625.Google Scholar