PREDICTION OF MODULUS CHANGES DURING FATIGUE IN HSLA (HIGH STRENGTH, LOW ALLOY) STEELS

Stiffness and vibration frequency of automotive structures are shown to be dependent on an effective modulus. The cyclic stress-strain curve is significantly different from the monotonic curve. As a result, the stiffness and vibration characteristics of a structural member subjected to cyclic loading cannot be related to the elastic modulus, but must be some function of the secant modulus as determined from the cyclic stress-strain curve. As cyclic loading proceeds, the secant modulus and, correspondingly, the stiffness and vibration characteristics decrease. The decrease in effective modulus of the AISI (American Iron and Steel Institute) 1005 is much greater for any specific stress or strain amplitude than for HI-FORM 50 and 80 steels. This implies that, rather than the performance degradation originally forecast by the automotive designer, improved performance could result from substituting HI-FORM steels for the current standard, AISI 1005 steel. This has important implications for the increased usage of light-gauge HSLA (high strength, low alloy) steels as an integral part of auto industry weight reduction programs.

  • Availability:
  • Supplemental Notes:
    • Presented at SAE Congress and Exposition, Detroit, 26 February-2 March 1979.
  • Corporate Authors:

    Society of Automotive Engineers (SAE)

    400 Commonwealth Drive
    Warrendale, PA  United States  15096
  • Authors:
    • Wilson, R B
  • Publication Date: 1979

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 00394081
  • Record Type: Publication
  • Source Agency: National Highway Traffic Safety Administration
  • Report/Paper Numbers: SAE 790004, HS-026 870U
  • Files: HSL, USDOT
  • Created Date: May 31 1985 12:00AM