A Simple Determination of Von Karman Critical Velocities

  • R. B. PondSr.
  • J. M. WinterJr.

Abstract

The ductility of non-brittle engineering metals and alloys has been shown by Hoppmann to be a function of deformation velocity. The ductility increases to some maximum at the Karman Critical Velocity and thereafter diminishes. This implies that the volume of the plastic zone at the tip of the crack will vary as a function of deformation velocity, and that at the Karman velocity the character of the material drastically changes toward a brittle material. An analysis of this phenomena is presented. A tensile test is generally required to determine the critical value. This technique is simplified by using the non-destructive characterization of the scleroscope hardness which is shown to rank the critical velocities in a reproducible manner. The reasons for this relationship are analyzed by using the Pond — Glass method of critical velocity determination.

Keywords

Brittle Shrinkage Ductility Cold Work 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    Th. v. Karman “On The Propagation of Plastic Strains In Solids, “Nat. Defense Research Council Rept. No. A-29 (OSRD No. 365) (1942).Google Scholar
  2. 2.
    G. I. Taylor, 6th International Congress of Applied Mechanics, Paris, (1946).Google Scholar
  3. 3.
    D. S. Clark “The Behavior of Metals under Dynamic Loading”, Trans. ASM, 46:34, (1954).Google Scholar
  4. 4.
    P. E. Duwez & D. S. Clark, “An Experimental Study of the Propagation of Plastic Deformation Under Conditions of Longitudinal Impact”, Proc. ASTM, 46, (1954).Google Scholar
  5. 5.
    W. H. Hoppmann, Proc. ASTM, 47:533, (1947).Google Scholar
  6. 6.
    R. B. Pond, “Cold Extrude Rapidly to Produce Long, Thin-wall Aluminum Tubes”, Met. Progress 6:89, (1966).Google Scholar
  7. 7.
    R. B. Pond & C. M. Glass, “Crystallographic Aspects of High Velocity Deformation of Al-Single Crystals,” Response of Metals to High Velocity Deformation, Interscience Publishers, Inc., New York, (1961).Google Scholar
  8. 8.
    R. B. Pond & C. M. Glass, “Metallurgical Observations and Energy Partitioning” High Velocity Impact Phenomena, Academic Press (1970).Google Scholar

Copyright information

© Plenum Press, New York 1980

Authors and Affiliations

  • R. B. PondSr.
    • 1
    • 2
  • J. M. WinterJr.
    • 2
  1. 1.The Johns Hopkins UniversityBaltimoreUSA
  2. 2.Marvalaud, Inc.WestminsterUSA

Personalised recommendations