Journal of Materials Science

, Volume 11, Issue 2, pp 363–375

The mechanism of brittle fracture in notched impact tests on polycarbonate

  • N. J. Mills
Papers

Abstract

The impact testing of notched polycarbonate bars that are thick enough to yield in plane strain has been investigated. Shear bands occur in the plastic zone that resemble the slip line field for yielding from a circular notch. Eventually, an internal craze nucleates at the tip of the plastic zone, where the stresses are highest, and a crack forms in the thickest part of the craze. Above −15‡ C the stress for the craze to nucleate is a nearly constant multiple of the yield stress. It is shown that previous observations that annealing polycarbonate causes a ductile to brittle transition is a consequence of testing bars of thickness less than 5 mm.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    W. E. Wolstenholme, S. E. Pregun andC. F. Stark,J. Appl. Polymer Sci. 8 (1964) 119.Google Scholar
  2. 2.
    T. L. Smith,J. Polymer Sci. C32 (1971) 269.Google Scholar
  3. 3.
    J. F. Knott, “Fundamentals of Fracture Mechanics” (Butterworths, London, 1973).Google Scholar
  4. 4.
    D. G. Legrand,J. Appl. Polymer Sci. 13 (1969) 2129.Google Scholar
  5. 5.
    A. M. Garde andV. Weiss,Met. Trans. 3 (1971) 2811.Google Scholar
  6. 6.
    R. Hill,Q. J. Mech. Appl. Maths. 2 (1949) 40.Google Scholar
  7. 7.
    D. Hull andT. W. Owen,J. Polymer Sci. Phys. 11 (1973) 2039.Google Scholar
  8. 8.
    E. Orowan,Rep. Progr. Phys. 12 (1948) 185.Google Scholar
  9. 9.
    G. Allen, D. C. W. Morley andT. Williams,J. Mater. Sci. 8 (1973) 1449.Google Scholar
  10. 10.
    C. Bauwens-Crowet, J. C. Bauwens andG. Homes,ibid 7 (1972) 176.Google Scholar
  11. 11.
    G. D. Wignall andG. W. Longman,ibid 8 (1973) 1439.Google Scholar
  12. 12.
    W. Lin andE. J. Kramer,J. Appl. Phys. 44 (1973) 4288.Google Scholar
  13. 13.
    L. Camwell andD. Hull,Phil. Mag. 27 (1973) 1135.Google Scholar
  14. 14.
    P. I. Vincent, in “Deformation and Fracture of High Polymers”, edited by H. H. Kansch, J. A. Hassell and R. I. Jaffee (Plenum Press, New York, 1973).Google Scholar
  15. 15.
    P. B. Bowden,Phil. Mag. 22 (1970) 455.Google Scholar
  16. 16.
    G. A. Adam, A. Cross andR. N. Haward,J. Mater. Sci. 10 (1975) 1582.Google Scholar
  17. 17.
    A. P. Green,Q. J. Mech. Appl. Maths. 6 (1953). 233.Google Scholar
  18. 18.
    J. R. Griffiths andD. R. J. Owen,J. Mech Phys. Solids 19 (1971) 419.Google Scholar
  19. 19.
    D. F. J. Ewing andJ. R. Griffiths,ibid 19 (1971) 389.Google Scholar
  20. 20.
    C. Bauwens-Crowet, J. M. Ots andJ. C. Bauwens,J. Mater. Sci. 9 (1974) 1197.Google Scholar
  21. 21.
    P. I. Donnelly andR. H. Ralston,Appl. Polymer. Symp. 1 (1965) 71.Google Scholar
  22. 22.
    R. P. Kambour,Polymer 5 (1964) 143.Google Scholar
  23. 23.
    Idem, J. Polymer Sci. A2 4 (1966) 359.Google Scholar
  24. 24.
    H. L. Brinson,Proc. Soc. Exp. Stress Anal. 28 (1971) 467.Google Scholar
  25. 25.
    P. L. Cornes andR. N. Haward,Polymer 15 (1974) 149.Google Scholar
  26. 26.
    N. J. Mills,Eng. Fract. Mech. 6 (1974) 537.Google Scholar
  27. 27.
    M. J. Miles andN. J. Mills,J. Polymer Sci. Letters 11 (1973) 563.Google Scholar
  28. 28.
    D. Hull,Acta Met. 8 (1960) 11.Google Scholar
  29. 29.
    F. Drabble, R. N. Haward andW. Johnson,Brit. J. Appl. Phys. 17 (1966) 241.Google Scholar
  30. 30.
    R. N. Haward andD. R. J. Owen,J. Mater. Sci. 8 (1973) 1136.Google Scholar
  31. 31.
    N. H. Macmillan andA. Kelly,Proc. Roy. Soc. A330 (1970) 291.Google Scholar
  32. 32.
    J. M. O'Reilly andW. R. Haaf,Rheol. Bull. 34 (1965) 6.Google Scholar

Copyright information

© Chapman and Hall Ltd. 1976

Authors and Affiliations

  • N. J. Mills
    • 1
  1. 1.Department of Physical Metallurgy and Science of MaterialsUniversity of BirminghamUK

Personalised recommendations