Analysis of the diametrical compression test and the applicability to plastically deforming materials
Tóm tắt
The effect of contact flattening and material properties on the fracture stress calculation for the diametrical compression test used to evaluate compact strength was examined through finite element simulations. Two-dimensional simulations were carried out using linear elastic, elastoplastic, and porous elastoplastic models with commercial finite element software. A parametric study was performed by varying the elastic modulus (E), Poisson's ratio (ν), contact frictional coefficient (μ), yield stress (σyield), and compact relative density (RD). Stress contours generated from these simulations were compared to the Hertzian and Hondros analytical expressions. Linear elastic simulations show excellent agreement with the analytical solutions. Significant deviation, however, occurs for the elastoplastic and porous elastoplastic simulations at larger diametrical strain with material plasticity. A better understanding of the stress-state of diametrically loaded plastically deforming disks has been demonstrated in this computational and experimental work. Results from these finite element simulations confirm that the standard tensile strength calculation: σf = 2P/π Dt, is suitable for linear elastic materials. However, the incorporation of plasticity into the material model results in a significant change in the maximum principal stress field (magnitude and location) rendering the Hertzian estimate of tensile strength invalid. A map to check the validity of the Hertzian equation is proposed.
Tài liệu tham khảo
ASTM Designation E 8-01, “Standard Test Method for Tension Testing of Metallic Materials” (Philadelphia, 2001).
P. Stanley and J. M. Newton, J. Powder Bulk Sol.Technol. 1 (1977) 13.
P. Stanley, Int. J. Pharm. 227 (2001) 27.
L. J. Neergaard, D. A. Neergaard and M. S. Neergaard, J. Mater. Sci. 32 (1997) 2529.
A. BrÜckner-Foit, T. Fett, D. Munz and K. Schirmer, J. Euro. Ceram. Soc. 17 (1997) 689.
W. Weibull, J. Appl. Mech. 18 (1951) 293.
G. Hondros, Aust. J. Appl. Sci. 10 (1959) 243.
ASTM Designation D 3967-95a, “Standard Test Method for Splitting Tensile Strength of Intact Rock Core Specimens” (Philadelphia, 1996).
J. F. Labuz, S. Cattaneo and L. H. Chen, Const. Bldg. Mat. 15 (2001) 225.
G. Bernauer, U. SoltÉsz, and R. SchÄfer, Adv. Sci. Technol. 3B (1995) 1105.
R. H. Marion and J. K. Johnstone, Amer. Ceram. Soc. Bull. 56(11) (1977) 998.
D. K. Shetty, A. R. Rosenfield and W. H. Duckworth, J. Amer. Ceram. Soc. 69(6) (1986) 437.
G. Dewith, J. Mater. Sci. Let. 3 (1984) 1000.
O. Coube, PhD Thesis, U. Pierre et Marie Curie, Paris VI, 1999.
F. Bonollo, B. Molinas, I. Tangerini and A. Zambon, Mater. Sci. Tech. 10 (1994) 558.
L. Ehrnford, Acta Odontologica Scandinavica 39(1) (1981) 55.
L. Ehrnford, ibid. 39(2) (1981) 71.
E. P. Lautenschlager and J. K. Harcourt, J. Dental Research, 49(1) (1970) 175.
J. T. Fell and J. M. Newton, J. Pharm. Sci. 59(5) (1970) 688.
K. G. Pitt, J. M. Newton and P. Stanley, J. Mater. Sci. 23 (1988) 2723.
Idem., J. Phys. D: Appl. Phys. 22 (1989) 1114.
E. N. Hiestand AND C. B. Peot, Pharm. Tech. 63 (1974) 605.
H. G. Kristensen, P. Holm and T. Schaefer, Powder Technol. 44 (1985) 227.
T. L. Anderson, “Fracture Mechanics: Fundamentals and Applications,” (CRC Press, Boca Raton, FL, 1995).
C. Nystrom, W. Alex and K. Malmqvist, Acta Pharm. Suec. 14 (1977) 317.
K. Shinohara, C. E. Capes and A. E. Fouda, Powder Technol. 32 (1982) 163.
R. J. Roberts and R. C. Rowe, Int. J. Pharm. 37 (1987) 15.
G. Alderborn and C. NystrÖm, “Pharmaceutical Powder Compaction Technology” (Marcel Dekker, 1996).
H. Hertz, GesammelteWerke (CollectedWorks), Leipzig, 1895.
D. Maugis, “Contact, Adhesion and Rupture of Elastic Solids” (Springer Series in Solid-State Sciences, 2000) Vol. 130.
S. P. Timoshenko and J. N. Goodier, “Theory of Elasticity” (McGraw-Hill, New York, 1970).
M. K. Fahad, J. Mat. Sci. 31 (1996) 3723.
K. Shinohara and C. E. Capes, Powder Technol. 24 (1979) 179.
C. S. Desai and H. J. Sirinardane, “Constitutive Laws for Engineering Materials” (Prentice-Hall, Inc., Englewood Cliffs, NJ, 1984).
R. J. Roberts, R. C. Rowe and P. York, Int. J. Pharm. 105 (1994) 177.
G. E. Dieter, “Mechanical Metallurgy” (McGraw-Hill, London, UK, 1988).
S. Biwa and B. Storakers, J. Mech. Phys. Solids 43(8) (1995) 1303.
A. Castro-Montero, Z. Jia and S. P. Shah, ACI Mat. Journal 92/M29 (1995) 268.
C. A. Tang, X. H. Xu, S. Q. Kou, P. A. Lindqvist and H. Y. Liu, Int. J. Rock Mech. & Min. Sci. (In press).
Y. Hiramatsu and Y. Oka, ibid. 3 (1966) 89.