Abstract
The method to represent a general infinitesimal deformation as a deformation moment tensor is proposed and the physical meaning of deformation moment tensor in the case of microcracking is made clear. Developing the measuring and analysis system for acoustic emission waveform analysis, these moment tensor components due to microcracking can be determined experimentally. The remarkable method in this study is established to evaluate the moment tensor with the dynamic Green's function of finite media by computer simulation due to finite difference method and the iterative deconvolution with multiple Green's function.
Applying the present method to fracture toughness testing for ASTM A470 steel, moment tensor of quasicleavage facet within the plastic zone near the tip of the pre-crack was obtained from the six channels' acoustic waveform analysis. In addition to three-dimensional location of these microcracks, fracture mode and quantitative size of microcracks can be estimated from the obtained moment tensor.
Résumé
On propose une méthode de représentation d'une déformation générale infinitésimale sous forme d'une tenseur de moment de déformation et on clarifie la signification physique de ce tenseur dans le cas d'une microfissuration. Grâce à un développement d'un système de mesure et d'analyse de la forme d'onde en émission acoustique, on peut déterminer par voie expérimentale les composantes du tenseur de moment correspondant à une microfissuration. La méthode est remarquablement adaptée à l'évaluation du tenseur de moment associé à une fonction dynamique du Green pour les milieux finis, en utilisant une simulation par calcul, appliquée à la méthode des différences finies et à une decompositées par itération d'une fonction multiple de Green.
En appliquant la méthode aux essais de tenacité à la rupture de l'acier ASTM A470, on obtient à l'aide d'une analyse des ondes d'émissions acoustiques sur six canaux, le tenseur de moment relatif à une facette en quasiclivage dans la zone plastique au voisinage de l'extrémité d'une préfissure. En outre, le tenseur de moment permet d'estimer la localisation sur trois dimensions de ces microfissures, leur taille quantitative et le mode de rupture.
Article PDF
Similar content being viewed by others
Explore related subjects
Discover the latest articles, news and stories from top researchers in related subjects.Avoid common mistakes on your manuscript.
References
J.F. Knott, in Fundamentals of Fracture Mechanics, Butterworths, London (1973).
G.T. Hahn and A.R. Rosenfield, Metallurgical Transactions 6A (1975) 653–670.
S.P. Rawal and J. Gurland, Metallurgical Transactions 8A (1977) 691.
G. Green and J.F. Knott, Transactions of the ASME H 98 (1976) 37.
R.O. Ritchie, J.F. Knott and J.R. Rice, Journal of the Mechanics and Physics of Solids 21 (1973) 395–410.
A.G. Evans and R.M. Cannon, Acta Metallurgica 34 (1986) 761–800.
A.G. Evans and K.T. Faber, Journal of the American Ceramic Society 67 (1984) 255–260.
T. Kishi, S. Wakayama and S. Kohara, in Fracture Mechanics of Ceramics, Vol. 8, Plenum Press (1986) 85–100.
T. Mura, in Micromechanics of Defects in Solids, Martinus Nijhoff Publishers, The Hague (1982).
H.N.G. Wadley, C.B. Scruby and G. Shrimpton, Acta Metallurgica 29 (1981) 399–414.
T. Kishi and T. Ohira, Transactions of Japan Institute of Metals 24 (1983) 255–263.
C.B. Scruby, K.A. Stacey and G.R. Baldwin, Journal of Physics D 19 (1986) 1597–1612.
K.Y. Kim and W. Sachse, International Journal of Fracture 31 (1986) 211–231.
P. Fleischmann and P. Rouby, in Progress in Acoustic Emission II, The Japanese Society for Non-Destructive Inspection (1984) 114–124.
K. Aki and P.G. Richards, in Quantitative Seismology, Vol. I, W.H. Freeman and Company, San Francisco (1980).
M. Ohtsu and K. Ono, Journal of Acoustic Emission 3 (1984) 27–40.
T. Mura, Bulletin of the American Physical Society 6 (1961) 521.
R. Burridge and L. Knopoff, Bulletin of the Seismological Society of America, 54 (1964) 1875–1888.
C.B. Scruby and G.R. Baldwin, Journal of Acoustic Emission 3 (1984) 182–188.
A.N. Ceranoglu and Y.H. Pao, Journal of Applied Mechanics 48 (1981) 125–147.
Y. Fukunaga, M. Enoki and T. Kishi, to be published.
Z.S. Altermann and D. Lowenthal, Geophysical Journal of the Royal Astronomical Society 20 (1970) 101–126.
N.N. Hsu, J. Simmons and H.C. Hardy, Materials Evaluation 35 (1977) 100–106.
N. Ohisa and T. Kishi, in Proceedings of the 1982 Joint Conference on Experimental Mechanics, Society for Experimental Stress Analysis (1982) 359–364.
J.E. Michaels and Y.H. Pao, Journal of the Acoustical Society of America 77 (1985) 2005–2011.
J.D. Achenbach, K. Hirashima and K. Ohno, Journal of Sound and Vibration 89 (1983) 523–532.
J.W. Hutchinson, Acta Metallurgica 35 (1987) 1605–1619.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Enoki, M., Kishi, T. Theory and analysis of deformation moment tensor due to microcracking. Int J Fract 38, 295–310 (1988). https://doi.org/10.1007/BF00019805
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00019805