Page 154 - T. Anderson-Fracture Mechanics - Fundamentals and Applns.-CRC (2005)

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134 Fracture Mechanics: Fundamentals and Applications

FIGURE 3.26 Comparison of the plastic deformation pattern in small-scale yielding (a) with slip patterns
under fully plastic conditions in three configurations. The estimated local stresses are based on the slip-line
analyses of McClintock, and apply only to nonhardening materials. Taken from McClintock, F.A., ‘‘Plasticity
Aspects of Fracture.’’ Fracture: An Advanced Treatise, Vol. 3, Academic Press, New York, 1971, pp. 47–225.

of fracture toughness are performed with bend-type specimens, such as the compact and three-
point bend geometries, because these specimens present the fewest experimental difficulties.
Figure 3.27 compares the cleavage-fracture toughness for bending and tensile loading. Although
the scatter bands overlap, the average toughness for the single-edge-notched bend specimens is
considerably lower than that of the center-cracked tension panels or the surface-cracked panels.
Crack depth and specimen size can also have an effect on fracture toughness, as Figure 3.28
illustrates. Note that the bend specimens with shallow cracks tend to have higher toughness than