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On crack-tip stress state: An experimental evaluation of three-dimensional effects

1986; Elsevier BV; Volume: 22; Issue: 2 Linguagem: Inglês

10.1016/0020-7683(86)90002-8

1879-2146

Ares J. Rosakis, K. Ravi‐Chandar,

Ultrasonics and Acoustic Wave Propagation

The extent of the region of three-dimensionality of the crack-tip stress field is investigated using reflected and transmitted caustics. The range of the applicability of two-dimensional near tip solutions is thus established experimentally. The experiments are performed using Plexiglass and high-strength 4340-steel compact tension specimens. A wide spectrum of thicknesses is investigated. At each thickness, measurements are performed at a variety of distances r from the crack tip, ranging from r/h = 0 to r/h = 2, where h is the specimen thickness. The results indicate that plane-stress conditions prevail at distances from the crack tip greater than half the specimen thickness, while no significant plane-strain region is detected. The experimental results are also compared to the crack-tip boundary-layer solution of Yang and Freund[1], and the numerical results of Levy, Marcal and Rice[2]. Their solutions are consistent with the results of this work and approach the plane stress field at r/h = 0.5. In addition, and unlike what might be commonly expected, the analytical solution[1] exhibits no plane-strain behavior very near the crack tip. This behavior is in good agreement with the results of both the transmission and the reflection experiments.