Determination of Stress Intensity Factor KIII for Three-Dimensional Crack by Using Caustic Method in Combination with Stress-Freezing and Stress-Releasing Technique

• Published in: Experimental mechanics Vol. 56; no. 3; pp. 463 - 474
• Main Authors: Wu, D. F., Shang, L., Pu, Y., Wang, H. T.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.03.2016
• Subjects: Biomedical Engineering and Bioengineering; Characterization and Evaluation of Materials; Control; Dynamical Systems; Engineering; Lasers; Optical Devices; Optics; Photonics; Solid Mechanics; Vibration; Stress intensity factor; Three-dimensional crack; Stress-releasing; Stress-freezing; Experimental stress analysis; Caustic method
• ISSN: 0014-4851; 1741-2765
• DOI: 10.1007/s11340-015-0113-2

In this paper, an experimental technique to determine the stress intensity factor K III for three-dimensional cracks using the method of reflected caustics in combination with the photoelastic stress-freezing and stress-releasing techniques is presented. The experimental model is a cylindrical bar with a three-dimensional surface crack under a load of pure torsion. To obtain the caustic pattern, a slice cut from the frozen model is annealed to release the frozen-stress. The results of this experimental method coincide favorably with the theoretical analysis results of Tweed and Rooke. Moreover, the mixed-mode stress intensity factors K II and K III of the three-dimensional crack are separately determined using the photoelastic and caustic methods. By using the present experimental technique, the mixed-mode stress intensity factors K II and K III for a three-dimensional crack are found to be easily separated.