Dynamic photoelastic investigation of two pressurized cracks approaching one another

• Published in: Engineering fracture mechanics Vol. 23; no. 1; pp. 237 - 249
• Main Authors: Simha, K.R.Y., Fourney, W.L., Barker, D.B., Dick, Richard D.
• Format: Journal Article
• Language: English
• Published: Tarrytown, NY Elsevier Ltd 1986; Oxford Elsevier
• Subjects: cameras; crack propagation; Exact sciences and technology; Fundamental areas of phenomenology (including applications); materials testing; Measurement and testing methods; notch testing; photoelasticity; Physics; Solid mechanics; Structural and continuum mechanics; Photoelasticity; Crack; Crack propagation
• ISSN: 0013-7944; 1873-7315
• DOI: 10.1016/0013-7944(86)90190-6

This paper presents results from a dynamic photoelastic investigation of explosively driven cracks approaching one another. A Cranz-Schardin (spark-gap) camera was utilized to observe the interaction and record the isochromatic fringe patterns in 50.8 mm (2 in.) thick plexiglas models as the two cracks approached one another. Small charges of PETN were detonated to simultaneously initiate and drive the cracks from two boreholes notched to assure proper propagation of the cracks being observed. The speed of the two intersecting cracks were on the order of 30% of the shear-wave speed in the model material. Experimental results are presented for four separate angles of interaction: 180° (head-on interaction), 120°, 90° and 60°. An approximate analytical model is also presented to explain the observed behavior of two cracks intersecting head on.