Evaluation of the three-dimensional region around a crack tip by caustics

• Published in: International journal of fracture Vol. 98; no. 3-4; pp. 343 - 350
• Main Authors: RAFTOPOULOS, D. D, ZUGANG HUANG, KONSTA-GDOUTOS, M, GDOUTOS, E. E
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer 01-01-1999; Springer Nature B.V
• Subjects: Alkalies; Crack tips; Cracks; Exact sciences and technology; Fracture mechanics (crack, fatigue, damage...); Fundamental areas of phenomenology (including applications); Physics; Plane strain; Plane stress; Polymethyl methacrylate; Solid mechanics; Stress intensity factors; Structural and continuum mechanics; Thickness; Notched test piece; Fracture mechanics; Cracked plate; Biaxial stress; Methyl methacrylate polymer; Three dimensional space; Thickness; Experimental result; Caustic surface; Stress intensity factor; Stress distribution; Plane strain; Crack tip; Measurement method; Crack
• ISSN: 0376-9429; 1573-2673
• DOI: 10.1023/A:1018302504123

A study of the extent of the three-dimensional region around the border of a straight through-crack in mode-I loading was undertaken by the method of caustics. A series of experiments were performed in single edge-notched specimens made of PMMA (Plexiglas). It was found that the state of stress very close to the crack tip can be approximated as plane strain. Following this region, three-dimensional stress conditions hold in the neighborhood of the crack tip, up to a critical distance which depends on the thickness of the plate and the crack length. Beyond this critical distance plane stress conditions dominate. Results were obtained for the extent of the three-dimensional region as a function of the specimen thickness. The present investigation illuminates the complicated problem of the changing state of stress around cracks and establishes the limits of applicability of the method of caustics for the determination of stress intensity factors.