Fracture toughness determination of brittle materials using small to extremely small specimens

✍ Scribed by G. Szendi-Horvath

• Publisher: Elsevier Science
• Year: 1980
• Tongue: English
• Weight: 570 KB
• Volume: 13
• Category: Article
• ISSN: 0013-7944
• DOI: 10.1016/0013-7944(80)90025-9

✦ Synopsis

Diametral compression of a grooved, disc shaped specimen is used to determine fracture toughness. This method's most important features are that extremely small specimens can be used and no knowledge of material properties is needed. It is suitable for many brittle materials, e.g. glass, cemented carbides, ceramics, many geological, mining and building materials, perspex-like plastics, etc. NOTATION D diameter of the circular element (m) $ torsional moment of inertia (m4) Klc critical stress intensity factor (MN/m3~) N depth of crack, groove or notch (m) P applied load (NJ Pi load for crack initiation in double torsion test (N) P, #b-a) fi P dS arithmetic mean of P (NJ P max max applied load in double torsion test (N) Pmin min applied load in double torsion test (N) p bearing pressure (N/m*) R radius of circular element (m) r radial distance of a point from the centre of the circular element (m) S projected width of the loaded section of the rim (m) T thickness of specimen (ml t width of crack surface (m) W width of specimen (m) W, moment arm (m) 8 deflection (m) oc compressive strength (N/m*) a, stress along the diame~r of the disc lo~~din~ to the loading (N~m*) oy tensile strength (N/m*) a, transverse principal stress in the centre of the disc (Nlm2f aY longitudinal principal stress in the centre of the disc (N/m*) o'sy stress along the diameter of the disc transverse to the loading (N/m*) Y Poisson's ratio 2a angle of load distribution (rad) Sign convention + denotes tensile effect -denotes compressive effect