Issue 75

R. Ince et alii, Fracture and Structural Integrity, 75 (20YY) 435-462; DOI: 10.3221/IGF-ESIS.75.30

Figure 9: a) SNDB specimen under hoop stress and stress distribution b) SNCB specimen under tensile stress c) Eqns. (23) and (24) of residual values according to a/d ratios

I MPLEMENTATION OF THE COMPLIANCE METHOD AND THE PEAK LOAD METHOD TO SNDB SPECIMEN TESTS BY T UTLUOGLU AND K ELES [14] xperimental studies on grained composites such as rock have revealed that their fracture properties are highly affected by the maximum grain size and the uniaxial compressive strength of the material (  c ). As a result, their behavior is characterized as being between brittle and ductile due to the internal structure of the material used. According to the TPM, the results of fracture test investigations performed on quasi-brittle materials have shown that there is a strong correlation between the uniaxial compressive strength and fracture toughness, while some properties related to the internal structure of the material, such as the maximum grain size, affect the CTOD c parameter. Experimental and numerical studies on SNCB specimens were initially performed using Ankara andesite by Alkilicgil [15] and Tutluoglu and Keles [14]. For Ankara andesite, the elasticity modulus ( E ), the splitting tensile strength ( f sp ), and Poisson’s ratio were reported as 12334 ± 135 MPa, 7.00 ± 0.67 MPa and 0.15, respectively, by Tutluoglu and Keles [14]. The SNCB testing on cylindrical specimens with a diameter ( D ) of approximately 100 mm and a height ( d ) of approximately 50 mm was conducted for span/diameter ratios s/D = 0.6 and 0.7, and four different relative initiation notch lengths,   = a 0 /d = 0.1, 0.2, 0.3 and 0.4. Both P -displacement and P-CMOD curves of the specimens were recorded in the fracture tests. The geometrical properties ( a 0 , D , r , d, and s ), the peak loads, and the critical CMOD values ( CMOD c ) at the peak load of successful test specimens are summarized in Tab. 2. In the specimen numbering in the first column of Tab. 2, the first E

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