Effect of Specimen Geometry and Testing Method on Mixed Mode I-II Fracture Toughness of a Limestone Rock from Saudi Arabia

Evaluation of Mode I Fracture Toughness Assisted by the Numerical Determination of K-Resistance

“…Furthermore, differences may exist in the development of the process zone, as it is affected by the type of loading, e.g., bending versus tension. Khan and Al-Shayea (2000) found that the fracture toughness values of limestone measured using CSTBD and CCNBD specimens were, respectively, 0.42 and 0.61 MPam 0.5 . Chang et al (2002) reported that the fracture toughness values measured using chevronnotched SCB specimens for granite and marble were 1.39 and 1.11 MPam 0.5 , respectively.…”

“…These values are lower than the fracture toughness values measured using other specimens. Khan and Al-Shayea (2000) measured the fracture toughness of limestone using SCB, CSTBD, CCNBD, and SECRBB specimens; the average values measured using the SCB, CSTBD, CCNBD, and SECRBB specimens were 0.68, 0.42, 0.61, and 0.55 MPam 0.5 , respectively. Tutluoglu and Keles (2011) found that the fracture toughness values of andesite measured using CCNBD, SCB, and SNDB specimens were 1.45 ± 0.06 MPam 0.5 with five specimens, 0.94 ± 0.12 MPam 0.5 with 21 specimens, and 1.00 ± 0.09 MPam 0.5 with 20 specimens, respectively.…”

Mudcake effects on wellbore stress and fracture initiation pressure and implications for wellbore strengthening

“…Fortunately, numerous existing studies have shown that there is a strong relation between fracture toughness and tensile strength of rocks (Haberfield and Johnston 1989;Khan and Al-Shayea 2000;Whittaker et al 1992;Zhang et al 1998;Zhang 2002) and the later can be easily incorporated into the FIP solution (Eq. 41) in this paper by simply adding a tensile strength term to the numerator of Eq.…”

Experimental Investigation of Mixed Mode I/Ii Brittle Fracture That Uses Asymmetric-Semi Circular Bend Specimen

“…Many research works have been carried out using different test specimens and different techniques. The most popular brittle materials of interest for mixed mode fracture were mainly rocks [9], [10], [12], [14], [15], ceramics [5], [8], [20], [21], Glasses like plexiglass (PMMA) [2], [3], [7], [11], [15], [16], soda lime silica glass [4], [6], [7], [13], [17], [18], [19] and some polymers.…”

“…Indentation technique used are Knoop indentation tests [4], [6] and Vickers indentation tests [8], [13]. The popular test methods used for experiments include cracked Brazilian disc [10], [11], [12], [14], [19], [21] under diametrical compression and semicircular bend specimen [9], [12], [15], [16], [20] with thru crack under three point bending. From the literature it can be concluded that the simplicity of loading fixture, manufacturing ease and specimen pre-cracking were prime reasons for selecting specimens and testing procedure for particular mixed mode testing in brittle material [15].…”