Crack growth in a mixed-mode loading on marble beams under three point bending

Abstract

A combined theoretical and experimental study of a crack growth in a mixed-mode I-II loading is presented. A 160 x 40 x 20 mm marble beam, with an artificial crack 8 mm and 10 mm long each, was subjected to three point bending. The crack was located vertically to the beam's lower longitudinal fiber, through the whole width of the beam. The position of the crack was displaced from the center of the beam to one of the supporting points. The vertical force P, placed on the middle of the upper fiber of the beam, imposed the combination of the opening (mode I) and the sliding (mode II) modes on the crack mouth, creating the mixed-mode I-II loading case. The stress intensity factors K~ and KH, which describe the local stress and strain field around the crack tip, were determined by a suitable finite element program. The crack growth was defined by two classical fracture criteria of LEFM; the minimum strain energy density and the maximum circumferential stress criteria. The initial crack growth angle (0c) was calculated from both criteria and the critical load (Pc) from the minimum strain energy density (SED) criterion. These theoretical predictions were compared with some experimental results found from three marbles with different elastic constants; the Krystallina of Kavala, the Snow-white of Thassos and the White of Piges Drama. The theoretical results showed the same trend of 0c and Pc as the experimental ones and they are in good agreement.

Brittle Fracture Analysis Using a Ring-Shape Specimen Containing Two Angled Cracks

“…Also unlike some mixed mode fracture specimens such as the cracked beam specimen subjected to asymmetric three point bending (Xeidakis et al, 1996) which fails to provide pure mode II conditions, the ring specimen can be used for full mode I/II mixities. The compressive loading in the ring specimen is another benefit for testing quasi-brittle materials which are vulnerable to direct tensile loading.…”

A new fixture for fracture tests under mixed mode I/III loading

“…Numerous test specimens have been used by researchers for mixed mode I/II fracture experiments, see for example Ayatollahi, 2013, 2014;Ayatollahi and Aliha, 2009;Ayatollahi et al, 2011;Ayatollahi and Sedighiani, 2012;Erdogan and Sih, 1963;Ewing et al, 1976;Richard and Benitz, 1983;Shetty et al, 1987;Williams and Ewing, 1972;Xeidakis et al, 1996).…”

Evaluation of interfacial bond strength between Portland cement concrete and asphalt concrete layers using bi-material SCB test specimen

“…Erdogan & Sih (1963), Williams & Ewing (1972) and Theocaris (1984) used a rectangular plate containing an inclined center crack subjected to a uniform far field tension in their mixed mode fracture studies. The symmetric and asymmetrically loaded three or fourpoint bend specimens were also employed by researchers for investigating mode I and mixed mode brittle fracture (Fett et al, 1995;Xeidakis et al, 1996;Suresh et al, 1990, Aliha et al 2009Razavi et al, 2017Bahmani et al 2017;Heidari-Rarani et al, 2014), Disc type specimens including the centrally cracked Brazilian disk (BD) specimen, centrally cracked/notched ring specimen subjected to diametrall compression, edge notch disc bend (ENDB) and the semi-circular bend (SCB) specimen have been frequently employed for determining the mixed mode fracture resistance of various engineering materials such as rocks, graphite, concretes and polymers (Awaji & Sato, 1978;Ayatollahi et al, 2006;Ameri et al 2012Ameri et al ,2016Razmi & Mirsayar, 2017;Alhasan 2013;Fakhri et al 2017, Aliha et al 2008,2015a,c, 2017, Abd-Elhady 2013Al-Hdabi et al 2014;Dehghany et al 2017. However, some of these specimens have certain shortcomings.…”