Evaluation of size effect on mixed-mode fracture behavior of epoxy/silica nanocomposites

The aim of this study was to examine the effect of size on the mixed-mode fracture toughness of quasi-brittle nanocomposites with the help of modified maximum tangential stress criterion. The literature reveals that the effect of size on mixed-mode fracture behavior of brittle nanocomposites has not been well investigated previously using modified maximum tangential stress criterion. The studied nanocomposites were made of epoxy resin reinforced with 7 wt%, 20–30 nm nanosilica. The accuracy of the method was assessed by taking into account the high-order terms of Williams series expansion along with finite element over-deterministic method. To investigate the effect of size on fracture toughness, a number of three-point semi-circular bending tests with different radii and four angles of edge–crack orientation were conducted and subjected to mixed-mode loading. The size of fracture process zone and apparent fracture toughness ( Kc) were also evaluated as a function of sample size. Experimental results showed that the proposed approach can accurately predict the fracture behavior of studied nanocomposites.

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A modified maximum tangential stress criterion for determination of the fracture toughness in bi-material notches – Part 1: Theory

Engineering Solid Mechanics ◽

10.5267/j.esm.2014.8.002 ◽

2014 ◽

Vol 2 (4) ◽

pp. 277-282 ◽

Cited By ~ 5

Author(s):

M. M. Mirsayar

Keyword(s):

Fracture Toughness ◽

Tangential Stress ◽

Maximum Tangential Stress ◽

Stress Criterion ◽

Maximum Tangential Stress Criterion

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Modified maximum tangential stress criterion for fracture behavior of zirconia/veneer interfaces

Journal of the Mechanical Behavior of Biomedical Materials ◽

10.1016/j.jmbbm.2015.11.037 ◽

2016 ◽

Vol 59 ◽

pp. 236-240 ◽

Cited By ~ 25

Author(s):

M.M. Mirsayar ◽

P. Park

Keyword(s):

Tangential Stress ◽

Fracture Behavior ◽

Maximum Tangential Stress ◽

Stress Criterion ◽

Maximum Tangential Stress Criterion

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Biaxial Fracture Behavior of Polycrystalline Alumina

Materials Science Forum ◽

10.4028/www.scientific.net/msf.475-479.1329 ◽

2005 ◽

Vol 475-479 ◽

pp. 1329-1332

Author(s):

Masayuki Tsukada ◽

Eiichi Sato ◽

Kazuhiko Kuribayashi

Keyword(s):

Fracture Toughness ◽

Mixed Mode ◽

Fracture Behavior ◽

Mixed Mode Fracture ◽

Polycrystalline Alumina ◽

Mode Fracture ◽

Multiaxial Stress State ◽

Four Point Bending ◽

Biaxial Tests ◽

Fracture Tests

Fracture behavior under multiaxial stress state of polycrystalline alumina was studied from the view point of an artificial crack propagation and fracture from a natural flaw. The former was studied by mixed-mode fracture toughness tests; asymmetric four-point bending and diametral compression techniques were carried out using precracked and notched specimens. The latter was studied by biaxial fracture tests in compression and torsion loading; multiaxial fracture statistics was applied to the measured fracture envelope. The ratio KIIC/KIC obtained from the biaxial tests was higher than that obtained by the mixed-mode fracture toughness tests. It revealed that the fracture from an artificial flaw does not simulate the fracture from a naturall flaw in polycrystalline ceramics.

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Study of mixed mode fracture toughness and fracture trajectories in gypsum interlayers in corrosive environment

Royal Society Open Science ◽

10.1098/rsos.171374 ◽

2018 ◽

Vol 5 (1) ◽

pp. 171374 ◽

Cited By ~ 5

Author(s):

Bao Xiankai ◽

Tao Meng ◽

Zhao Jinchang

Keyword(s):

Fracture Toughness ◽

Mixed Mode ◽

Process Zone ◽

Fracture Load ◽

Mixed Mode Fracture ◽

Mode Fracture ◽

Damage Degree ◽

Experimental Fracture ◽

Inclination Angles ◽

Hydrocarbon Storage

Based on the engineering background of water dissolving mining for hydrocarbon storage in multi-laminated salt stratum, the mixed mode fracture toughness and fracture trajectory of gypsum interlayers soaked in half-saturated brine at various temperatures (20°C, 50°C and 80°C) were studied by using CSNBD (centrally straight-notched Brazilian disc) specimens with required inclination angles (0°, 7°, 15°, 22°, 30°, 45°, 60°, 75°, 90°) and SEM (scanning electron microscopy). The results showed: (i) The fracture load of gypsum specimens first decreased then increased with increasing inclination angle, due to the effect of friction coefficient. When soaked in brine, the fracture toughness of gypsum specimens gradually decreased with increasing brine temperature. (ii) When soaked in brine, the crystal boundaries of gypsum separated and became clearer, and the boundaries became more open between the crystals with increasing brine temperature. Besides, tensile micro-cracks appeared on the gypsum crystals when soaked in 50°C brine, and the intensity of tensile cracks became more severe when soaking in 80°C brine. (iii) The experimental fracture envelopes derived from the conventional fracture criteria and lay outside these conventional criteria. The experimental fracture envelopes were dependent on the brine temperature and gradually expanded outward as brine temperature increases. (iv) The size of FPZ (fracture process zone) was greatly dependent on the damage degree of materials and gradually increased with increase of brine temperature. The study has important implication for the control of shape and size of salt cavern.

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