• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.3
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• pp.253-258
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• 2016

The effect of temperature on the fracture energy, crack propagation, and crack tip opening displacement (CTOD) was determined for particulate reinforced composites using the wedge splitting test. The materials that were used consisted of a polymer binder, an oxidizing agent, and aluminum particles. The test rate of the wedge splitting specimen was 50 mm/min, the temperature conditions were $50^{\circ}C$, room temperature, $-40^{\circ}C$, and $-60^{\circ}C$. The fracture energy, calculated from splitting load-crack mouth opening displacement(CMOD) curves, increased with decreasing temperature from $50^{\circ}C$ to $-40^{\circ}C$. In addition, the strength of the particulate reinforced composites increased sharply at $-60^{\circ}C$, and the composites evidenced brittle fracture due to the glass transition temperature. The strain fields near the crack tip were analyzed using digital image correlation.

• Tunnel and Underground Space
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• v.29 no.6
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• pp.523-531
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• 2019

In the applications of rock mechanics or rock engineering including drill and blast, drilling and mechanical excavation, the fracture toughness is an important factor. Several methods have been proposed to measure the fracture toughness of rocks. In this study, wedge splitting test specimen which is prepared with ease and tested under compression loading was used to obtain mode I fracture toughness of rocks. The equation of stress intensity factor through numerical analysis is proposed from the stress state of crack tip considering both vertical and horizontal loads due to the vertical load acting on the wedge. The validity of the wedge splitting test method was confirmed by comparing the mode I fracture toughness values obtained by the GD and SENB test specimens.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.7
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• pp.535-541
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• 2018

In this study, wedge splitting tests were performed to evaluate fracture behavior of particle reinforced composite materials. Crack resistance was evaluated by using CTOD (crack tip opening displacement) and crack tip opening angle (CTOA). The particle reinforced composites were tested under various temperature ($-60^{\circ}C{\sim}50^{\circ}C$) and load speed (5~500mm/min). Also, digital image correlation method (DIC) was used to analyze the strain field at crack tip. Test results showed that the fracture energy increased with decreasing temperature and crack resistance increased with increasing load velocity.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.12
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• pp.1021-1026
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• 2016

In this study, crack resistance is evaluated by the crack tip opening angle (CTOA) using a wedge splitting test (WST) on a viscoelastic particulate reinforced composite based on an HTPB binder. Generally, CTOA, as a function of crack extension, is used in order to determinate fracture resistance and has a steady state relative angle. Digital image correlation (DIC) is used to measure the crack tip opening displacement (CTOD) and crack extension for the critical crack tip opening angle (CTOAc). In these results, the CTOAc value of a particulate reinforced composite tends to approach a constant angle after a small amount of crack extension. The CTOAc value increases with decreasing temperature, from $50^{\circ}C$ to $-40^{\circ}C$. These CTOAc values may be used to measure fracture mechanics parameters for particulate reinforced composite.