It is difficult to conduct cyclic tensile fatigue tests for fine ceramics because of its high brittleness, and a little eccentricity of loading axis and gripping device gives inaccurate strength data. So, a major part of cyclic fatigue tests have been carried out under bending load conditions, for the allowance of misalignment of loading axis is generous to some extent in the case of bending fa...

We study the fatigue fracture of disordered materials by means of computer simulations of a discrete element model. We extend a two-dimensional fracture model to capture the microscopic mechanisms relevant for fatigue and we simulate the diametric compression of a disc shape specimen under a constant external force. The model allows us to follow the development of the fracture process on the ma...

AIM To evaluate the cyclic fatigue fracture resistance of engine-driven F2 ProTaper instruments under reciprocating movement. METHODOLOGY A sample of 30 NiTi ProTaper F2 instruments was used. An artificial canal was made from a stainless steel tube, allowing the instruments to rotate freely. During mechanical testing, different movement kinematics and speeds were used, which resulted in three...

Recent studies have shown that nanotwinned copper (NT Cu) exhibits a combination of high strength and moderate ductility. However, most engineering and structural applications would also require materials to have superior fracture toughness and prolonged subcritical fatigue crack growth life. The current study investigates the effect of twin density on the crack initiation toughness and stable ...

The aim of this study was to investigate the effect of 50% hydrofluoric acid (HF) surface treatment on the cyclic fatigue resistance (CFR) of K3 NiTi instruments. Twenty as-received and twenty HF-treated K3 NiTi instruments were compared in CFR. The surface texture and fracture surface of two instrument groups were examined with a scanning electron microscope (SEM). Additionally, any change of ...

Articular stress fracture arising from the distal end of the third metacarpal bone (MC3) is a common serious injury in Thoroughbred racehorses. Currently, there is no method for predicting fracture risk clinically. We describe an ex-vivo biomechanical model in which we measured subchondral crack micromotion under compressive loading that modeled high speed running. Using this model, we determin...

Endovascular stents made of the superelastic nickel-titanium alloy Nitinol are subjected in service to tens of millions of loading cycles and even "single-event" overloads, both of which can potentially result in fracture and/or complete failure of the device. A fracture-mechanics-based methodology can provide a means to quantify relevant material parameters critical to the design against such ...

The aim of this study was to comparatively evaluate the bending resistance at 45º, the static and dynamic cyclic fatigue life, and the fracture type of the WaveOne (Dentsply Maillefer, Ballaigues, Switzerland) 25-08 and Reciproc (VDW, Munich, Germany) 25-08 instruments. A total of 60 nickel-titanium (NiTi) instruments (30 Reciproc and 30 WaveOne) from three different lots, each of which was 25 ...

INTRODUCTION C/C composites have been used for aerospace application due to their excellent properties such as low density, high heat resistance in inert gas atmosphere, high specific strength and etc. Since C/C composites have relatively higher fracture resistance than other CMCs, this material can also be used as structural components with high reliability. The fatigue properties are also imp...